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Soap / Janhavi S. Raut in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6347–6353 Titre : Soap : the polymorphic genie of hierarchically structured soft condensed-matter products Type de document : texte imprimé Auteurs : Janhavi S. Raut, Auteur ; Vijay M. Naik, Auteur Année de publication : 2008 Article en page(s) : p. 6347–6353 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Metal salts Fatty acids Soaps Résumé : More than 5 million tonnes of metal salts of fatty acids are manufactured and used worldwide every year, to create a range of soft condensed-matter products such as bar soaps, stick deodorants, personal care creams, toothpastes, and lubricant greases. These molecules, popularly known as soaps, are capable of forming a plethora of states and self-assembled aggregates such as micelles, liquid crystals, solid crystals, and gels, whose characteristic sizes or domain sizes can span from nanometers to centimeters. The type and mix of the phases formed, their morphologies, and their states of dispersion or the nature of their further supra-assemblies dictate the underlying micromechanical structures of products, which, in turn, are responsible for their optical, structural, and rheological properties. Developing processing guidelines to manipulate characteristic micromechanical structures is therefore key to obtaining the desired look, touch, feel, and function of these products. The article discusses a few illustrative examples of these structure−property relationships demonstrated by multiscale soap assemblies. Observations of some novel tertiary structures formed by crystallizing soap fibers at the air−water interface, serendipitously discovered by us in the recent past, are also discussed, to illustrate the richness and mysteries of the well-studied and so-called mature subject of soaps. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714753 [article] Soap : the polymorphic genie of hierarchically structured soft condensed-matter products [texte imprimé] / Janhavi S. Raut, Auteur ; Vijay M. Naik, Auteur . - 2008 . - p. 6347–6353. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6347–6353 Mots-clés : Metal salts Fatty acids Soaps Résumé : More than 5 million tonnes of metal salts of fatty acids are manufactured and used worldwide every year, to create a range of soft condensed-matter products such as bar soaps, stick deodorants, personal care creams, toothpastes, and lubricant greases. These molecules, popularly known as soaps, are capable of forming a plethora of states and self-assembled aggregates such as micelles, liquid crystals, solid crystals, and gels, whose characteristic sizes or domain sizes can span from nanometers to centimeters. The type and mix of the phases formed, their morphologies, and their states of dispersion or the nature of their further supra-assemblies dictate the underlying micromechanical structures of products, which, in turn, are responsible for their optical, structural, and rheological properties. Developing processing guidelines to manipulate characteristic micromechanical structures is therefore key to obtaining the desired look, touch, feel, and function of these products. The article discusses a few illustrative examples of these structure−property relationships demonstrated by multiscale soap assemblies. Observations of some novel tertiary structures formed by crystallizing soap fibers at the air−water interface, serendipitously discovered by us in the recent past, are also discussed, to illustrate the richness and mysteries of the well-studied and so-called mature subject of soaps. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714753

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Biomimic superhydrophobic surface with high adhesive forces / Jinming Xi in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6354–6357 Titre : Biomimic superhydrophobic surface with high adhesive forces Type de document : texte imprimé Auteurs : Jinming Xi, Auteur ; Lei Jiang, Auteur Année de publication : 2008 Article en page(s) : p. 6354–6357 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polydimethylsiloxane surfaces Water contact angle Rose petal--microstructures Adhesive forces Résumé : Superhydrophobic polydimethylsiloxane (PDMS) surfaces that contain microbinary and nanobinary structures with a water contact angle (CA) of >150° are created by duplicating the microstructures of a rose petal. The resulting surface has the same microstructures and high adhesive property as a rose petal; the water CA of the surface is as high as 154.3°. Interestingly, this surface can hold water droplets through the use of very strong adhesive forces, and the maximum adhesive force is ~63.8 μN. Furthermore, the resulting surface has another important property; it shows superhydrophobic property in a wide range of pH values from 1.07 to 13.76. Therefore, it is believed that the as-prepared surface can be used in the fabrication of chemical engineering materials, microfluidic devices, and the transportation of a small amount of corrosive liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071603n [article] Biomimic superhydrophobic surface with high adhesive forces [texte imprimé] / Jinming Xi, Auteur ; Lei Jiang, Auteur . - 2008 . - p. 6354–6357. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6354–6357 Mots-clés : Polydimethylsiloxane surfaces Water contact angle Rose petal--microstructures Adhesive forces Résumé : Superhydrophobic polydimethylsiloxane (PDMS) surfaces that contain microbinary and nanobinary structures with a water contact angle (CA) of >150° are created by duplicating the microstructures of a rose petal. The resulting surface has the same microstructures and high adhesive property as a rose petal; the water CA of the surface is as high as 154.3°. Interestingly, this surface can hold water droplets through the use of very strong adhesive forces, and the maximum adhesive force is ~63.8 μN. Furthermore, the resulting surface has another important property; it shows superhydrophobic property in a wide range of pH values from 1.07 to 13.76. Therefore, it is believed that the as-prepared surface can be used in the fabrication of chemical engineering materials, microfluidic devices, and the transportation of a small amount of corrosive liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071603n

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Preparation of functional nanoparticles by assembling block copolymers formed by living radical polymerization / Tomomi Sato in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6358–6361 Titre : Preparation of functional nanoparticles by assembling block copolymers formed by living radical polymerization Type de document : texte imprimé Auteurs : Tomomi Sato, Auteur ; Sakiko Tsuji, Auteur ; Haruma Kawagauchi, Auteur Année de publication : 2008 Article en page(s) : p. 6358–6361 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : PGLM core/PNIPAM Block copolymers Magnetite nanoparticles Résumé : A series of poly(glycerol methacrylate) (PGLM)-block-poly(N-isopropylacrylamide) (PNIPAM)s were prepared by quasi-living radical polymerization using a photosensitive iniferter. PGLM core/PNIPAM shell particles were prepared by self-assembling of the block copolymers in a methanol−tetrahydrofuran solution followed by cross-linking of the core. Magnetite nanoparticles were prepared in situ using penetrated ferric and ferrous ions in the core. The composite particles were stably dispersed in water at room temperature but easily collected by a magnet at the temperature above the lower critical solution temperature of PNIPAM. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017614 [article] Preparation of functional nanoparticles by assembling block copolymers formed by living radical polymerization [texte imprimé] / Tomomi Sato, Auteur ; Sakiko Tsuji, Auteur ; Haruma Kawagauchi, Auteur . - 2008 . - p. 6358–6361. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6358–6361 Mots-clés : PGLM core/PNIPAM Block copolymers Magnetite nanoparticles Résumé : A series of poly(glycerol methacrylate) (PGLM)-block-poly(N-isopropylacrylamide) (PNIPAM)s were prepared by quasi-living radical polymerization using a photosensitive iniferter. PGLM core/PNIPAM shell particles were prepared by self-assembling of the block copolymers in a methanol−tetrahydrofuran solution followed by cross-linking of the core. Magnetite nanoparticles were prepared in situ using penetrated ferric and ferrous ions in the core. The composite particles were stably dispersed in water at room temperature but easily collected by a magnet at the temperature above the lower critical solution temperature of PNIPAM. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017614

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Designing multiscale structures for desired properties of ice cream / James F. Crilly in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6362–6367 Titre : Designing multiscale structures for desired properties of ice cream Type de document : texte imprimé Auteurs : James F. Crilly, Auteur ; Andrew B. Russell, Auteur ; Andrew R. Cox, Auteur Année de publication : 2008 Article en page(s) : p. 6362–6367 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ice cream Length-scales Résumé : Ice cream is a complex multiphase structure consisting of ice, air, and fat as dispersed phases at a range of different length-scales, all embedded in a continuous phase consisting of unfrozen sugar solution known as the matrix or serum. The entire structure is the result of both the ingredients and all the processes used in ice cream manufacture including emulsification, freezing, and aeration. It is thermodynamically unstable and delivered quality can only be assured at low and stable temperatures. Physicochemical processes during storage can lead to loss of quality by coarsening of the ice particles, disproportionation of the air, and the loss of water from the matrix. Product design for specific sensory, stability, shape, and increasingly, nutritional properties, is a challenging task and must take account of all these aspects of the structure. Almost all properties are sensitive to the size, density, and morphology of the dispersed phases as droplets, cells, crystals, or even micelles. Finer structures, in general, result in more desirable organoleptic properties such as creaminess and smoothness but the interfacial dynamics are more rapid, leading to less stability. Even small changes in the relative densities of the dispersed phases such as in the case of low-fat or fat-free products can dramatically change key properties such as taste perception, mouth-feel, and rate of melt. Conventional formulation and processing techniques complemented by the use of specific additives such as emulsifiers and stabilizers enable some control, albeit limited, over the interfacial dynamics and stability. New ingredients and new technologies (such as low temperature extrusion) have been developed to enable higher levels of control on the interfacial behavior either through direct molecular intervention on an interface or new structuring processes wherein interfaces are created in a new or different way. Examples of new ways of influencing the ice, fat, and air interfaces will be discussed such as “ice structuring protein” and hydrophobins. Challenges that remain highlight the need for new types of molecular and microstructural interventions to achieve the next levels in design capability for the ice creams of tomorrow. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701773z [article] Designing multiscale structures for desired properties of ice cream [texte imprimé] / James F. Crilly, Auteur ; Andrew B. Russell, Auteur ; Andrew R. Cox, Auteur . - 2008 . - p. 6362–6367. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6362–6367 Mots-clés : Ice cream Length-scales Résumé : Ice cream is a complex multiphase structure consisting of ice, air, and fat as dispersed phases at a range of different length-scales, all embedded in a continuous phase consisting of unfrozen sugar solution known as the matrix or serum. The entire structure is the result of both the ingredients and all the processes used in ice cream manufacture including emulsification, freezing, and aeration. It is thermodynamically unstable and delivered quality can only be assured at low and stable temperatures. Physicochemical processes during storage can lead to loss of quality by coarsening of the ice particles, disproportionation of the air, and the loss of water from the matrix. Product design for specific sensory, stability, shape, and increasingly, nutritional properties, is a challenging task and must take account of all these aspects of the structure. Almost all properties are sensitive to the size, density, and morphology of the dispersed phases as droplets, cells, crystals, or even micelles. Finer structures, in general, result in more desirable organoleptic properties such as creaminess and smoothness but the interfacial dynamics are more rapid, leading to less stability. Even small changes in the relative densities of the dispersed phases such as in the case of low-fat or fat-free products can dramatically change key properties such as taste perception, mouth-feel, and rate of melt. Conventional formulation and processing techniques complemented by the use of specific additives such as emulsifiers and stabilizers enable some control, albeit limited, over the interfacial dynamics and stability. New ingredients and new technologies (such as low temperature extrusion) have been developed to enable higher levels of control on the interfacial behavior either through direct molecular intervention on an interface or new structuring processes wherein interfaces are created in a new or different way. Examples of new ways of influencing the ice, fat, and air interfaces will be discussed such as “ice structuring protein” and hydrophobins. Challenges that remain highlight the need for new types of molecular and microstructural interventions to achieve the next levels in design capability for the ice creams of tomorrow. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701773z

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Microphase separation and morphology of the real polymer system by dynamic density functional theory, based on the equation of state / Hui Xu in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6368–6373 Titre : Microphase separation and morphology of the real polymer system by dynamic density functional theory, based on the equation of state Type de document : texte imprimé Auteurs : Hui Xu, Auteur ; Tengfang Wang, Auteur ; Yongmin Huang, Auteur Année de publication : 2008 Article en page(s) : p. 6368–6373 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polystyrene blends Polybutadiene EOS-based DDFT Résumé : Microphase separation and morphology evolution of polystyrene and polybutadiene blends are quantitatively studied by the dynamic density functional theory that is based on the equation of state (EOS-based DDFT). The structure parameters of coarse-grained beads are regressed from the experimental pressure−volume−temperature data of pure components. The comparisons between simulated and experimental results are presented as illustrations. Notably, in the region near the critical composition, the deviation of the order−disorder transition temperature between simulation and experiment is En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701776r [article] Microphase separation and morphology of the real polymer system by dynamic density functional theory, based on the equation of state [texte imprimé] / Hui Xu, Auteur ; Tengfang Wang, Auteur ; Yongmin Huang, Auteur . - 2008 . - p. 6368–6373. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6368–6373 Mots-clés : Polystyrene blends Polybutadiene EOS-based DDFT Résumé : Microphase separation and morphology evolution of polystyrene and polybutadiene blends are quantitatively studied by the dynamic density functional theory that is based on the equation of state (EOS-based DDFT). The structure parameters of coarse-grained beads are regressed from the experimental pressure−volume−temperature data of pure components. The comparisons between simulated and experimental results are presented as illustrations. Notably, in the region near the critical composition, the deviation of the order−disorder transition temperature between simulation and experiment is En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701776r

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Stress engineered polymeric nanostructures by self-organized splitting of microstructures / Danish Faruqui in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6374–6378 Titre : Stress engineered polymeric nanostructures by self-organized splitting of microstructures Type de document : texte imprimé Auteurs : Danish Faruqui, Auteur ; Ashutosh Sharma, Auteur Année de publication : 2008 Article en page(s) : p. 6374–6378 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Microstructures Polymeric nanostructures Flexibility Résumé : We propose a generic, simple, and parallel nanofabrication technique to obtain three-dimensional multiscale nanostructures based on stress-induced cracking of thin film polymeric microstructures at their sharp edges. The technique was applied to obtain an array of nanochannels on large areas (∼squared centimeters) with channel widths and heights of ∼100 nm. The technique offers flexibility in nanofabrication by providing very simple controls on the feature size, aspect ratio, and the complexity of the nanostructures thus obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017838 [article] Stress engineered polymeric nanostructures by self-organized splitting of microstructures [texte imprimé] / Danish Faruqui, Auteur ; Ashutosh Sharma, Auteur . - 2008 . - p. 6374–6378. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6374–6378 Mots-clés : Microstructures Polymeric nanostructures Flexibility Résumé : We propose a generic, simple, and parallel nanofabrication technique to obtain three-dimensional multiscale nanostructures based on stress-induced cracking of thin film polymeric microstructures at their sharp edges. The technique was applied to obtain an array of nanochannels on large areas (∼squared centimeters) with channel widths and heights of ∼100 nm. The technique offers flexibility in nanofabrication by providing very simple controls on the feature size, aspect ratio, and the complexity of the nanostructures thus obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017838

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Lipase immobilization on oleic acid-pluronic (L-64) block copolymer coated magnetic nanoparticles, for hydrolysis at the oil/water interface / Iram Mahmood in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6379–6385 Titre : Lipase immobilization on oleic acid-pluronic (L-64) block copolymer coated magnetic nanoparticles, for hydrolysis at the oil/water interface Type de document : texte imprimé Auteurs : Iram Mahmood, Auteur ; Chen, Guo, Auteur ; Hansong Xia, Auteur Année de publication : 2008 Article en page(s) : p. 6379–6385 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Iron oxide nanoparticles Oleic acid Pluronic Transmission electron microscopy X-ray diffraction Résumé : Here, we have reported a new approach for utilizing oleic acid−Pluronic L-64 block copolymer coated iron oxide nanoparticles as supports for enzyme immobilization. Iron oxide nanoparticles were prepared by a coprecipitation method and were coated with oleic acid and Pluronic to achieve higher stability and dispersibility. The surface morphology and size of the particle, as determined by transmission electron microscopy (TEM), was ±10 nm. X-ray diffraction (XRD) patterns were taken over a range from 10° to 90° 2θ, using Cu Kα radiation. Saturation magnetization values, measured at 300 K, varied from 34.6 emu/g to 60.8 emu/g. The possible interaction behavior of oleic acid and Pluronic was observed by Fourier transform infrared (FTIR) analysis and nuclear magnetic resonance (NMR) studies. Further potential of this material as a support for lipase immobilization and enzymatic hydrolysis at the oil/water interface was also investigated. The features of the surface-coated magnetic particles enable the adsorption of lipase from Candida cylindraces via strong hydrophobic interactions, which enhances the stability of the adsorbed enzyme molecules. The stability of the catalyst and, hence, its industrial applicability was tested by performing subsequent reaction cycles for the hydrolysis of olive oil. The activity of the immobilized lipase, pretreated with its substrate, was 510 U/g-matrix and was observed to be maintained at levels as high as 90% of its original activity for up to at least seven reuses. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701788x [article] Lipase immobilization on oleic acid-pluronic (L-64) block copolymer coated magnetic nanoparticles, for hydrolysis at the oil/water interface [texte imprimé] / Iram Mahmood, Auteur ; Chen, Guo, Auteur ; Hansong Xia, Auteur . - 2008 . - p. 6379–6385. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6379–6385 Mots-clés : Iron oxide nanoparticles Oleic acid Pluronic Transmission electron microscopy X-ray diffraction Résumé : Here, we have reported a new approach for utilizing oleic acid−Pluronic L-64 block copolymer coated iron oxide nanoparticles as supports for enzyme immobilization. Iron oxide nanoparticles were prepared by a coprecipitation method and were coated with oleic acid and Pluronic to achieve higher stability and dispersibility. The surface morphology and size of the particle, as determined by transmission electron microscopy (TEM), was ±10 nm. X-ray diffraction (XRD) patterns were taken over a range from 10° to 90° 2θ, using Cu Kα radiation. Saturation magnetization values, measured at 300 K, varied from 34.6 emu/g to 60.8 emu/g. The possible interaction behavior of oleic acid and Pluronic was observed by Fourier transform infrared (FTIR) analysis and nuclear magnetic resonance (NMR) studies. Further potential of this material as a support for lipase immobilization and enzymatic hydrolysis at the oil/water interface was also investigated. The features of the surface-coated magnetic particles enable the adsorption of lipase from Candida cylindraces via strong hydrophobic interactions, which enhances the stability of the adsorbed enzyme molecules. The stability of the catalyst and, hence, its industrial applicability was tested by performing subsequent reaction cycles for the hydrolysis of olive oil. The activity of the immobilized lipase, pretreated with its substrate, was 510 U/g-matrix and was observed to be maintained at levels as high as 90% of its original activity for up to at least seven reuses. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701788x

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Preparation of uniformly sized agarose microcapsules by Membrane emulsification for application in sorting bacteria / Qing-Zhu Zhou in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6386–6390 Titre : Preparation of uniformly sized agarose microcapsules by Membrane emulsification for application in sorting bacteria Type de document : texte imprimé Auteurs : Qing-Zhu Zhou, Auteur ; Xing-Yu Liu, Auteur ; Shuang-Jiang Liu, Auteur Année de publication : 2008 Article en page(s) : p. 6386–6390 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Bacterial cells Membrane emulsification method Aqueous solution Résumé : In an attempt to develop a high-throughput culture process, bacterial cells were encapsulated in uniform-sized agarose microcapsules prepared by membrane emulsification method. A mixture of diluted bacterial cell suspensions and agarose aqueous solution (40 °C) was used as the water phase, and a mixture of liquid paraffin and petroleum ether that contained hexaglycerin penta ester (PO-500) was used as the oil phase. The water phase permeated through uniform membrane pores into the oil phase under the pressure of nitrogen gas to form a uniform water/oil (W/O) emulsion; the emulsion then was cooled to form uniformly sized gel capsules. The size of microcapsules can be controlled by membranes with different pore sizes, because the mean diameters of the capsules were proportional to the mean pore diameters of the membranes. These microcapsules, which contained bacterial cells, were transferred into a column vessel and were incubated for 14 days to form microcolonies within the microcapsules. The cultured microcapsules were analyzed by flow cytometry, and the microbial colonized capsules were separated from free-living cells and empty capsules, based on the distinctive light-scattering signature of the microcapsules. The result showed that membrane emulsification preserved the viability of cells and this method was effective to create niches for various bacterial cells growing in high-throughput cultivation vessels. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800011r [article] Preparation of uniformly sized agarose microcapsules by Membrane emulsification for application in sorting bacteria [texte imprimé] / Qing-Zhu Zhou, Auteur ; Xing-Yu Liu, Auteur ; Shuang-Jiang Liu, Auteur . - 2008 . - p. 6386–6390. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6386–6390 Mots-clés : Bacterial cells Membrane emulsification method Aqueous solution Résumé : In an attempt to develop a high-throughput culture process, bacterial cells were encapsulated in uniform-sized agarose microcapsules prepared by membrane emulsification method. A mixture of diluted bacterial cell suspensions and agarose aqueous solution (40 °C) was used as the water phase, and a mixture of liquid paraffin and petroleum ether that contained hexaglycerin penta ester (PO-500) was used as the oil phase. The water phase permeated through uniform membrane pores into the oil phase under the pressure of nitrogen gas to form a uniform water/oil (W/O) emulsion; the emulsion then was cooled to form uniformly sized gel capsules. The size of microcapsules can be controlled by membranes with different pore sizes, because the mean diameters of the capsules were proportional to the mean pore diameters of the membranes. These microcapsules, which contained bacterial cells, were transferred into a column vessel and were incubated for 14 days to form microcolonies within the microcapsules. The cultured microcapsules were analyzed by flow cytometry, and the microbial colonized capsules were separated from free-living cells and empty capsules, based on the distinctive light-scattering signature of the microcapsules. The result showed that membrane emulsification preserved the viability of cells and this method was effective to create niches for various bacterial cells growing in high-throughput cultivation vessels. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800011r

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Peptides as functional surfactants / Annette F. Dexter in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6391–6398 Titre : Peptides as functional surfactants Type de document : texte imprimé Auteurs : Annette F. Dexter, Auteur ; Anton P. J. Middelberg, Auteur Année de publication : 2008 Article en page(s) : p. 6391–6398 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Surface-active peptides Lipopeptides Résumé : Peptides offer interesting alternatives to conventional surfactants in applications where renewability, biocompatibility, or added functionality may be desired. This review offers a brief overview of different classes of surface-active peptides and lipopeptides, covering molecules obtained from natural sources as well as those obtained by design. Bacterial lipopeptides are cyclic molecules containing a single fatty acyl moiety, which can exhibit ultralow interfacial tension as well as antimicrobial activities. Bacterial lipopeptides have been proposed for industrial applications such as bioremediation and oil recovery, but they suffer the dual disadvantages of being difficult to bioproduce at low cost and not being easily genetically engineered. A class of synthetic molecules related to bacterial lipopeptides are the peptide amphiphiles, in which a peptide headgroup is combined with a peptide or nonpeptide hydrophobic tail. Self-assembly of peptide amphiphiles has largely been studied in bulk solution rather than at interfaces, meaning that very little information is available on the interfacial properties of these designer molecules. A larger body of information is available for protein hydrolysates, products of the partial breakdown of low-cost proteins (usually food proteins) into a complex mixture of small peptides. Partial hydrolysis can improve the functional properties of many proteins, but the outcomes are difficult to predict or control, and useful functional properties may be associated with only a few minor components in the digest mix. Finally, designed peptide surfactants (Pepfactants), recently reported by the authors, are facially amphipathic molecules that self-assemble at fluid interfaces to give cohesive films stabilizing foams and emulsions. A change in the bulk solution conditions can switch off the interfacial film, leading to rapid foam or emulsion collapse. Pepfactants can be genetically engineered and bioproduced using standard methods, which represents an advantage over bacterial lipopeptides. While peptides have not been widely used in surfactant applications so far, recent developments may facilitate the incorporation of these interesting molecules into industrial and consumer products in the near future. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800127f [article] Peptides as functional surfactants [texte imprimé] / Annette F. Dexter, Auteur ; Anton P. J. Middelberg, Auteur . - 2008 . - p. 6391–6398. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6391–6398 Mots-clés : Surface-active peptides Lipopeptides Résumé : Peptides offer interesting alternatives to conventional surfactants in applications where renewability, biocompatibility, or added functionality may be desired. This review offers a brief overview of different classes of surface-active peptides and lipopeptides, covering molecules obtained from natural sources as well as those obtained by design. Bacterial lipopeptides are cyclic molecules containing a single fatty acyl moiety, which can exhibit ultralow interfacial tension as well as antimicrobial activities. Bacterial lipopeptides have been proposed for industrial applications such as bioremediation and oil recovery, but they suffer the dual disadvantages of being difficult to bioproduce at low cost and not being easily genetically engineered. A class of synthetic molecules related to bacterial lipopeptides are the peptide amphiphiles, in which a peptide headgroup is combined with a peptide or nonpeptide hydrophobic tail. Self-assembly of peptide amphiphiles has largely been studied in bulk solution rather than at interfaces, meaning that very little information is available on the interfacial properties of these designer molecules. A larger body of information is available for protein hydrolysates, products of the partial breakdown of low-cost proteins (usually food proteins) into a complex mixture of small peptides. Partial hydrolysis can improve the functional properties of many proteins, but the outcomes are difficult to predict or control, and useful functional properties may be associated with only a few minor components in the digest mix. Finally, designed peptide surfactants (Pepfactants), recently reported by the authors, are facially amphipathic molecules that self-assemble at fluid interfaces to give cohesive films stabilizing foams and emulsions. A change in the bulk solution conditions can switch off the interfacial film, leading to rapid foam or emulsion collapse. Pepfactants can be genetically engineered and bioproduced using standard methods, which represents an advantage over bacterial lipopeptides. While peptides have not been widely used in surfactant applications so far, recent developments may facilitate the incorporation of these interesting molecules into industrial and consumer products in the near future. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800127f

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Strategies for the design of hydrophilic microspheres with controlled size and microstructure / Huanhuan Qu in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6399–6404 Titre : Strategies for the design of hydrophilic microspheres with controlled size and microstructure Type de document : texte imprimé Auteurs : Huanhuan Qu, Auteur ; Fangling Gong, Auteur ; Jing Wang, Auteur Année de publication : 2008 Article en page(s) : p. 6399–6404 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrophilic microspheres Membrane emulsification Droplets swelling method PHEMA Résumé : Synthesizing hydrophilic microspheres is a subject of great interest for a variety of applications. However, there is difficulty in the control of the microspheresʼ size. In this study, the combination of membrane emulsification and droplets swelling method is utilized to prepare poly(2-hydroxyethylmethacrylate) (PHEMA) microspheres, a kind of hydrophilic material. The former is used to prepare monodisperse seed droplets, which include hydrophobic monomer (ethylenedimethacrylate, EDMA) and some assistant agents, whereas the latter is used for the absorption of hydrophilic monomer (HEMA). After a polymerization process, PHEMA microspheres with desired size can be obtained. It is found that large membrane pore size or high swelling ratio tended to increase the final particle size. At the same time, smaller particle size is got at higher EDMA concentration in the seed droplets. In addition, microstructure of the microspheres is also controlled by using this method. Nonporous, porous, nonporous/porous half-moon, or macroporous microspheres can be obtained easily by changing the total oil composition in swollen droplets. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800094a [article] Strategies for the design of hydrophilic microspheres with controlled size and microstructure [texte imprimé] / Huanhuan Qu, Auteur ; Fangling Gong, Auteur ; Jing Wang, Auteur . - 2008 . - p. 6399–6404. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6399–6404 Mots-clés : Hydrophilic microspheres Membrane emulsification Droplets swelling method PHEMA Résumé : Synthesizing hydrophilic microspheres is a subject of great interest for a variety of applications. However, there is difficulty in the control of the microspheresʼ size. In this study, the combination of membrane emulsification and droplets swelling method is utilized to prepare poly(2-hydroxyethylmethacrylate) (PHEMA) microspheres, a kind of hydrophilic material. The former is used to prepare monodisperse seed droplets, which include hydrophobic monomer (ethylenedimethacrylate, EDMA) and some assistant agents, whereas the latter is used for the absorption of hydrophilic monomer (HEMA). After a polymerization process, PHEMA microspheres with desired size can be obtained. It is found that large membrane pore size or high swelling ratio tended to increase the final particle size. At the same time, smaller particle size is got at higher EDMA concentration in the seed droplets. In addition, microstructure of the microspheres is also controlled by using this method. Nonporous, porous, nonporous/porous half-moon, or macroporous microspheres can be obtained easily by changing the total oil composition in swollen droplets. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800094a

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Formulation of controlled size PUFA-loaded oil-in-water emulsions by microchannel emulsification using β-carotene-rich palm oil / Marcos A. Neves in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6405–6411 Titre : Formulation of controlled size PUFA-loaded oil-in-water emulsions by microchannel emulsification using β-carotene-rich palm oil Type de document : texte imprimé Auteurs : Marcos A. Neves, Auteur ; Henelyta S. Ribeiro, Auteur ; Katerina B. Fujiu, Auteur Année de publication : 2008 Article en page(s) : p. 6405–6411 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyunsaturated fatty acids Oil-in-water emulsions Palm oil Microchannel emulsification Résumé : The purpose of this research was to produce size-controlled polyunsaturated fatty acids (PUFA)-loaded oil-in-water (O/W) emulsions using refined palm oil rich in β-carotene, by microchannel (MC) emulsification. A commercial mixture of long-chain PUFA extracted from Menhaden oil was added to palm oil at a concentration of 45 g/L and used as the to-be-dispersed phase. The continuous phase consisted of a water dispersion of two different emulsifiers, in order to improve droplet stabilization and β-carotene bioavailability: sucrose laurate and β-lactoglobulin (1 wt %, respectively). The effect of various levels of to-be-dispersed phase flux (Jd) (10, 20, 40, and 80 L/(m2·h)) and continuous phase flow velocity (V̅c) (ranging from 0.23 to 2.33 mm/s) on the behavior of droplet formation, average droplet size (dav) and coefficient of variation (CV) were evaluated. The fine carotenoid O/W emulsions loaded with PUFA were prepared using an MC emulsification device. Protein-stabilized monodispersed PUFA-loaded emulsions were successfully produced, with a dav of 27.9 μm and a CV of less than 4%. The dav and CV increased with Jd especially above 40 L/(m2·h), and were independent of V̅c, within the velocity range applied in this study. Analysis of the dimensionless Ca indicated that on increasing the Jd up to the critical Ca (0.075), the flow is based on spontaneous transformation, resulting in monodispersed droplets. If Ca exceeds the critical value, viscous force is dominant, the flow is similar to laminar flow, and the to-be-dispersed phase flows out continuously from the MC. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071552u [article] Formulation of controlled size PUFA-loaded oil-in-water emulsions by microchannel emulsification using β-carotene-rich palm oil [texte imprimé] / Marcos A. Neves, Auteur ; Henelyta S. Ribeiro, Auteur ; Katerina B. Fujiu, Auteur . - 2008 . - p. 6405–6411. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6405–6411 Mots-clés : Polyunsaturated fatty acids Oil-in-water emulsions Palm oil Microchannel emulsification Résumé : The purpose of this research was to produce size-controlled polyunsaturated fatty acids (PUFA)-loaded oil-in-water (O/W) emulsions using refined palm oil rich in β-carotene, by microchannel (MC) emulsification. A commercial mixture of long-chain PUFA extracted from Menhaden oil was added to palm oil at a concentration of 45 g/L and used as the to-be-dispersed phase. The continuous phase consisted of a water dispersion of two different emulsifiers, in order to improve droplet stabilization and β-carotene bioavailability: sucrose laurate and β-lactoglobulin (1 wt %, respectively). The effect of various levels of to-be-dispersed phase flux (Jd) (10, 20, 40, and 80 L/(m2·h)) and continuous phase flow velocity (V̅c) (ranging from 0.23 to 2.33 mm/s) on the behavior of droplet formation, average droplet size (dav) and coefficient of variation (CV) were evaluated. The fine carotenoid O/W emulsions loaded with PUFA were prepared using an MC emulsification device. Protein-stabilized monodispersed PUFA-loaded emulsions were successfully produced, with a dav of 27.9 μm and a CV of less than 4%. The dav and CV increased with Jd especially above 40 L/(m2·h), and were independent of V̅c, within the velocity range applied in this study. Analysis of the dimensionless Ca indicated that on increasing the Jd up to the critical Ca (0.075), the flow is based on spontaneous transformation, resulting in monodispersed droplets. If Ca exceeds the critical value, viscous force is dominant, the flow is similar to laminar flow, and the to-be-dispersed phase flows out continuously from the MC. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071552u

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Investigation on the uniformity and stability of sunflower oil/water emulsions prepared by a shirasu porous glass membrane / Yueling Zhang in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6412–6417 Titre : Investigation on the uniformity and stability of sunflower oil/water emulsions prepared by a shirasu porous glass membrane Type de document : texte imprimé Auteurs : Yueling Zhang, Auteur ; Guoping Lian, Auteur ; Shiping Zhu, Auteur Année de publication : 2008 Article en page(s) : p. 6412–6417 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : SPG membrane emulsification Sunflower oil emulsions Résumé : Shirasu porous glass (SPG) membrane emulsification has many advantages over traditional emulsification methods of stirring, ultrasoubd, and homogenization. The main advantages are much improved uniform size distribution of the droplets and lower mechanical shear stress. This paper examines the uniformity and stability of sunflower oil emulsions prepared by SPG membrane. The effects of emulsifiers on the uniformity and stability of emulsions were investigated. Results showed that emulsions stabilized by Tween 20 are generally more uniform and stable compared to those stabilized by Tween 60. Emulsions prepared by membrane emulsification showed excellent uniformity and stability with no droplet size change after 6-months storage, while those prepared by the homogenizer have a much broad size distribution and are unstable after 7 days of storage with significant further broadening of the droplet size distribution by coalescence and Oswald ripening. Uniform-sized sunflower O/W emulsions prepared by the SPG membrane also have good thermal stability when subjected to either freezing or heating. The mechanical stability of sunflower O/W emulsions prepared by the SPG membrane can be further improved by adding thickeners to the aqueous phase. Therefore, SPG membrane emulsification is a promising method for preparing uniform and stable emulsions, which will have good potential applications in the food industry, in terms of improving shelf life and product quality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002232 [article] Investigation on the uniformity and stability of sunflower oil/water emulsions prepared by a shirasu porous glass membrane [texte imprimé] / Yueling Zhang, Auteur ; Guoping Lian, Auteur ; Shiping Zhu, Auteur . - 2008 . - p. 6412–6417. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6412–6417 Mots-clés : SPG membrane emulsification Sunflower oil emulsions Résumé : Shirasu porous glass (SPG) membrane emulsification has many advantages over traditional emulsification methods of stirring, ultrasoubd, and homogenization. The main advantages are much improved uniform size distribution of the droplets and lower mechanical shear stress. This paper examines the uniformity and stability of sunflower oil emulsions prepared by SPG membrane. The effects of emulsifiers on the uniformity and stability of emulsions were investigated. Results showed that emulsions stabilized by Tween 20 are generally more uniform and stable compared to those stabilized by Tween 60. Emulsions prepared by membrane emulsification showed excellent uniformity and stability with no droplet size change after 6-months storage, while those prepared by the homogenizer have a much broad size distribution and are unstable after 7 days of storage with significant further broadening of the droplet size distribution by coalescence and Oswald ripening. Uniform-sized sunflower O/W emulsions prepared by the SPG membrane also have good thermal stability when subjected to either freezing or heating. The mechanical stability of sunflower O/W emulsions prepared by the SPG membrane can be further improved by adding thickeners to the aqueous phase. Therefore, SPG membrane emulsification is a promising method for preparing uniform and stable emulsions, which will have good potential applications in the food industry, in terms of improving shelf life and product quality. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002232

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Controlling factors on droplets uniformity in membrane emulsification / Dong-Xia Hao in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6418–6425 Titre : Controlling factors on droplets uniformity in membrane emulsification : experiment and modeling analysis Type de document : texte imprimé Auteurs : Dong-Xia Hao, Auteur ; Fang-Ling Gong, Auteur ; Guo-Hua Hu, Auteur Année de publication : 2008 Article en page(s) : p. 6418–6425 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Membrane emulsification Oil-in-water emulsion Droplet size distribution Résumé : The membrane emulsification process is attracting great interest in many industrial fields. For optimization and scaling up of the emulsification process, controlling the emulsion uniformity using monitoring process and membrane parameters is especially important. In this study, the effects of phase physical property (viscosity, interfacial tension), and operation conditions (trans-membrane pressure shear stress), on droplet size distribution of an oil-in-water (o/w) emulsion were systemically investigated by membrane emulsification experiments with a cross-flowing continuous phase. Inspired by the idea that droplet spontaneous formation is one of the most important mechanisms to form a uniform emulsion, a simple model based on torque balance equations by describing the variable force torques on droplet formation process was proposed to predict experimental tendencies. The experiment phenomena showed a good coincidence with model prediction. The following experiment conditions were found to facilitate the production of uniform droplets: (1) low cross-flow velocity of the continuous phase, (2) low transmembrane pressure, (3) high viscosity of the dispersed phase, and (4) an emulsifier with great ability and rapid rate to decrease interfacial tension. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000315 [article] Controlling factors on droplets uniformity in membrane emulsification : experiment and modeling analysis [texte imprimé] / Dong-Xia Hao, Auteur ; Fang-Ling Gong, Auteur ; Guo-Hua Hu, Auteur . - 2008 . - p. 6418–6425. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6418–6425 Mots-clés : Membrane emulsification Oil-in-water emulsion Droplet size distribution Résumé : The membrane emulsification process is attracting great interest in many industrial fields. For optimization and scaling up of the emulsification process, controlling the emulsion uniformity using monitoring process and membrane parameters is especially important. In this study, the effects of phase physical property (viscosity, interfacial tension), and operation conditions (trans-membrane pressure shear stress), on droplet size distribution of an oil-in-water (o/w) emulsion were systemically investigated by membrane emulsification experiments with a cross-flowing continuous phase. Inspired by the idea that droplet spontaneous formation is one of the most important mechanisms to form a uniform emulsion, a simple model based on torque balance equations by describing the variable force torques on droplet formation process was proposed to predict experimental tendencies. The experiment phenomena showed a good coincidence with model prediction. The following experiment conditions were found to facilitate the production of uniform droplets: (1) low cross-flow velocity of the continuous phase, (2) low transmembrane pressure, (3) high viscosity of the dispersed phase, and (4) an emulsifier with great ability and rapid rate to decrease interfacial tension. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8000315

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Behavior of cationic surfactants in poly(styrene sulfonate) brushes / Akira Ishikubo in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6426–6433 Titre : Behavior of cationic surfactants in poly(styrene sulfonate) brushes Type de document : texte imprimé Auteurs : Akira Ishikubo, Auteur ; Jimmy Mays, Auteur ; Matthew Tirrell, Auteur Année de publication : 2008 Article en page(s) : p. 6426–6433 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cationic surfactant Adsorption Electrostatic interactions Hydrophobic Résumé : The adsorption behavior of a cationic surfactant (cetyl trimethyl ammonium bromide, CTAB) in a sodium poly(styrene sulfonate) (NaPSS) brush in the presence of 1 mM NaNO3 was investigated by ellipsometry. The interactions between surfactants and brush chains determined from these results are compared with data from other types of experiments on similar systems. Four adsorption regimes were found, including regimes dominated by electrostatic interactions and by hydrophobic interactions. As the concentration of the surfactant increased from zero in the bulk solution surrounding the PSS brush, (1) surfactant monomers replaced Na+ ions reversibly, in a manner analogous to ion exchange, until β (the ratio of the number of bound surfactants to the total number of negatively charged monomers of PSS) reached 0.2−0.3 (1 × 10−6 M CTAB), (2) surfactants in the brushes interacted with each other hydrophobically, making adsorption irreversible and producing contraction of the brush (0.3 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800004w [article] Behavior of cationic surfactants in poly(styrene sulfonate) brushes [texte imprimé] / Akira Ishikubo, Auteur ; Jimmy Mays, Auteur ; Matthew Tirrell, Auteur . - 2008 . - p. 6426–6433. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6426–6433 Mots-clés : Cationic surfactant Adsorption Electrostatic interactions Hydrophobic Résumé : The adsorption behavior of a cationic surfactant (cetyl trimethyl ammonium bromide, CTAB) in a sodium poly(styrene sulfonate) (NaPSS) brush in the presence of 1 mM NaNO3 was investigated by ellipsometry. The interactions between surfactants and brush chains determined from these results are compared with data from other types of experiments on similar systems. Four adsorption regimes were found, including regimes dominated by electrostatic interactions and by hydrophobic interactions. As the concentration of the surfactant increased from zero in the bulk solution surrounding the PSS brush, (1) surfactant monomers replaced Na+ ions reversibly, in a manner analogous to ion exchange, until β (the ratio of the number of bound surfactants to the total number of negatively charged monomers of PSS) reached 0.2−0.3 (1 × 10−6 M CTAB), (2) surfactants in the brushes interacted with each other hydrophobically, making adsorption irreversible and producing contraction of the brush (0.3 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800004w

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Formation, stability, and rheology of particle stabilized emulsions / W. J. Frith in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6434–6444 Titre : Formation, stability, and rheology of particle stabilized emulsions : influence of multivalent cations Type de document : texte imprimé Auteurs : W. J. Frith, Auteur ; R. Pichot, Auteur ; M. Kirkland, Auteur Année de publication : 2008 Article en page(s) : p. 6434–6444 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oil/Water emulsions Hydrophilic colloidal silica particles Rheology Résumé : Recently, it has been shown that hydrophilic colloidal silica particles (Ludox) can be rendered sufficiently hydrophobic to stabilize oil in water (O/W) emulsions simply by changing the pH of the suspending medium to ∼2, and such emulsions have been shown to display novel rheology (shear thickening) compared to conventional emulsions (Wolf et al. J. Rheol., 2007, 51, 465). However, while lowering pH can render nanosized silica (∼10 nm) sufficiently hydrophobic so as to stabilize O/W emulsions, this method does not appear to generalize to larger silica particles (∼200 nm). In this present study, we explore a different approach, which employs hydrophilic, (i.e., not surface modified) colloidal silica particles to stabilize O/W emulsions in the presence of a range of cations. It appears that certain cations at high pH (in particular La3+) will render various inorganic oxide surfaces more hydrophobic. As such this makes the combination of silica particles with appropriate concentrations of Lanthanum cations an attractive model system for the study of the formulation, stability, and rheological behavior of Pickering emulsions. We present initial investigations exploring the formulation of such emulsions and of how their rheology and stability compare with more conventional emulsions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071629e [article] Formation, stability, and rheology of particle stabilized emulsions : influence of multivalent cations [texte imprimé] / W. J. Frith, Auteur ; R. Pichot, Auteur ; M. Kirkland, Auteur . - 2008 . - p. 6434–6444. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6434–6444 Mots-clés : Oil/Water emulsions Hydrophilic colloidal silica particles Rheology Résumé : Recently, it has been shown that hydrophilic colloidal silica particles (Ludox) can be rendered sufficiently hydrophobic to stabilize oil in water (O/W) emulsions simply by changing the pH of the suspending medium to ∼2, and such emulsions have been shown to display novel rheology (shear thickening) compared to conventional emulsions (Wolf et al. J. Rheol., 2007, 51, 465). However, while lowering pH can render nanosized silica (∼10 nm) sufficiently hydrophobic so as to stabilize O/W emulsions, this method does not appear to generalize to larger silica particles (∼200 nm). In this present study, we explore a different approach, which employs hydrophilic, (i.e., not surface modified) colloidal silica particles to stabilize O/W emulsions in the presence of a range of cations. It appears that certain cations at high pH (in particular La3+) will render various inorganic oxide surfaces more hydrophobic. As such this makes the combination of silica particles with appropriate concentrations of Lanthanum cations an attractive model system for the study of the formulation, stability, and rheological behavior of Pickering emulsions. We present initial investigations exploring the formulation of such emulsions and of how their rheology and stability compare with more conventional emulsions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071629e

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Effect of polymer polarity on the shape of “golf ball-like” particles prepared by seeded dispersion polymerization / Teruhisa Fujibayashi in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6445–6449 Titre : Effect of polymer polarity on the shape of “golf ball-like” particles prepared by seeded dispersion polymerization Type de document : texte imprimé Auteurs : Teruhisa Fujibayashi, Auteur ; Yoshifumi Komatsu, Auteur ; Natsumi Konishi, Auteur Année de publication : 2008 Article en page(s) : p. 6445–6449 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Golf ball-like particles n-butyl methacrylate Dimples Résumé : Micrometer-sized, monodisperse, ”golf ball-like” particles that have numerous dimples at the surfaces were prepared by seeded dispersion polymerization of n-butyl methacrylate (n-BMA), with polystyrene/poly(styrene-co-sodium styrene sulfonate) composite particles as seed, in the presence of dodecane droplets in a methanol/water (80/20, w/w) medium, followed by the evaporation of dodecane. The dimples at the surface were formed by the volume reduction of poly(n-BMA)/dodecane (Pn-BMA/dodecane) domains, because of the evaporation of the dodecane. The size and number of dimples at the surfaces of the obtained golf ball-like particles decreased as the sodium styrene sulfonate content of the seed particles increased. The Pn-BMA/dodecane domains were engulfed deeper in the surface layer of the seed particle, and, thus, dimples became apparently smaller at the surface with an increase in the hydrophilicity of the surface of the seed particle. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800188f [article] Effect of polymer polarity on the shape of “golf ball-like” particles prepared by seeded dispersion polymerization [texte imprimé] / Teruhisa Fujibayashi, Auteur ; Yoshifumi Komatsu, Auteur ; Natsumi Konishi, Auteur . - 2008 . - p. 6445–6449. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6445–6449 Mots-clés : Golf ball-like particles n-butyl methacrylate Dimples Résumé : Micrometer-sized, monodisperse, ”golf ball-like” particles that have numerous dimples at the surfaces were prepared by seeded dispersion polymerization of n-butyl methacrylate (n-BMA), with polystyrene/poly(styrene-co-sodium styrene sulfonate) composite particles as seed, in the presence of dodecane droplets in a methanol/water (80/20, w/w) medium, followed by the evaporation of dodecane. The dimples at the surface were formed by the volume reduction of poly(n-BMA)/dodecane (Pn-BMA/dodecane) domains, because of the evaporation of the dodecane. The size and number of dimples at the surfaces of the obtained golf ball-like particles decreased as the sodium styrene sulfonate content of the seed particles increased. The Pn-BMA/dodecane domains were engulfed deeper in the surface layer of the seed particle, and, thus, dimples became apparently smaller at the surface with an increase in the hydrophilicity of the surface of the seed particle. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800188f

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Reactive binders in detergent granulation / Sarah Germanà in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6450–6458 Titre : Reactive binders in detergent granulation : understanding the relationship between binder phase changes and granule growth under different conditions of relative humidity Type de document : texte imprimé Auteurs : Sarah Germanà, Auteur ; Stefaan J. R. Simons, Auteur ; Judith Bonsall, Auteur Année de publication : 2008 Article en page(s) : p. 6450–6458 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reactive binder Detergent granulation Résumé : The increasing tendency to enhance consumer products with added functionality is leading to ever more complex products that are manufactured at large scale in conventional processes. Hence, it is important that process operating conditions are matched to the product requirements. We report on the fundamental characteristics of the reactive binder, LAS acid (HLAS), used in detergent granulation, in relation to its wetting behavior and viscosity as it is neutralized by its reaction with sodium carbonate, and how the phase changes are affected by relative humidity (RH) and temperature, in order to establish the relationship between the binder phase changes and granule formation and growth. We have found that the higher the degree of neutralization, the lower the tendency of the liquid to wet the particles (the binder behaves as a sticky paste) and that wetting behavior is strongly dependent on RH. The latter highlights the importance of controlling the environmental conditions during processing and storage of the materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800280k [article] Reactive binders in detergent granulation : understanding the relationship between binder phase changes and granule growth under different conditions of relative humidity [texte imprimé] / Sarah Germanà, Auteur ; Stefaan J. R. Simons, Auteur ; Judith Bonsall, Auteur . - 2008 . - p. 6450–6458. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6450–6458 Mots-clés : Reactive binder Detergent granulation Résumé : The increasing tendency to enhance consumer products with added functionality is leading to ever more complex products that are manufactured at large scale in conventional processes. Hence, it is important that process operating conditions are matched to the product requirements. We report on the fundamental characteristics of the reactive binder, LAS acid (HLAS), used in detergent granulation, in relation to its wetting behavior and viscosity as it is neutralized by its reaction with sodium carbonate, and how the phase changes are affected by relative humidity (RH) and temperature, in order to establish the relationship between the binder phase changes and granule formation and growth. We have found that the higher the degree of neutralization, the lower the tendency of the liquid to wet the particles (the binder behaves as a sticky paste) and that wetting behavior is strongly dependent on RH. The latter highlights the importance of controlling the environmental conditions during processing and storage of the materials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800280k

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Crack formation in drying laponite / Sujata Tarafdar in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6459–6464 Titre : Crack formation in drying laponite Type de document : texte imprimé Auteurs : Sujata Tarafdar, Auteur ; Suparna Sinha, Auteur Année de publication : 2008 Article en page(s) : p. 6459–6464 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Crack patterns Laponite Résumé : Natural clay and other granular materials form crack networks with typical patterns on desiccation. The present paper reviews a series of studies on crack patterns produced by drying laponite suspensions in different solvents, on different substrates. Laponite is a synthetic clay composed of nanosized platelets of uniform size and composition. The area covered by the cracks shows a scaling behavior with layer thickness. The salient features of the experimental observations can be reproduced by a computer simulation with a chain of springs modeling the clay. We review earlier work done on crack patterns in drying laponite, suspended in methanol as well as water. Experiments on a modification of the setup where the samples are allowed to dry in an electric field are also reviewed. We present new results done on a different geometrical arrangement of the electrodes. The crack patterns are again found to follow the symmetry of the field. Another new observation is that gelation starts earlier when suspensions with excess water are placed in an electric field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071375x [article] Crack formation in drying laponite [texte imprimé] / Sujata Tarafdar, Auteur ; Suparna Sinha, Auteur . - 2008 . - p. 6459–6464. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6459–6464 Mots-clés : Crack patterns Laponite Résumé : Natural clay and other granular materials form crack networks with typical patterns on desiccation. The present paper reviews a series of studies on crack patterns produced by drying laponite suspensions in different solvents, on different substrates. Laponite is a synthetic clay composed of nanosized platelets of uniform size and composition. The area covered by the cracks shows a scaling behavior with layer thickness. The salient features of the experimental observations can be reproduced by a computer simulation with a chain of springs modeling the clay. We review earlier work done on crack patterns in drying laponite, suspended in methanol as well as water. Experiments on a modification of the setup where the samples are allowed to dry in an electric field are also reviewed. We present new results done on a different geometrical arrangement of the electrodes. The crack patterns are again found to follow the symmetry of the field. Another new observation is that gelation starts earlier when suspensions with excess water are placed in an electric field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071375x

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Use of “bricks and mortar” model to predict transdermal permeation / Longjian Chen in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6465–6472 Titre : Use of “bricks and mortar” model to predict transdermal permeation : model development and initial validation Type de document : texte imprimé Auteurs : Longjian Chen, Auteur ; Guoping Lian, Auteur ; Lujia Han, Auteur Année de publication : 2008 Article en page(s) : p. 6465–6472 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Transdermal permeation Bricks and mortar model Résumé : Presented in this paper is a general purpose computer model for predicting transdermal permeation of solutes in vivo. The “bricks and mortar” model is employed to represent the stratum corneum (SC), the main barrier to transdermal permeation. Transdermal permeation and absorption is modeled as a dynamic process of mass transfer in the heterogeneous stratum corneum including both the tortuous lipid pathway and the transcellular corneocytes pathway. The partition and diffusion properties of solutes in SC lipid matrix and corneocytes are calculated from the fundamental physical chemical properties of octanol−water partition coefficient, molecular size, and diffusion coefficients in water and lipid, using equations established elsewhere. To test the model, the in vivo tape striping data of 4-cyanophenol is simulated. Using the calculated partition and diffusion properties of 4-cyanophenol in SC lipids and corneocytes, the predicted dynamic profiles of 4-cyanophenol in the SC agreed very well with the experimental data. Results show that for a moderately hydrophobic solute like 4-cyanophenol, the transcellular pathway is also an important route of percutaneous absorption with about 2/3 of the absorbed 4-cyanophenol partitioned into the corneocytes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701711v [article] Use of “bricks and mortar” model to predict transdermal permeation : model development and initial validation [texte imprimé] / Longjian Chen, Auteur ; Guoping Lian, Auteur ; Lujia Han, Auteur . - 2008 . - p. 6465–6472. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6465–6472 Mots-clés : Transdermal permeation Bricks and mortar model Résumé : Presented in this paper is a general purpose computer model for predicting transdermal permeation of solutes in vivo. The “bricks and mortar” model is employed to represent the stratum corneum (SC), the main barrier to transdermal permeation. Transdermal permeation and absorption is modeled as a dynamic process of mass transfer in the heterogeneous stratum corneum including both the tortuous lipid pathway and the transcellular corneocytes pathway. The partition and diffusion properties of solutes in SC lipid matrix and corneocytes are calculated from the fundamental physical chemical properties of octanol−water partition coefficient, molecular size, and diffusion coefficients in water and lipid, using equations established elsewhere. To test the model, the in vivo tape striping data of 4-cyanophenol is simulated. Using the calculated partition and diffusion properties of 4-cyanophenol in SC lipids and corneocytes, the predicted dynamic profiles of 4-cyanophenol in the SC agreed very well with the experimental data. Results show that for a moderately hydrophobic solute like 4-cyanophenol, the transcellular pathway is also an important route of percutaneous absorption with about 2/3 of the absorbed 4-cyanophenol partitioned into the corneocytes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701711v

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Elastohydrodynamic suppression of free-surface instabilities in annular liquid film flow outside wires and inside tubes / Aashish Jain in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6473–6485 Titre : Elastohydrodynamic suppression of free-surface instabilities in annular liquid film flow outside wires and inside tubes Type de document : texte imprimé Auteurs : Aashish Jain, Auteur ; V. Shankar, Auteur Année de publication : 2008 Article en page(s) : p. 6473–6485 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Free-surface instability Low-wavenumber perturbation analysis Numerical method Résumé : The linear stability of gravity-driven annular liquid film flow outside wires and inside tubes is analyzed when the rigid surface is replaced by a deformable (neo-Hookean) solid wall. On a rigid surface, an annular liquid thread becomes unstable due to a Rayleigh-type capillary instability even in the absence of flow. In the presence of flow, the annular liquid film becomes unstable due to a flow-driven, free-surface instability, which occurs over and above the curvature-induced capillary instability. In this paper, a low-wavenumber perturbation analysis is first used to elucidate the effect of wall deformability on the free-surface instability. It is shown that the free-surface instability is completely stabilized in the low-wavenumber limit when the wall is made sufficiently deformable. A numerical method is subsequently used to determine the stability of the system at arbitrary wavenumbers. Results from the numerical solution reveal that the prediction of instability suppression at low wavenumbers extends to finite wavenumbers as well. However, as the solid wall is made deformable even further, the free surface is destabilized at finite wavenumbers by the deformability; in addition, the liquid−solid interface could also become unstable when the solid deformability becomes high. It is demonstrated, however, that there is a sufficient range of shear modulus of the solid where the annular flow is stable at all wavenumbers. The results of this study have implications in wire-coating operations, as well as in biological settings such as closure of lung airways. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701771m [article] Elastohydrodynamic suppression of free-surface instabilities in annular liquid film flow outside wires and inside tubes [texte imprimé] / Aashish Jain, Auteur ; V. Shankar, Auteur . - 2008 . - p. 6473–6485. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6473–6485 Mots-clés : Free-surface instability Low-wavenumber perturbation analysis Numerical method Résumé : The linear stability of gravity-driven annular liquid film flow outside wires and inside tubes is analyzed when the rigid surface is replaced by a deformable (neo-Hookean) solid wall. On a rigid surface, an annular liquid thread becomes unstable due to a Rayleigh-type capillary instability even in the absence of flow. In the presence of flow, the annular liquid film becomes unstable due to a flow-driven, free-surface instability, which occurs over and above the curvature-induced capillary instability. In this paper, a low-wavenumber perturbation analysis is first used to elucidate the effect of wall deformability on the free-surface instability. It is shown that the free-surface instability is completely stabilized in the low-wavenumber limit when the wall is made sufficiently deformable. A numerical method is subsequently used to determine the stability of the system at arbitrary wavenumbers. Results from the numerical solution reveal that the prediction of instability suppression at low wavenumbers extends to finite wavenumbers as well. However, as the solid wall is made deformable even further, the free surface is destabilized at finite wavenumbers by the deformability; in addition, the liquid−solid interface could also become unstable when the solid deformability becomes high. It is demonstrated, however, that there is a sufficient range of shear modulus of the solid where the annular flow is stable at all wavenumbers. The results of this study have implications in wire-coating operations, as well as in biological settings such as closure of lung airways. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701771m

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Sorption-enhanced hydrogen production / Douglas P. Harrison in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6486–6501 Titre : Sorption-enhanced hydrogen production : a review Type de document : texte imprimé Auteurs : Douglas P. Harrison, Auteur Année de publication : 2008 Article en page(s) : p. 6486–6501 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sorption-enhanced hydrogen production CO2 sorbent Water gas shift reactions Résumé : In the sorption-enhanced hydrogen production process, hydrocarbon reforming, water gas shift, and CO2 separation reactions occur simultaneously in a single reaction step over a reforming catalyst mixed with a CO2 sorbent. Transferring CO2 as it is formed from the gas to the solid phase shifts the normal equilibrium restrictions and allows both the reforming and water gas shift reactions to approach completion. Depending on reaction conditions, the product (dry basis) may contain as much as 98% H2 and only ppmv levels of CO and CO2, thereby minimizing the final H2 purification step or even eliminating it for some applications. A number of CO2 sorbents have been studied including calcium-based oxides, K-promoted hydrotalcite, and mixed metal oxides of lithium and sodium. The sorbent is consumed during H2 production so that the process is intrinsically unsteady state. Process economics requires that the sorbent be regenerable and used in many reaction−regeneration cycles. Regeneration may occur via temperature swing, pressure swing, or a combination. Much of the current research is devoted to testing and improving sorbent multicycle durability. Both circulating fluid-bed reactors and dual fixed-bed reactors with alternating reaction−regeneration functions have been proposed to provide overall steady state H2 production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800298z [article] Sorption-enhanced hydrogen production : a review [texte imprimé] / Douglas P. Harrison, Auteur . - 2008 . - p. 6486–6501. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6486–6501 Mots-clés : Sorption-enhanced hydrogen production CO2 sorbent Water gas shift reactions Résumé : In the sorption-enhanced hydrogen production process, hydrocarbon reforming, water gas shift, and CO2 separation reactions occur simultaneously in a single reaction step over a reforming catalyst mixed with a CO2 sorbent. Transferring CO2 as it is formed from the gas to the solid phase shifts the normal equilibrium restrictions and allows both the reforming and water gas shift reactions to approach completion. Depending on reaction conditions, the product (dry basis) may contain as much as 98% H2 and only ppmv levels of CO and CO2, thereby minimizing the final H2 purification step or even eliminating it for some applications. A number of CO2 sorbents have been studied including calcium-based oxides, K-promoted hydrotalcite, and mixed metal oxides of lithium and sodium. The sorbent is consumed during H2 production so that the process is intrinsically unsteady state. Process economics requires that the sorbent be regenerable and used in many reaction−regeneration cycles. Regeneration may occur via temperature swing, pressure swing, or a combination. Much of the current research is devoted to testing and improving sorbent multicycle durability. Both circulating fluid-bed reactors and dual fixed-bed reactors with alternating reaction−regeneration functions have been proposed to provide overall steady state H2 production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800298z

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Mechanistic study of the ZEA organic pollutant degradation system / Derek F. Laine in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6502–6508 Titre : Mechanistic study of the ZEA organic pollutant degradation system : evidence for H2O2, HO•, and the homogeneous activation of O2 by feIIEDTA Type de document : texte imprimé Auteurs : Derek F. Laine, Auteur ; Alexander Blumenfeld, Auteur ; I. Francis Cheng, Auteur Année de publication : 2008 Article en page(s) : p. 6502–6508 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : ZEA system Electrochemical model Carbon basket electrode Résumé : The ZEA (zero valent iron, ethylenediaminetetraacetic acid (EDTA), and air) organic pollutant degradation system has been previously shown to degrade a variety of organic pollutants and chemical warfare agent surrogates; however, mechanistic details and reactive intermediates formed in this system have not been identified. It is hypothesized that the ZEA system produces reactive oxygen species (H2O2, HO•) by the reduction of oxygen by FeIIEDTA(aq). This hypothesis is examined through an electrochemical model of the ZEA system. A carbon basket electrode is used as the reducing agent in place of Fe(0). The FeIIIEDTA complex (0.5 mM) is electrochemically reduced to FeIIEDTA at an applied potential of −120 mV (vs Ag/AgCl) under aerobic conditions. Hydrogen peroxide was observed to form in the presence of the metal complex with a maximum concentration reaching 0.139 mM H2O2 after 3 h of electrolysis. In the absence of FeEDTA, 0.04 mM H2O2 is obtained by the direct reduction of O2 at the electrode surface. Electron resonance spectroscopy (ESR), along with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap and methanol as a radical scavenger confirms the formation of HO• produced via the Fenton reaction in the electrochemical system. Hydroxyl radical attack on EDTA caused the degradation of FeII/IIIEDTA to a steady-state concentration of 0.14 mM from 0.5 mM as observed by HPLC. The pH of the electrolysis solution increased from 2.64 to 9.25 during 6 h of reductive electrolysis which is indicative of the consumption of H+ during the reduction of O2 to form H2O2. These experiments provide evidence that the ZEA system uses atmospheric O2 to produce reactive oxygen species including those that deeply oxidize organics under room temperature and pressure conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701676q [article] Mechanistic study of the ZEA organic pollutant degradation system : evidence for H2O2, HO•, and the homogeneous activation of O2 by feIIEDTA [texte imprimé] / Derek F. Laine, Auteur ; Alexander Blumenfeld, Auteur ; I. Francis Cheng, Auteur . - 2008 . - p. 6502–6508. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6502–6508 Mots-clés : ZEA system Electrochemical model Carbon basket electrode Résumé : The ZEA (zero valent iron, ethylenediaminetetraacetic acid (EDTA), and air) organic pollutant degradation system has been previously shown to degrade a variety of organic pollutants and chemical warfare agent surrogates; however, mechanistic details and reactive intermediates formed in this system have not been identified. It is hypothesized that the ZEA system produces reactive oxygen species (H2O2, HO•) by the reduction of oxygen by FeIIEDTA(aq). This hypothesis is examined through an electrochemical model of the ZEA system. A carbon basket electrode is used as the reducing agent in place of Fe(0). The FeIIIEDTA complex (0.5 mM) is electrochemically reduced to FeIIEDTA at an applied potential of −120 mV (vs Ag/AgCl) under aerobic conditions. Hydrogen peroxide was observed to form in the presence of the metal complex with a maximum concentration reaching 0.139 mM H2O2 after 3 h of electrolysis. In the absence of FeEDTA, 0.04 mM H2O2 is obtained by the direct reduction of O2 at the electrode surface. Electron resonance spectroscopy (ESR), along with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap and methanol as a radical scavenger confirms the formation of HO• produced via the Fenton reaction in the electrochemical system. Hydroxyl radical attack on EDTA caused the degradation of FeII/IIIEDTA to a steady-state concentration of 0.14 mM from 0.5 mM as observed by HPLC. The pH of the electrolysis solution increased from 2.64 to 9.25 during 6 h of reductive electrolysis which is indicative of the consumption of H+ during the reduction of O2 to form H2O2. These experiments provide evidence that the ZEA system uses atmospheric O2 to produce reactive oxygen species including those that deeply oxidize organics under room temperature and pressure conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701676q

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Microwave synthesis and photocatalytic activity of nano lanthanide (Ce, Pr, and Nd) orthovanadates / Sudarshan Mahapatra in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6509–6516 Titre : Microwave synthesis and photocatalytic activity of nano lanthanide (Ce, Pr, and Nd) orthovanadates Type de document : texte imprimé Auteurs : Sudarshan Mahapatra, Auteur ; Susanta K. Nayak, Auteur ; Giridhar Madras, Auteur Année de publication : 2008 Article en page(s) : p. 6509–6516 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Lanthanide orthovanadates Photocatalytic activities Crystal structure X-ray diffraction Résumé : Lanthanide orthovanadates, CeVO4, PrVO4, and NdVO4, of nanodimensions were synthesized under microwave exposure, and the photocatalytic activities of these compounds were investigated. These compounds exhibit a tetragonal zircon structure, crystallizing in the space group I41/amd with a = 7.3733(4) and c = 6.4909(4) Å with Z = 4. The crystal structure was analyzed by powder X-ray diffraction, and the band gap was analyzed by UV−visible spectroscopy. Particle sizes were in the range of 25−30 nm, as observed by transmission electron microscopy. While the energy dispersive X-ray analysis indicates the formation of LnVO4, thermal analysis of these solids shows stability of the phase up to 1000 °C. The photocatalytic activity of all these orthovanadates has been investigated by degrading various dyes like methylene blue (MB), Orange G (OG), Rhodamine B (RB), Rhodamine Blue (RBL), and Remazol brilliant blue (RBBR) under UV irradiation. Further, these compounds were also used to degrade organic pollutants like phenol, 2,4-dinitrophenol and 2,4-dichlorophenol. The degradation rates of dyes and organics in presence of microwave-synthesized orthovanadates are higher compared to that observed with orthovanadates synthesized by the solid state technique. The microwave-synthesized orthovandates also show chloro-specificity, with the rate of degradation of 2,4-dichlorophenol significantly higher than that observed in presence of Degussa P-25 titania. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003094 [article] Microwave synthesis and photocatalytic activity of nano lanthanide (Ce, Pr, and Nd) orthovanadates [texte imprimé] / Sudarshan Mahapatra, Auteur ; Susanta K. Nayak, Auteur ; Giridhar Madras, Auteur . - 2008 . - p. 6509–6516. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6509–6516 Mots-clés : Lanthanide orthovanadates Photocatalytic activities Crystal structure X-ray diffraction Résumé : Lanthanide orthovanadates, CeVO4, PrVO4, and NdVO4, of nanodimensions were synthesized under microwave exposure, and the photocatalytic activities of these compounds were investigated. These compounds exhibit a tetragonal zircon structure, crystallizing in the space group I41/amd with a = 7.3733(4) and c = 6.4909(4) Å with Z = 4. The crystal structure was analyzed by powder X-ray diffraction, and the band gap was analyzed by UV−visible spectroscopy. Particle sizes were in the range of 25−30 nm, as observed by transmission electron microscopy. While the energy dispersive X-ray analysis indicates the formation of LnVO4, thermal analysis of these solids shows stability of the phase up to 1000 °C. The photocatalytic activity of all these orthovanadates has been investigated by degrading various dyes like methylene blue (MB), Orange G (OG), Rhodamine B (RB), Rhodamine Blue (RBL), and Remazol brilliant blue (RBBR) under UV irradiation. Further, these compounds were also used to degrade organic pollutants like phenol, 2,4-dinitrophenol and 2,4-dichlorophenol. The degradation rates of dyes and organics in presence of microwave-synthesized orthovanadates are higher compared to that observed with orthovanadates synthesized by the solid state technique. The microwave-synthesized orthovandates also show chloro-specificity, with the rate of degradation of 2,4-dichlorophenol significantly higher than that observed in presence of Degussa P-25 titania. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003094

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Investigation into the roles of sulfur-containing amino acids in electroless nickel plating bath / Ke Wang in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6517–6524 Titre : Investigation into the roles of sulfur-containing amino acids in electroless nickel plating bath Type de document : texte imprimé Auteurs : Ke Wang, Auteur ; Liang Hong, Auteur ; Zhao-Lin Liu, Auteur Année de publication : 2008 Article en page(s) : p. 6517–6524 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sulfur-containing amino acids Electroless nickel plating Chemical adsorption Résumé : Typical sulfur-containing amino acids, cysteine and methionine, were employed as stabilizers in place of lead(II) acetate in the electroless nickel plating (ENP) system. Each of these compounds presents a critical stabilizing concentration of ca. 10−5 mol/L, below which the ENP rate is slightly promoted with increasing concentration but above which it is significantly suppressed. Their role in stabilizing the ENP bath was found to involve inhibition of the anodic reaction of hypophosphite. The chemical adsorption of these two amino acids on active nickel sites at the Ni plating surface was studied via their adsorption on an in situ generated Ni powder. In addition, the stabilization mechanism was investigated by using potentiometry, X-ray photoelectron spectroscopy (XPS), and UV−vis/infrared spectroscopy. Finally, the bath stabilizing capabilities of these two amino acids and the change in ENP properties with time were assessed through a continuous operation comprising four metal-turnover (MTO) runs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800456b [article] Investigation into the roles of sulfur-containing amino acids in electroless nickel plating bath [texte imprimé] / Ke Wang, Auteur ; Liang Hong, Auteur ; Zhao-Lin Liu, Auteur . - 2008 . - p. 6517–6524. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6517–6524 Mots-clés : Sulfur-containing amino acids Electroless nickel plating Chemical adsorption Résumé : Typical sulfur-containing amino acids, cysteine and methionine, were employed as stabilizers in place of lead(II) acetate in the electroless nickel plating (ENP) system. Each of these compounds presents a critical stabilizing concentration of ca. 10−5 mol/L, below which the ENP rate is slightly promoted with increasing concentration but above which it is significantly suppressed. Their role in stabilizing the ENP bath was found to involve inhibition of the anodic reaction of hypophosphite. The chemical adsorption of these two amino acids on active nickel sites at the Ni plating surface was studied via their adsorption on an in situ generated Ni powder. In addition, the stabilization mechanism was investigated by using potentiometry, X-ray photoelectron spectroscopy (XPS), and UV−vis/infrared spectroscopy. Finally, the bath stabilizing capabilities of these two amino acids and the change in ENP properties with time were assessed through a continuous operation comprising four metal-turnover (MTO) runs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800456b

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Aqueous metronidazole degradation by UV/H2O2 process in single-and multi-lamp tubular photoreactors / Melody Blythe Johnson in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6525–6537 Titre : Aqueous metronidazole degradation by UV/H2O2 process in single-and multi-lamp tubular photoreactors : kinetics and reactor design Type de document : texte imprimé Auteurs : Melody Blythe Johnson, Auteur ; Mehrab Mehrvar, Auteur Année de publication : 2008 Article en page(s) : p. 6525–6537 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Aqueous metronidazole Kinetic model UV/H2O2 process Résumé : A kinetic model was developed to predict the removal of aqueous metronidazole utilizing the UV/H2O2 process. The rate constant for the reaction between metronidazole and hydroxyl radicals was determined to be 1.98 × 109 M−1 s−1. The model was able to predict an optimal initial H2O2 dose and the inhibitory effects of high H2O2 doses and bicarbonate ions in the aqueous solution. Simulations were performed for three different photoreactors treating a 6 μM solution of metronidazole at various influent H2O2 doses and photoreactor radii. The predicted removal rates of metronidazole were 4.9−13% and 14−41% for the single-lamp and multilamp photoreactors, respectively. Selection of a photoreactor radius for maximum metronidazole removal varied with influent H2O2 concentration. The lowest operational cost of $0.05 per mmol removed was projected for the multilamp photoreactor. Operationally, it was cost-effective to utilize higher UV lamp output (36W), while keeping influent H2O2 concentration low (25 mg/L). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071637v [article] Aqueous metronidazole degradation by UV/H2O2 process in single-and multi-lamp tubular photoreactors : kinetics and reactor design [texte imprimé] / Melody Blythe Johnson, Auteur ; Mehrab Mehrvar, Auteur . - 2008 . - p. 6525–6537. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6525–6537 Mots-clés : Aqueous metronidazole Kinetic model UV/H2O2 process Résumé : A kinetic model was developed to predict the removal of aqueous metronidazole utilizing the UV/H2O2 process. The rate constant for the reaction between metronidazole and hydroxyl radicals was determined to be 1.98 × 109 M−1 s−1. The model was able to predict an optimal initial H2O2 dose and the inhibitory effects of high H2O2 doses and bicarbonate ions in the aqueous solution. Simulations were performed for three different photoreactors treating a 6 μM solution of metronidazole at various influent H2O2 doses and photoreactor radii. The predicted removal rates of metronidazole were 4.9−13% and 14−41% for the single-lamp and multilamp photoreactors, respectively. Selection of a photoreactor radius for maximum metronidazole removal varied with influent H2O2 concentration. The lowest operational cost of $0.05 per mmol removed was projected for the multilamp photoreactor. Operationally, it was cost-effective to utilize higher UV lamp output (36W), while keeping influent H2O2 concentration low (25 mg/L). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071637v

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Hydroisomerization of n-octane over bifunctional Ni-Pd/HY zeolite catalysts / Dhanapalan Karthikeyan in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6538–6546 Titre : Hydroisomerization of n-octane over bifunctional Ni-Pd/HY zeolite catalysts Type de document : texte imprimé Auteurs : Dhanapalan Karthikeyan, Auteur ; Nachiyappan Lingappan, Auteur ; Bommasamudram Sivasankar, Auteur Année de publication : 2008 Article en page(s) : p. 6538–6546 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : HY zeolite Incipient wetness impregnation X-ray diffraction BET surface area Résumé : Bifunctional catalysts containing 0.1−0.5 wt % nickel and 0.1 wt % palladium supported on HY zeolite were prepared through incipient wetness impregnation (IWI) and characterized by X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET) surface area, temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Hydroisomerization of n-octane was carried out between 200 and 450 °C under 1 atm of pressure, and it was found that Ni addition up to 0.3 wt % over 0.1 wt % Pd/HY zeolite enhanced the n-octane conversion and isomerization selectivity with a low percentage of cracked products. As the Ni amount exceeds the threshold values, the conversion decreases with an increase in cracked products, and also, the selectivity of mono- and dibranched isomers was improved, suggesting the operation of a protonated cyclopropane (PCP) intermediate mechanism. As a conclusion, the bimetallic catalysts were more selective toward the formation of dibranched isomers containing higher octane number. The role of noble metal over HY zeolite and recyclability of the catalyst were also studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017299 [article] Hydroisomerization of n-octane over bifunctional Ni-Pd/HY zeolite catalysts [texte imprimé] / Dhanapalan Karthikeyan, Auteur ; Nachiyappan Lingappan, Auteur ; Bommasamudram Sivasankar, Auteur . - 2008 . - p. 6538–6546. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6538–6546 Mots-clés : HY zeolite Incipient wetness impregnation X-ray diffraction BET surface area Résumé : Bifunctional catalysts containing 0.1−0.5 wt % nickel and 0.1 wt % palladium supported on HY zeolite were prepared through incipient wetness impregnation (IWI) and characterized by X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET) surface area, temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Hydroisomerization of n-octane was carried out between 200 and 450 °C under 1 atm of pressure, and it was found that Ni addition up to 0.3 wt % over 0.1 wt % Pd/HY zeolite enhanced the n-octane conversion and isomerization selectivity with a low percentage of cracked products. As the Ni amount exceeds the threshold values, the conversion decreases with an increase in cracked products, and also, the selectivity of mono- and dibranched isomers was improved, suggesting the operation of a protonated cyclopropane (PCP) intermediate mechanism. As a conclusion, the bimetallic catalysts were more selective toward the formation of dibranched isomers containing higher octane number. The role of noble metal over HY zeolite and recyclability of the catalyst were also studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie7017299

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Dimethyl ether synthesis from CO2 hydrogenation on a CuO-ZnO-Al2O3-ZrO2/HZSM-5 bifunctional catalyst / Xin An in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6547–6554 Titre : Dimethyl ether synthesis from CO2 hydrogenation on a CuO-ZnO-Al2O3-ZrO2/HZSM-5 bifunctional catalyst Type de document : texte imprimé Auteurs : Xin An, Auteur ; Yi-Zan Zuo, Auteur ; Qiang Zhang, Auteur Année de publication : 2008 Article en page(s) : p. 6547–6554 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dimethy ether synthesis CO2 hydrogenation Bifunctional catalyst Résumé : A CuO−ZnO−Al2O3−ZrO2 + HZSM-5 physical mixture bifunctional catalyst with a high activity for dimethy ether (DME) synthesis was used for CO2 hydrogenation. Various factors that affect catalyst activity, including the reaction temperature, pressure, and space velocity, were investigated. CO2 conversion reached 0.309, and DME and methanol yields were 0.212 and 0.059 with a stoichiometric ratio of H2 to CO2 of 3 at 523 K, 5 MPa, and a space velocity of 6000 mL/(g cat·h). Well-studied kinetic models for methanol synthesis and methanol dehydration, respectively, were used to fit the experimental data and the kinetic parameters in the rate equations for DME synthesis were obtained by regression. A simulated process for CO2 hydrogenation indicated that a higher DME yield can be obtained with CO recycle that will also give a CO-free product. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800777t [article] Dimethyl ether synthesis from CO2 hydrogenation on a CuO-ZnO-Al2O3-ZrO2/HZSM-5 bifunctional catalyst [texte imprimé] / Xin An, Auteur ; Yi-Zan Zuo, Auteur ; Qiang Zhang, Auteur . - 2008 . - p. 6547–6554. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6547–6554 Mots-clés : Dimethy ether synthesis CO2 hydrogenation Bifunctional catalyst Résumé : A CuO−ZnO−Al2O3−ZrO2 + HZSM-5 physical mixture bifunctional catalyst with a high activity for dimethy ether (DME) synthesis was used for CO2 hydrogenation. Various factors that affect catalyst activity, including the reaction temperature, pressure, and space velocity, were investigated. CO2 conversion reached 0.309, and DME and methanol yields were 0.212 and 0.059 with a stoichiometric ratio of H2 to CO2 of 3 at 523 K, 5 MPa, and a space velocity of 6000 mL/(g cat·h). Well-studied kinetic models for methanol synthesis and methanol dehydration, respectively, were used to fit the experimental data and the kinetic parameters in the rate equations for DME synthesis were obtained by regression. A simulated process for CO2 hydrogenation indicated that a higher DME yield can be obtained with CO recycle that will also give a CO-free product. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800777t

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Multiscale model and informatics-based optimal design of experiments / Vinay Prasad in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6555–6567 Titre : Multiscale model and informatics-based optimal design of experiments : application to the catalytic decomposition of ammonia on ruthenium Type de document : texte imprimé Auteurs : Vinay Prasad, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2008 Article en page(s) : p. 6555–6567 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ammonia Multiscale models Complex systems Physics-aided methods Statistics-based Monte Carlo method Résumé : Fundamental multiscale models are increasingly being used to describe complex systems. Microkinetic models, which consider a detailed surface reaction mechanism containing all relevant reactions, are a prototypical multiscale model example. The computational effort in calculating all parameters of a multiscale model for real systems from first principles is prohibitive, and parameter uncertainty still limits full quantitative capabilities of these models. This motivates the development of rational model-based techniques in order to refine uncertain parameters and assess the global (in the entire experimental parameter space) model robustness. Herein we describe physics-aided methods (sensitivity, partial equilibrium, and most abundant reactive intermediate analyses) and statistics-based methods (A, D, and E optimal designs) for the design of experiments. While our methods are fairly general, we demonstrate them for the catalytic decomposition of ammonia on ruthenium to produce hydrogen. A global Monte Carlo method is used to search the operating space to generate possible optimal operating conditions for experiments. Our analysis illustrates that the D optimal and sensitivity-based designs are most promising and generate conditions that delineate important chemistry. It is shown that a standard design around the D optimal point may not be useful for highly nonlinear problems. Instead, informatics methods are proposed to identify optimal regions of the operating space. It is found that the experiments conducted within these regions have a high probability of providing useful kinetics information. It is also shown that the overall direction of the reaction (ammonia decomposition vs synthesis) and the macroenvironment (type of reactor) significantly affect the optimal design. This demonstrates for the first time the effect of macroscopic scales on microscopic ones with important implications for optimal design and product design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800343s [article] Multiscale model and informatics-based optimal design of experiments : application to the catalytic decomposition of ammonia on ruthenium [texte imprimé] / Vinay Prasad, Auteur ; Dionisios G. Vlachos, Auteur . - 2008 . - p. 6555–6567. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6555–6567 Mots-clés : Ammonia Multiscale models Complex systems Physics-aided methods Statistics-based Monte Carlo method Résumé : Fundamental multiscale models are increasingly being used to describe complex systems. Microkinetic models, which consider a detailed surface reaction mechanism containing all relevant reactions, are a prototypical multiscale model example. The computational effort in calculating all parameters of a multiscale model for real systems from first principles is prohibitive, and parameter uncertainty still limits full quantitative capabilities of these models. This motivates the development of rational model-based techniques in order to refine uncertain parameters and assess the global (in the entire experimental parameter space) model robustness. Herein we describe physics-aided methods (sensitivity, partial equilibrium, and most abundant reactive intermediate analyses) and statistics-based methods (A, D, and E optimal designs) for the design of experiments. While our methods are fairly general, we demonstrate them for the catalytic decomposition of ammonia on ruthenium to produce hydrogen. A global Monte Carlo method is used to search the operating space to generate possible optimal operating conditions for experiments. Our analysis illustrates that the D optimal and sensitivity-based designs are most promising and generate conditions that delineate important chemistry. It is shown that a standard design around the D optimal point may not be useful for highly nonlinear problems. Instead, informatics methods are proposed to identify optimal regions of the operating space. It is found that the experiments conducted within these regions have a high probability of providing useful kinetics information. It is also shown that the overall direction of the reaction (ammonia decomposition vs synthesis) and the macroenvironment (type of reactor) significantly affect the optimal design. This demonstrates for the first time the effect of macroscopic scales on microscopic ones with important implications for optimal design and product design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800343s

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Methane conversion to higher hydrocarbons by UV irradiation / Alan R. Derk in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6568–6572 Titre : Methane conversion to higher hydrocarbons by UV irradiation Type de document : texte imprimé Auteurs : Alan R. Derk, Auteur ; Hans H. Funke, Auteur ; Falconer, John L., Auteur Année de publication : 2008 Article en page(s) : p. 6568–6572 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methane conversion UV photolysis Radio-frequency-powered Kr/Ar discharge lamp Résumé : The potential for using UV photolysis to convert methane to higher hydrocarbons with high yields was demonstrated with a radio-frequency- (RF-) powered Kr/Ar discharge lamp (λ = 116.5 and 123.6 nm, flux = 3.3 × 1014 photons/s) at pressures of 47 and 93 kPa and at ambient temperature. The highest conversion was 39%. Photon yields for carbon−carbon bond formation were as high as 4.5. The main reaction products were hydrogen, ethane, propane, and n- and i-butane, but smaller amounts of ethylene and higher alkanes were also detected. The hydrocarbon products followed a Flory distribution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0712840 [article] Methane conversion to higher hydrocarbons by UV irradiation [texte imprimé] / Alan R. Derk, Auteur ; Hans H. Funke, Auteur ; Falconer, John L., Auteur . - 2008 . - p. 6568–6572. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6568–6572 Mots-clés : Methane conversion UV photolysis Radio-frequency-powered Kr/Ar discharge lamp Résumé : The potential for using UV photolysis to convert methane to higher hydrocarbons with high yields was demonstrated with a radio-frequency- (RF-) powered Kr/Ar discharge lamp (λ = 116.5 and 123.6 nm, flux = 3.3 × 1014 photons/s) at pressures of 47 and 93 kPa and at ambient temperature. The highest conversion was 39%. Photon yields for carbon−carbon bond formation were as high as 4.5. The main reaction products were hydrogen, ethane, propane, and n- and i-butane, but smaller amounts of ethylene and higher alkanes were also detected. The hydrocarbon products followed a Flory distribution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0712840

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Influence of structure type of Al2O3 on dehydration of methanol for dimethyl ether synthesis / Chang Won Seo in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6573–6578 Titre : Influence of structure type of Al2O3 on dehydration of methanol for dimethyl ether synthesis Type de document : texte imprimé Auteurs : Chang Won Seo, Auteur ; Kwang Deok Jung, Auteur ; Kwan Young Lee, Auteur Année de publication : 2008 Article en page(s) : p. 6573–6578 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methanol Alumina properties (Y-Al2O3 and n-Al2O3) catalysts Résumé : This study focused on the effect of alumina properties on the catalytic performance in the dehydration of methanol to synthesize dimethyl ether. The catalysts (Y-Al2O3 and n-Al2O3) were prepared from boehmite and bayerite, respectively, via calcination at various temperatures. With heat treatment, the properties of alumina have been changed significantly. Under identical reaction conditions, Y-Al2O3 calcined at 500 °C and n-Al2O3 calcined at 600 °C showed the highest catalytic activity, because of high acid site density among the same types of alumina. Interestingly, n-Al2O3 showed higher catalytic activity than Y-Al2O3, although both catalysts possess comparable acidic properties. This means the structure type of alumina is crucial to determine catalytic performance in this reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800106e [article] Influence of structure type of Al2O3 on dehydration of methanol for dimethyl ether synthesis [texte imprimé] / Chang Won Seo, Auteur ; Kwang Deok Jung, Auteur ; Kwan Young Lee, Auteur . - 2008 . - p. 6573–6578. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6573–6578 Mots-clés : Methanol Alumina properties (Y-Al2O3 and n-Al2O3) catalysts Résumé : This study focused on the effect of alumina properties on the catalytic performance in the dehydration of methanol to synthesize dimethyl ether. The catalysts (Y-Al2O3 and n-Al2O3) were prepared from boehmite and bayerite, respectively, via calcination at various temperatures. With heat treatment, the properties of alumina have been changed significantly. Under identical reaction conditions, Y-Al2O3 calcined at 500 °C and n-Al2O3 calcined at 600 °C showed the highest catalytic activity, because of high acid site density among the same types of alumina. Interestingly, n-Al2O3 showed higher catalytic activity than Y-Al2O3, although both catalysts possess comparable acidic properties. This means the structure type of alumina is crucial to determine catalytic performance in this reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800106e

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Direct partial oxidation of natural gas to liquid chemicals / Christian Lund Rasmussen in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6579–6588 Titre : Direct partial oxidation of natural gas to liquid chemicals : chemical kinetic modeling and global optimization Type de document : texte imprimé Auteurs : Christian Lund Rasmussen, Auteur ; Peter Glarborg, Auteur Année de publication : 2008 Article en page(s) : p. 6579–6588 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methane oxidation Laminar flow quartz reactor Cemical kinetic modeling Résumé : The direct homogeneous partial oxidation of methane to methanol is investigated through modeling and a limited set of experiments. The experiments are conducted in a laminar flow quartz reactor at 100 bar and 598−763 K under undiluted conditions. The modeling is performed with a detailed chemical kinetic model, previously validated against a range of high-pressure data on oxidation of CO/H2 and small hydrocarbons. Modeling predictions compare well also with the experimental data obtained in the present study. On the basis of the chemical kinetic modeling, the effect of the main process parameters is discussed and the process is optimized, using a numerical global optimization methodology based on interval analysis. The experimental data, as well as the optimization results, indicate yields of methanol in the upper range of those reported in literature. However, the values are well below the commercial target. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800137d [article] Direct partial oxidation of natural gas to liquid chemicals : chemical kinetic modeling and global optimization [texte imprimé] / Christian Lund Rasmussen, Auteur ; Peter Glarborg, Auteur . - 2008 . - p. 6579–6588. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6579–6588 Mots-clés : Methane oxidation Laminar flow quartz reactor Cemical kinetic modeling Résumé : The direct homogeneous partial oxidation of methane to methanol is investigated through modeling and a limited set of experiments. The experiments are conducted in a laminar flow quartz reactor at 100 bar and 598−763 K under undiluted conditions. The modeling is performed with a detailed chemical kinetic model, previously validated against a range of high-pressure data on oxidation of CO/H2 and small hydrocarbons. Modeling predictions compare well also with the experimental data obtained in the present study. On the basis of the chemical kinetic modeling, the effect of the main process parameters is discussed and the process is optimized, using a numerical global optimization methodology based on interval analysis. The experimental data, as well as the optimization results, indicate yields of methanol in the upper range of those reported in literature. However, the values are well below the commercial target. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800137d

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Preparation and catalytic evaluation of cobalt-based monolithic and powder catalysts for Fischer-Tropsch synthesis / Robert Guettel in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6589–6597 Titre : Preparation and catalytic evaluation of cobalt-based monolithic and powder catalysts for Fischer-Tropsch synthesis Type de document : texte imprimé Auteurs : Robert Guettel, Auteur ; Jens Knochen, Auteur ; Ulrich Kunz, Auteur Année de publication : 2008 Article en page(s) : p. 6589–6597 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fischer-Tropsch synthesis Cobalt Alumina-supported catalysts Résumé : Cobalt-based monolithic and powder catalysts for Fischer−Tropsch synthesis were prepared. The alumina-supported catalysts contained cobalt (18.6 ± 0.9 wt %) and rhenium (1.2 ± 0.1 wt %) as active phases. To ensure the comparability of both catalysts, monolithic and powder catalysts were prepared from the same CoRe/γ-Al2O3 active powder. While the monolith was prepared by dip coating, the slurry for the coating procedure was also used for preparation of the powder catalyst. It could be shown that both catalysts have comparable composition, pore structure, Brunauer−Emmett−Teller (BET) surface area, and active metal surface area. Catalytic measurements with suspended powder catalyst in a stirred tank reactor and monolithic catalyst in a fixed-bed reactor in the slug-flow regime were performed during Fischer−Tropsch synthesis. Higher reaction rates at comparable methane selectivities were obtained with the monolithic catalyst. Estimations show that the advantageous mass-transfer characteristics of the monolithic catalyst in the slug-flow regime are responsible for this reaction rate enhancement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800377n [article] Preparation and catalytic evaluation of cobalt-based monolithic and powder catalysts for Fischer-Tropsch synthesis [texte imprimé] / Robert Guettel, Auteur ; Jens Knochen, Auteur ; Ulrich Kunz, Auteur . - 2008 . - p. 6589–6597. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6589–6597 Mots-clés : Fischer-Tropsch synthesis Cobalt Alumina-supported catalysts Résumé : Cobalt-based monolithic and powder catalysts for Fischer−Tropsch synthesis were prepared. The alumina-supported catalysts contained cobalt (18.6 ± 0.9 wt %) and rhenium (1.2 ± 0.1 wt %) as active phases. To ensure the comparability of both catalysts, monolithic and powder catalysts were prepared from the same CoRe/γ-Al2O3 active powder. While the monolith was prepared by dip coating, the slurry for the coating procedure was also used for preparation of the powder catalyst. It could be shown that both catalysts have comparable composition, pore structure, Brunauer−Emmett−Teller (BET) surface area, and active metal surface area. Catalytic measurements with suspended powder catalyst in a stirred tank reactor and monolithic catalyst in a fixed-bed reactor in the slug-flow regime were performed during Fischer−Tropsch synthesis. Higher reaction rates at comparable methane selectivities were obtained with the monolithic catalyst. Estimations show that the advantageous mass-transfer characteristics of the monolithic catalyst in the slug-flow regime are responsible for this reaction rate enhancement. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800377n

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Synthesis and characterization of TiO2 coated multiwalled carbon nanotubes using a sol gel method / Sharif Hussein Sharif Zein in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6598–6606 Titre : Synthesis and characterization of TiO2 coated multiwalled carbon nanotubes using a sol gel method Type de document : texte imprimé Auteurs : Sharif Hussein Sharif Zein, Auteur ; Aldo R. Boccaccini, Auteur Année de publication : 2008 Article en page(s) : p. 6598–6606 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : TiO2 coatings Multiwalled carbon nanotubes Sol-gel method Résumé : A considerable improvement in the quality of TiO2 coatings on multiwalled carbon nanotubes (MWNTs) was obtained by introducing a three-step purification and functionalization process which combines oxidation in air followed by sulfuric acid refluxes and reoxidation in air before synthesis of the TiO2 coating by the sol−gel method. A range of techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-rays (EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermal gravimetric analysis (TGA) were applied to characterize TiO2 coated MWNTs obtained by sol−gel. TEM results showed that the MWNTs were fully and homogeneously coated with TiO2 while SEM coupled with EDX confirmed the presence of a thick layer of TiO2 coating the MWNTs. XRD and Raman spectroscopy results revealed that the crystalline structure of TiO2 on the surface of MWNTs was anatase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701770q [article] Synthesis and characterization of TiO2 coated multiwalled carbon nanotubes using a sol gel method [texte imprimé] / Sharif Hussein Sharif Zein, Auteur ; Aldo R. Boccaccini, Auteur . - 2008 . - p. 6598–6606. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6598–6606 Mots-clés : TiO2 coatings Multiwalled carbon nanotubes Sol-gel method Résumé : A considerable improvement in the quality of TiO2 coatings on multiwalled carbon nanotubes (MWNTs) was obtained by introducing a three-step purification and functionalization process which combines oxidation in air followed by sulfuric acid refluxes and reoxidation in air before synthesis of the TiO2 coating by the sol−gel method. A range of techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-rays (EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermal gravimetric analysis (TGA) were applied to characterize TiO2 coated MWNTs obtained by sol−gel. TEM results showed that the MWNTs were fully and homogeneously coated with TiO2 while SEM coupled with EDX confirmed the presence of a thick layer of TiO2 coating the MWNTs. XRD and Raman spectroscopy results revealed that the crystalline structure of TiO2 on the surface of MWNTs was anatase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701770q

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Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors / Hongyun Chen in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6607–6611 Titre : Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors Type de document : texte imprimé Auteurs : Hongyun Chen, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur Année de publication : 2008 Article en page(s) : p. 6607–6611 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mixed metal oxide films Nestlike microstructure LDH film precursors Scanning electron microscopy Résumé : Mixed metal oxide (MMO) films containing Ni2+ and Al3+ have been fabricated by a simple process involving calcination of layered double hydroxide (LDH) film precursors at 300−600 °C for 4 h in air. Scanning electron microscopy (SEM) reveals that the resulting Ni/Al−O thin films maintain the original nestlike morphology of the precursor films without any deformation of the microstructure during the thermal decomposition process. After surface treatment with an aqueous solution of sodium laurate, the wettability of the NiAl-LDH and Ni/Al−O thin film surfaces changes from hydrophilic to hydrophobic. Moreover, whereas the NiAl-LDH film exhibits a low adhesion for water (Cassie−Baxter behavior) after surface modification, the Ni/Al−O films exhibit a high adhesion for water (Wenzel behavior). A possible explanation for this phenomenon has been suggested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800388w [article] Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors [texte imprimé] / Hongyun Chen, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur . - 2008 . - p. 6607–6611. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6607–6611 Mots-clés : Mixed metal oxide films Nestlike microstructure LDH film precursors Scanning electron microscopy Résumé : Mixed metal oxide (MMO) films containing Ni2+ and Al3+ have been fabricated by a simple process involving calcination of layered double hydroxide (LDH) film precursors at 300−600 °C for 4 h in air. Scanning electron microscopy (SEM) reveals that the resulting Ni/Al−O thin films maintain the original nestlike morphology of the precursor films without any deformation of the microstructure during the thermal decomposition process. After surface treatment with an aqueous solution of sodium laurate, the wettability of the NiAl-LDH and Ni/Al−O thin film surfaces changes from hydrophilic to hydrophobic. Moreover, whereas the NiAl-LDH film exhibits a low adhesion for water (Cassie−Baxter behavior) after surface modification, the Ni/Al−O films exhibit a high adhesion for water (Wenzel behavior). A possible explanation for this phenomenon has been suggested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800388w

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Unit operations characterization using historical manufacturing performance / Jerry D. Mitchell in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6612–6621 Titre : Unit operations characterization using historical manufacturing performance Type de document : texte imprimé Auteurs : Jerry D. Mitchell, Auteur ; Kumar Abhinava, Auteur ; Kristi L. Griffiths, Auteur Année de publication : 2008 Article en page(s) : p. 6612–6621 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Unit operations Manufacturing performance Flexibility Résumé : Collecting unit operation performance data on manufacturing processes has many benefits. Besides assessing the health of assets, the data can also be analyzed to drive process improvement activities, to assist in establishing practical operating ranges for new products, and can be used to facilitate process development activities in the laboratory ultimately leading to more robust tech transfers of processes to the manufacturing facility. In this paper, we will describe how to obtain operational variability on the basis of performance data extracted from current and/or historical manufacturing unit operations and its practical uses. Although, the concept was developed initially as a small molecule process design tool, its flexibility is underscored by including an example of how a parenteral manufacturing site used it to identify and correct an issue before it translated into unplanned downtime or product loss. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071256h [article] Unit operations characterization using historical manufacturing performance [texte imprimé] / Jerry D. Mitchell, Auteur ; Kumar Abhinava, Auteur ; Kristi L. Griffiths, Auteur . - 2008 . - p. 6612–6621. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6612–6621 Mots-clés : Unit operations Manufacturing performance Flexibility Résumé : Collecting unit operation performance data on manufacturing processes has many benefits. Besides assessing the health of assets, the data can also be analyzed to drive process improvement activities, to assist in establishing practical operating ranges for new products, and can be used to facilitate process development activities in the laboratory ultimately leading to more robust tech transfers of processes to the manufacturing facility. In this paper, we will describe how to obtain operational variability on the basis of performance data extracted from current and/or historical manufacturing unit operations and its practical uses. Although, the concept was developed initially as a small molecule process design tool, its flexibility is underscored by including an example of how a parenteral manufacturing site used it to identify and correct an issue before it translated into unplanned downtime or product loss. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071256h

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Financial risk management with product pricing in the planning of refinery operations / Hansa Lakkhanawat in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6622–6639 Titre : Financial risk management with product pricing in the planning of refinery operations Type de document : texte imprimé Auteurs : Hansa Lakkhanawat, Auteur ; Miguel J. Bagajewicz, Auteur Année de publication : 2008 Article en page(s) : p. 6622–6639 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Refinery operations Financial risk Résumé : In this paper, the issue of uncertainty and financial risk in refinery operations planning is addressed. The problem is determining how much of each available crude one must purchase and decide on the anticipated production level of different products, given the forecasts of overall demands. We also include, as decision variables, the price of the products. The profit is maximized by taking into account revenues, crude oil costs, inventory costs, and the cost of unsatisfied demand. Data from the refinery that is owned by Bangchak Petroleum Public Company Limited, in Bangkok, Thailand, was used for the example. The results indicate the superiority of the stochastic model, as well as the incorporation of pricing in the decision making over the use of deterministic models. Moreover, we show that, without using pricing, which introduces a price-demand relationship―a feature that normally is not present in existing models―the results that one obtains are overly optimistic, proving that pricing is an essential ingredient of planning. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0710770 [article] Financial risk management with product pricing in the planning of refinery operations [texte imprimé] / Hansa Lakkhanawat, Auteur ; Miguel J. Bagajewicz, Auteur . - 2008 . - p. 6622–6639. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6622–6639 Mots-clés : Refinery operations Financial risk Résumé : In this paper, the issue of uncertainty and financial risk in refinery operations planning is addressed. The problem is determining how much of each available crude one must purchase and decide on the anticipated production level of different products, given the forecasts of overall demands. We also include, as decision variables, the price of the products. The profit is maximized by taking into account revenues, crude oil costs, inventory costs, and the cost of unsatisfied demand. Data from the refinery that is owned by Bangchak Petroleum Public Company Limited, in Bangkok, Thailand, was used for the example. The results indicate the superiority of the stochastic model, as well as the incorporation of pricing in the decision making over the use of deterministic models. Moreover, we show that, without using pricing, which introduces a price-demand relationship―a feature that normally is not present in existing models―the results that one obtains are overly optimistic, proving that pricing is an essential ingredient of planning. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0710770

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Nonparametric identification for control of MIMO hammerstein systems / Jyh-Cheng Jeng in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6640–6647 Titre : Nonparametric identification for control of MIMO hammerstein systems Type de document : texte imprimé Auteurs : Jyh-Cheng Jeng, Auteur ; Hsiao-Ping Huang, Auteur Année de publication : 2008 Article en page(s) : p. 6640–6647 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hammerstein models Nonparametric method Linear dynamic subsystem Algebraic nonlinear function Résumé : A new nonparametric method to identify multivariable Hammerstein models is presented. The Hammerstein model is characterized by a combination of a linear dynamic subsystem and an algebraic nonlinear function. There could be many different models that give the same input−output realization. The purpose of this identification is to find out one among those models for controller design. This identification uses a sequence of specially designed test signals for excitation. The linear dynamic subsystem is identified as a finite sequence of impulse response (FIR), and the static nonlinearity is identified as a multi-input−multi-output (MIMO) functional mapping. By making use of this special test signal, the FIR sequence can be estimated under a single-input−single-output (SISO) framework. Moreover, the identification for linear subsystem can be decoupled from that for the nonlinear static part. This nonparametric model can be used for model predictive control applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071512q [article] Nonparametric identification for control of MIMO hammerstein systems [texte imprimé] / Jyh-Cheng Jeng, Auteur ; Hsiao-Ping Huang, Auteur . - 2008 . - p. 6640–6647. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6640–6647 Mots-clés : Hammerstein models Nonparametric method Linear dynamic subsystem Algebraic nonlinear function Résumé : A new nonparametric method to identify multivariable Hammerstein models is presented. The Hammerstein model is characterized by a combination of a linear dynamic subsystem and an algebraic nonlinear function. There could be many different models that give the same input−output realization. The purpose of this identification is to find out one among those models for controller design. This identification uses a sequence of specially designed test signals for excitation. The linear dynamic subsystem is identified as a finite sequence of impulse response (FIR), and the static nonlinearity is identified as a multi-input−multi-output (MIMO) functional mapping. By making use of this special test signal, the FIR sequence can be estimated under a single-input−single-output (SISO) framework. Moreover, the identification for linear subsystem can be decoupled from that for the nonlinear static part. This nonparametric model can be used for model predictive control applications. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071512q

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Modeling of storage in batching and scheduling of multistage processes / Arul Sundaramoorthy in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6648–6660 Titre : Modeling of storage in batching and scheduling of multistage processes Type de document : texte imprimé Auteurs : Arul Sundaramoorthy, Auteur ; Christos T. Maravelias, Auteur Année de publication : 2008 Article en page(s) : p. 6648–6660 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Multistage processes Storage vessels Batching Scheduling Résumé : The goal of this paper is the development of a mixed-integer programming formulation for the simultaneous batching and scheduling in multiproduct multistage processes with storage constraints. Storage vessels are modeled as additional processing units for which assignment and sequencing constraints are expressed. Our formulation involves selection (batching), assignment and precedence (scheduling) binary variables as well as batch-size and timing continuous variables. We also discuss a general classification of storage policies in multistage processes and show how the proposed formulation can be readily modified to address all classes of problems. Finally, we extend our approach to address problems with sequence-dependent changeovers and stand-alone scheduling problems, and we present a set of tightening constraints that enhance the solution of the proposed models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701737a [article] Modeling of storage in batching and scheduling of multistage processes [texte imprimé] / Arul Sundaramoorthy, Auteur ; Christos T. Maravelias, Auteur . - 2008 . - p. 6648–6660. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6648–6660 Mots-clés : Multistage processes Storage vessels Batching Scheduling Résumé : The goal of this paper is the development of a mixed-integer programming formulation for the simultaneous batching and scheduling in multiproduct multistage processes with storage constraints. Storage vessels are modeled as additional processing units for which assignment and sequencing constraints are expressed. Our formulation involves selection (batching), assignment and precedence (scheduling) binary variables as well as batch-size and timing continuous variables. We also discuss a general classification of storage policies in multistage processes and show how the proposed formulation can be readily modified to address all classes of problems. Finally, we extend our approach to address problems with sequence-dependent changeovers and stand-alone scheduling problems, and we present a set of tightening constraints that enhance the solution of the proposed models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701737a

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Multiobjective optimization in multiechelon decentralized supply chains / T. Sundar Raj in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6661–6671 Titre : Multiobjective optimization in multiechelon decentralized supply chains Type de document : texte imprimé Auteurs : T. Sundar Raj, Auteur ; S. Lakshminarayanan, Auteur Année de publication : 2008 Article en page(s) : p. 6661–6671 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Supply chains Multiobjective fashion optimization Hyper-space diagonal counting method Résumé : Supply chain is a collaborative strategy between raw material vendors, manufacturers, and finished product distributors. It aims for synchronized material, information, and financial flows within the internal components of the supply chain to leverage an effective business outcome. The performance of a supply chain is governed by inventory (resources) minimization and order fill-rate (output) maximization. Any performance improvement in real world supply chains could lead to substantial gain in customer service levels and profit margins, thereby adding to its competitive edge over rival supply chains. This may be achieved by revising the tactical decisions to leverage both internal and external entities of the network and utilizing bullwhip as a beneficial constraint. The present work attempts to improve supply chain performance in a multiobjective fashion using multiobjective optimization. A hyper-space diagonal counting method is employed to process the Pareto front and locate an implementable solution. The workability of this multiobjective performance enhancement approach and the Pareto analysis to identify the right decision are demonstrated using a case study that takes into consideration the different business strategies adopted by supply chains. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800153z [article] Multiobjective optimization in multiechelon decentralized supply chains [texte imprimé] / T. Sundar Raj, Auteur ; S. Lakshminarayanan, Auteur . - 2008 . - p. 6661–6671. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6661–6671 Mots-clés : Supply chains Multiobjective fashion optimization Hyper-space diagonal counting method Résumé : Supply chain is a collaborative strategy between raw material vendors, manufacturers, and finished product distributors. It aims for synchronized material, information, and financial flows within the internal components of the supply chain to leverage an effective business outcome. The performance of a supply chain is governed by inventory (resources) minimization and order fill-rate (output) maximization. Any performance improvement in real world supply chains could lead to substantial gain in customer service levels and profit margins, thereby adding to its competitive edge over rival supply chains. This may be achieved by revising the tactical decisions to leverage both internal and external entities of the network and utilizing bullwhip as a beneficial constraint. The present work attempts to improve supply chain performance in a multiobjective fashion using multiobjective optimization. A hyper-space diagonal counting method is employed to process the Pareto front and locate an implementable solution. The workability of this multiobjective performance enhancement approach and the Pareto analysis to identify the right decision are demonstrated using a case study that takes into consideration the different business strategies adopted by supply chains. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800153z

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Effect of entrainer loss on plant-wide design and control of an isopropanol dehydration process / San-Jang Wang in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6672–6684 Titre : Effect of entrainer loss on plant-wide design and control of an isopropanol dehydration process Type de document : texte imprimé Auteurs : San-Jang Wang, Auteur ; David S. H. Wong, Auteur ; Shuh-Woei Yu, Auteur Année de publication : 2008 Article en page(s) : p. 6672–6684 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Plant-wide design Isopropanol dehydration system Azeotropic distillation Résumé : Azeotropic distillation is an important technology for separating azeotropes or minimizing the energy expenditure of separating close boiling mixtures. In heterogeneous azeotropic distillation, an entrainer is usually added, which is recovered and reused in the subsequent stripping process. Depending on the design, there may be various degrees of entrainer loss. In this work, the plant-wide design and control of an isopropanol dehydration system using cyclohexane as an entrainer via heterogeneous azeotropic distillation is conducted. When there is negligible entrainer loss, a special case of input multiplicity is found, in which a set of design specifications can be achieved by an infinite but bounded set of operating conditions. The optimal condition with the minimum reboiler duty in this bounded set is achieved when the organic recycle flow is the smallest. Due to the existence of these multiple steady states, the entrainer inventory control is self-regulatory over long time operations if a PI control is used for the level of the organic phase in the decanter. If large offsets are allowed in the entrainer inventory control, the system may exhibit a long period of pseudosteady state followed by catastrophic failure. Alternatively, one can allow a small amount of entrainer loss to the bottom of the heterogeneous azeotropic distillation column, and provide a small amount of entrainer makeup. In this case, a control loop is added to guard against process drift due to loss of entrainer. However, because continuous maintenance of entrainer inventory is difficult, an on−off control scheme of entrainer makeup feed is used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002683 [article] Effect of entrainer loss on plant-wide design and control of an isopropanol dehydration process [texte imprimé] / San-Jang Wang, Auteur ; David S. H. Wong, Auteur ; Shuh-Woei Yu, Auteur . - 2008 . - p. 6672–6684. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6672–6684 Mots-clés : Plant-wide design Isopropanol dehydration system Azeotropic distillation Résumé : Azeotropic distillation is an important technology for separating azeotropes or minimizing the energy expenditure of separating close boiling mixtures. In heterogeneous azeotropic distillation, an entrainer is usually added, which is recovered and reused in the subsequent stripping process. Depending on the design, there may be various degrees of entrainer loss. In this work, the plant-wide design and control of an isopropanol dehydration system using cyclohexane as an entrainer via heterogeneous azeotropic distillation is conducted. When there is negligible entrainer loss, a special case of input multiplicity is found, in which a set of design specifications can be achieved by an infinite but bounded set of operating conditions. The optimal condition with the minimum reboiler duty in this bounded set is achieved when the organic recycle flow is the smallest. Due to the existence of these multiple steady states, the entrainer inventory control is self-regulatory over long time operations if a PI control is used for the level of the organic phase in the decanter. If large offsets are allowed in the entrainer inventory control, the system may exhibit a long period of pseudosteady state followed by catastrophic failure. Alternatively, one can allow a small amount of entrainer loss to the bottom of the heterogeneous azeotropic distillation column, and provide a small amount of entrainer makeup. In this case, a control loop is added to guard against process drift due to loss of entrainer. However, because continuous maintenance of entrainer inventory is difficult, an on−off control scheme of entrainer makeup feed is used. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8002683

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Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems / Pietro Altimari in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6685–6697 Titre : Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Costin Sorin Bildea, Auteur Année de publication : 2008 Article en page(s) : p. 6685–6697 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Plug-flow reactor-separation-recycle systems Exothermic reaction Endothermic Résumé : The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071367g [article] Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems [texte imprimé] / Pietro Altimari, Auteur ; Costin Sorin Bildea, Auteur . - 2008 . - p. 6685–6697. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6685–6697 Mots-clés : Plug-flow reactor-separation-recycle systems Exothermic reaction Endothermic Résumé : The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071367g

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Control and monitoring of a high recovery reverse osmosis desalination process / Charles W. McFall in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6698–6710 Titre : Control and monitoring of a high recovery reverse osmosis desalination process Type de document : texte imprimé Auteurs : Charles W. McFall, Auteur ; Alex Bartman, Auteur ; Panagiotis D. Christofides, Auteur Année de publication : 2008 Article en page(s) : p. 6698–6710 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Osmosis desalination process Fault-tolerant contro Fault detection isolation Lyapunov-based control Résumé : Model-based control and monitoring such as feed-forward/feedback control, fault detection and isolation (FDI), and fault-tolerant control (FTC) techniques that utilize Lyapunov-based control laws are implemented on a high recovery reverse osmosis desalination plant model. A detailed mathematical model of a high recovery reverse osmosis plant is developed. This model incorporates the large spatial variations of concentration and flow rate that occur in membrane units during high recovery operation. Bounded nonlinear feedback and feed-forward controllers are developed and applied to this system. The application of these controllers with FDI and FTC is demonstrated in the context of a high recovery reverse osmosis process simulation. The first set of simulations demonstrates the ability to compensate for the effects of large time-varying disturbances in the feed concentration on specific process outputs with and without feed-forward control. The second set of simulations demonstrates the ability of FDI and FTC techniques to recover desired plant operation subject to actuator failures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071559b [article] Control and monitoring of a high recovery reverse osmosis desalination process [texte imprimé] / Charles W. McFall, Auteur ; Alex Bartman, Auteur ; Panagiotis D. Christofides, Auteur . - 2008 . - p. 6698–6710. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6698–6710 Mots-clés : Osmosis desalination process Fault-tolerant contro Fault detection isolation Lyapunov-based control Résumé : Model-based control and monitoring such as feed-forward/feedback control, fault detection and isolation (FDI), and fault-tolerant control (FTC) techniques that utilize Lyapunov-based control laws are implemented on a high recovery reverse osmosis desalination plant model. A detailed mathematical model of a high recovery reverse osmosis plant is developed. This model incorporates the large spatial variations of concentration and flow rate that occur in membrane units during high recovery operation. Bounded nonlinear feedback and feed-forward controllers are developed and applied to this system. The application of these controllers with FDI and FTC is demonstrated in the context of a high recovery reverse osmosis process simulation. The first set of simulations demonstrates the ability to compensate for the effects of large time-varying disturbances in the feed concentration on specific process outputs with and without feed-forward control. The second set of simulations demonstrates the ability of FDI and FTC techniques to recover desired plant operation subject to actuator failures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071559b

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Online fault diagnosis in nonlinear systems using the multiple operating regime approach / Anjali P. Deshpande in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6711–6726 Titre : Online fault diagnosis in nonlinear systems using the multiple operating regime approach Type de document : texte imprimé Auteurs : Anjali P. Deshpande, Auteur ; Sachin C. Patwardhan, Auteur Année de publication : 2008 Article en page(s) : p. 6711–6726 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonlinear systems Multiple-operating-regimes-based technique Bayesian approach Generalized likelihood ratio method Résumé : Many chemical processes exhibit highly nonlinear dynamic behavior when operated over a wide operating range. The fault diagnosis schemes based on a linear perturbation model often prove to be inadequate, with regard to addressing fault diagnosis problems in such systems. In this work, a novel multiple-operating-regimes-based technique is proposed for performing online fault diagnosis in nonlinear systems. A Bayesian approach is used to identify the combination of linear perturbation models in different operating regimes that best-represents the plant dynamics at the current operating point. Nonlinear versions of the generalized likelihood ratio (GLR) method that use multiple linear models for fault identification are proposed. The proposed multimodel based fault diagnosis approaches are computationally efficient and exploit the linearity of each submodel. To arrest the performance degradation caused by the occurrence of faults, the information provided by the fault diagnosis component is then used for online fault accommodation. The efficacy of the proposed diagnosis schemes is demonstrated by conducting simulation studies on two benchmark continuously stirred tank reactor (CSTR) systems and a high-purity binary distillation column system. Analysis of the simulation results reveals that the proposed multimodel Kalman filter-based fault diagnosis schemes outperform the linear GLR method when a nonlinear process is in a transient state over a wide operating range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071593q [article] Online fault diagnosis in nonlinear systems using the multiple operating regime approach [texte imprimé] / Anjali P. Deshpande, Auteur ; Sachin C. Patwardhan, Auteur . - 2008 . - p. 6711–6726. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6711–6726 Mots-clés : Nonlinear systems Multiple-operating-regimes-based technique Bayesian approach Generalized likelihood ratio method Résumé : Many chemical processes exhibit highly nonlinear dynamic behavior when operated over a wide operating range. The fault diagnosis schemes based on a linear perturbation model often prove to be inadequate, with regard to addressing fault diagnosis problems in such systems. In this work, a novel multiple-operating-regimes-based technique is proposed for performing online fault diagnosis in nonlinear systems. A Bayesian approach is used to identify the combination of linear perturbation models in different operating regimes that best-represents the plant dynamics at the current operating point. Nonlinear versions of the generalized likelihood ratio (GLR) method that use multiple linear models for fault identification are proposed. The proposed multimodel based fault diagnosis approaches are computationally efficient and exploit the linearity of each submodel. To arrest the performance degradation caused by the occurrence of faults, the information provided by the fault diagnosis component is then used for online fault accommodation. The efficacy of the proposed diagnosis schemes is demonstrated by conducting simulation studies on two benchmark continuously stirred tank reactor (CSTR) systems and a high-purity binary distillation column system. Analysis of the simulation results reveals that the proposed multimodel Kalman filter-based fault diagnosis schemes outperform the linear GLR method when a nonlinear process is in a transient state over a wide operating range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071593q

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Kinetics of cholesterol extraction using supercritical carbon dioxide with cosolvents / N. Vedaraman in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6727–6733 Titre : Kinetics of cholesterol extraction using supercritical carbon dioxide with cosolvents Type de document : texte imprimé Auteurs : N. Vedaraman, Auteur ; C. Srinivasakannan, Auteur ; G. Brunner, Auteur Année de publication : 2008 Article en page(s) : p. 6727–6733 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cholesterol Carbon dioxide Cosolvents Résumé : Cattle brain is rich in lipids including cholesterol. As a alternative process to extract cholesterol, the ecofriendly solvent supercritical carbon dioxide (SC CO2), along with different cosolvents such as acetone, 2-propanol, and ethanol, was used in an attempt to understand the effect of cosolvents. A maximum of 53% of the total cholesterol in the brain sample could only be extracted either using pure SC CO2 or using cosolvents along with SC CO2. Although the total amount of cholesterol extracted did not differ with the addition of cosolvents, the rate of extraction was found to increase significantly with the addition of cosolvents in small quantities. The kinetics of extraction using pure SC CO2 as well SC CO2 with cosolvents was modeled using conventional differential mass balance equation for packed beds. The effective diffusivity coefficient was found to double with cosolvent acetone, while found to be more than three times with cosolvents 2-propanol and ethanol in comparison with the pure SC CO2. The effective diffusivity coefficient was found to be of the order of 10−13 m2/s, for extraction of cholesterol from cattle brain, either with SC CO2 or SC CO2 with cosolvents. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070703q [article] Kinetics of cholesterol extraction using supercritical carbon dioxide with cosolvents [texte imprimé] / N. Vedaraman, Auteur ; C. Srinivasakannan, Auteur ; G. Brunner, Auteur . - 2008 . - p. 6727–6733. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6727–6733 Mots-clés : Cholesterol Carbon dioxide Cosolvents Résumé : Cattle brain is rich in lipids including cholesterol. As a alternative process to extract cholesterol, the ecofriendly solvent supercritical carbon dioxide (SC CO2), along with different cosolvents such as acetone, 2-propanol, and ethanol, was used in an attempt to understand the effect of cosolvents. A maximum of 53% of the total cholesterol in the brain sample could only be extracted either using pure SC CO2 or using cosolvents along with SC CO2. Although the total amount of cholesterol extracted did not differ with the addition of cosolvents, the rate of extraction was found to increase significantly with the addition of cosolvents in small quantities. The kinetics of extraction using pure SC CO2 as well SC CO2 with cosolvents was modeled using conventional differential mass balance equation for packed beds. The effective diffusivity coefficient was found to double with cosolvent acetone, while found to be more than three times with cosolvents 2-propanol and ethanol in comparison with the pure SC CO2. The effective diffusivity coefficient was found to be of the order of 10−13 m2/s, for extraction of cholesterol from cattle brain, either with SC CO2 or SC CO2 with cosolvents. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie070703q

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Effect of electrochemical reduction and oxidation of a viscose rayon based activated carbon cloth for Cr(VI) sorption from aqueous solution / Ibiba D. Harry in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6734–6741 Titre : Effect of electrochemical reduction and oxidation of a viscose rayon based activated carbon cloth for Cr(VI) sorption from aqueous solution Type de document : texte imprimé Auteurs : Ibiba D. Harry, Auteur ; Basu Saha, Auteur ; Iain W. Cumming, Auteur Année de publication : 2008 Article en page(s) : p. 6734–6741 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Viscose rayon Activated carbon cloth Sorption experiments Résumé : A viscose rayon based activated carbon cloth (ACC) was electrochemically reduced and oxidized to enhance its anion and cation sorption capacity for comparison with the as-received ACC. ACCs were characterized by chloride capacity measurement, sodium capacity measurement, pH titration, elemental analysis, Brunauer−Emmet−Teller surface area measurement, Fourier transform infrared spectroscopy analysis and scanning electron microscopy. Batch sorption experiments showed that chromium(VI) sorption capacity of electrochemically reduced ACC increased 2.12 times at solution pH 4 and chromium(VI) sorption capacity for electrochemically oxidized ACC increased 11.35 times at solution pH 8. The highest chromium(VI) sorption capacity was obtained on electrochemically reduced ACC at solution pH 4 (i.e., 3.8 mmol/g). Chromium(VI) sorption decreased with an increase in solution pH for electrochemically reduced ACC, while it increased with an increase in solution pH for electrochemically oxidized ACC. Chromium(VI) ions were sorbed onto ACCs by ion exchange. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0711933 [article] Effect of electrochemical reduction and oxidation of a viscose rayon based activated carbon cloth for Cr(VI) sorption from aqueous solution [texte imprimé] / Ibiba D. Harry, Auteur ; Basu Saha, Auteur ; Iain W. Cumming, Auteur . - 2008 . - p. 6734–6741. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6734–6741 Mots-clés : Viscose rayon Activated carbon cloth Sorption experiments Résumé : A viscose rayon based activated carbon cloth (ACC) was electrochemically reduced and oxidized to enhance its anion and cation sorption capacity for comparison with the as-received ACC. ACCs were characterized by chloride capacity measurement, sodium capacity measurement, pH titration, elemental analysis, Brunauer−Emmet−Teller surface area measurement, Fourier transform infrared spectroscopy analysis and scanning electron microscopy. Batch sorption experiments showed that chromium(VI) sorption capacity of electrochemically reduced ACC increased 2.12 times at solution pH 4 and chromium(VI) sorption capacity for electrochemically oxidized ACC increased 11.35 times at solution pH 8. The highest chromium(VI) sorption capacity was obtained on electrochemically reduced ACC at solution pH 4 (i.e., 3.8 mmol/g). Chromium(VI) sorption decreased with an increase in solution pH for electrochemically reduced ACC, while it increased with an increase in solution pH for electrochemically oxidized ACC. Chromium(VI) ions were sorbed onto ACCs by ion exchange. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0711933

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Comparison of the batch and breakthrough properties of stable and plain alginate microcapsules with a chelating resin and an ion exchanger in Ag+adsorption / Mohammad Outokesh in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6742–6752 Titre : Comparison of the batch and breakthrough properties of stable and plain alginate microcapsules with a chelating resin and an ion exchanger in Ag+adsorption Type de document : texte imprimé Auteurs : Mohammad Outokesh, Auteur ; Yuichi Niibori, Auteur ; Hitoshi Mimura, Auteur Année de publication : 2008 Article en page(s) : p. 6742–6752 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Alginate microcapsules Ag+ adsorption Ion exchanger Résumé : A comparative study on the uptake properties of alginate microcapsules containing Cyanex 302 extractant, Lewatite TP 214 chelating resin, and Amberlite 200CT strongly acidic ion exchanger has been conducted using Ag+ as the target ion. The study resulted in an analytical formula, as well as three phenomenological breakthrough formulas that are also applicable in other fixed-bed operations. It also demonstrated a close similarity of the uptake properties of alginate microcapsules (MCs) and the chelating resins. Advantages of MCs over chelating resins include ease of preparation, ability to immobilize different extractants, and, most remarkably, an enormous distribution factor (Kd ≈ 106 cm3/g). As for the stabilization of MCs, two different methods of coating and matrix modification were applied; the latter proved to be superior, because of enhancement of both the uptake capacity and the column performance. Another achievement of the current study was the discovery of a new method for estimating the thickness of the coating layer of MCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071200n [article] Comparison of the batch and breakthrough properties of stable and plain alginate microcapsules with a chelating resin and an ion exchanger in Ag+adsorption [texte imprimé] / Mohammad Outokesh, Auteur ; Yuichi Niibori, Auteur ; Hitoshi Mimura, Auteur . - 2008 . - p. 6742–6752. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6742–6752 Mots-clés : Alginate microcapsules Ag+ adsorption Ion exchanger Résumé : A comparative study on the uptake properties of alginate microcapsules containing Cyanex 302 extractant, Lewatite TP 214 chelating resin, and Amberlite 200CT strongly acidic ion exchanger has been conducted using Ag+ as the target ion. The study resulted in an analytical formula, as well as three phenomenological breakthrough formulas that are also applicable in other fixed-bed operations. It also demonstrated a close similarity of the uptake properties of alginate microcapsules (MCs) and the chelating resins. Advantages of MCs over chelating resins include ease of preparation, ability to immobilize different extractants, and, most remarkably, an enormous distribution factor (Kd ≈ 106 cm3/g). As for the stabilization of MCs, two different methods of coating and matrix modification were applied; the latter proved to be superior, because of enhancement of both the uptake capacity and the column performance. Another achievement of the current study was the discovery of a new method for estimating the thickness of the coating layer of MCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071200n

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Chromatographic separations of traces 134Cs, 60Co, and 152,154Eu using silico-, molybdo-, and chromotitanates as inorganic ion exchangers / Mamdouh M. Abou-Mesalam in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6753–6758 Titre : Chromatographic separations of traces 134Cs, 60Co, and 152,154Eu using silico-, molybdo-, and chromotitanates as inorganic ion exchangers Type de document : texte imprimé Auteurs : Mamdouh M. Abou-Mesalam, Auteur ; Ibrahim M. El-Naggar, Auteur Année de publication : 2008 Article en page(s) : p. 6753–6758 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : 134Cs 60Co 152,154Eu Silicotitanate Molybdotitanate Chromotitanate Batch adsorption technique Résumé : Silicotitanate, molybdotitanate, and chromotitanate as inorganic ion exchange materials were synthesized with Si/Ti, Mo/Ti, and Cr/Ti ratios equal to 1.0, 1.33, and 0.5, respectively. The chemical composition of the synthesized materials were determined and found to SiTiO4·9.52H2O, Mo4Ti3O16·10.2H2O, and Cr2Ti4O11·5.65H2O for silicotitanate, molybdotitanate, and chromotitanate, respectively. Schematic illustrations of these materials were achieved according to the related structures. The stability of these synthesized materials in different media showed high resistance toward chemical attack. Batch adsorption technique was used for the investigation of the distribution coefficients of 134Cs, 60Co, and 152,154Eu from synthetic mixture solutions on the three inorganic ion exchangers. The effect of the medium composition (pH) on the distribution coefficients was studied, and the data obtained indicated that 60Co had a very low distribution coefficient on the three ion exchangers in 0.1 M HNO3 and a mixed system of 0.1 M HNO3 + 0.1 M NaNO3. 134Cs and 152,154Eu are highly adsorbed on molybdotitanate and chromotitanate in 0.1 M HNO3 medium; on the other hand, these ions have high distribution coefficients on silicotitanate in 0.1 M HNO3 + 0.1 M NaNO3 medium. Based on the batch distribution coefficient data achieved, chromatographic column separations of 134Cs−60Co, 134Cs−152,154Eu, and 60Co−152,154Eu were carried out using different eluants such as 0.01 M HNO3, 0.1 M HNO3, 0.1 M NH4Cl, and 0.1 M NH4OH. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071341p [article] Chromatographic separations of traces 134Cs, 60Co, and 152,154Eu using silico-, molybdo-, and chromotitanates as inorganic ion exchangers [texte imprimé] / Mamdouh M. Abou-Mesalam, Auteur ; Ibrahim M. El-Naggar, Auteur . - 2008 . - p. 6753–6758. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6753–6758 Mots-clés : 134Cs 60Co 152,154Eu Silicotitanate Molybdotitanate Chromotitanate Batch adsorption technique Résumé : Silicotitanate, molybdotitanate, and chromotitanate as inorganic ion exchange materials were synthesized with Si/Ti, Mo/Ti, and Cr/Ti ratios equal to 1.0, 1.33, and 0.5, respectively. The chemical composition of the synthesized materials were determined and found to SiTiO4·9.52H2O, Mo4Ti3O16·10.2H2O, and Cr2Ti4O11·5.65H2O for silicotitanate, molybdotitanate, and chromotitanate, respectively. Schematic illustrations of these materials were achieved according to the related structures. The stability of these synthesized materials in different media showed high resistance toward chemical attack. Batch adsorption technique was used for the investigation of the distribution coefficients of 134Cs, 60Co, and 152,154Eu from synthetic mixture solutions on the three inorganic ion exchangers. The effect of the medium composition (pH) on the distribution coefficients was studied, and the data obtained indicated that 60Co had a very low distribution coefficient on the three ion exchangers in 0.1 M HNO3 and a mixed system of 0.1 M HNO3 + 0.1 M NaNO3. 134Cs and 152,154Eu are highly adsorbed on molybdotitanate and chromotitanate in 0.1 M HNO3 medium; on the other hand, these ions have high distribution coefficients on silicotitanate in 0.1 M HNO3 + 0.1 M NaNO3 medium. Based on the batch distribution coefficient data achieved, chromatographic column separations of 134Cs−60Co, 134Cs−152,154Eu, and 60Co−152,154Eu were carried out using different eluants such as 0.01 M HNO3, 0.1 M HNO3, 0.1 M NH4Cl, and 0.1 M NH4OH. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071341p

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Effect of reaction temperature on the performance of thermal swing sorption-enhanced reaction process for simultaneous production of fuel-cell-grade H2 and compressed CO2 from synthesis gas / Ki Bong Lee in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6759–6764 Titre : Effect of reaction temperature on the performance of thermal swing sorption-enhanced reaction process for simultaneous production of fuel-cell-grade H2 and compressed CO2 from synthesis gas Type de document : texte imprimé Auteurs : Ki Bong Lee, Auteur ; Michael G. Beaver, Auteur ; Hugo. S. Caram, Auteur Année de publication : 2008 Article en page(s) : p. 6759–6764 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : TSSER process Fuel-cell-grade H2 Compressed CO2 WGS catalyst Résumé : A novel cyclic thermal swing sorption-enhanced reaction (TSSER) process concept was recently proposed for the simultaneous production of fuel-cell-grade H2 and compressed CO2 from synthesis gas containing CO and H2O. The process carried out the catalytic water−gas shift (WGS) reaction (CO + H2O ↔ CO2 + H2) with simultaneous removal of CO2 from the reaction zone by a reversible, water-tolerant, CO2-selective chemisorbent in order to circumvent the thermodynamic limitation of the WGS reaction and enhance the rate of the forward reaction. The chemisorbent was periodically regenerated using the principles of thermal swing adsorption by purging the sorber−reactor with superheated steam at different pressures and temperatures. Several intermediate process steps were employed to produce a pure and compressed CO2 byproduct during the thermal desorption process. The present work reports (a) new experimental data demonstrating the concept of the sorption-enhanced WGS reaction at different temperatures using a commercial WGS catalyst and Na2O-promoted alumina as the CO2 chemisorbent and (b) the effect of the sorption−reaction temperature on the TSSER process performance estimated by model simulation. Relatively slower kinetics of the sorption-enhanced WGS reaction imposes a lower bound (∼200 °C), whereas the thermal stability of the chemisorbent and the use of carbon steel sorber−reactors set the upper bound (∼550 °C) of temperatures for practical operation of the TSSER process. Simulated process performances (sorption−reaction at 200 and 400 °C and regeneration at 550 °C) show that the operation of the sorption−reaction step at 200 °C increases the H2 and CO2 productivities of the process by ∼38% and 35%, respectively, without changing (a) the number of moles of H2 produced per mole of CO in the feed gas or (b) the net CO2 recovery as a compressed byproduct gas. The total steam duty for the sorbent regeneration increases by ∼14% for operation at the lower sorption−reaction temperature. Another major benefit of operation at the lower reaction temperature is a very large increase in the pressure of the CO2 byproduct (e.g., 40 and 21 atm at 200 and 400 °C, respectively) when the reactor feed gas contained 20% CO + 80% H2O at a total pressure of 15 atm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071372k [article] Effect of reaction temperature on the performance of thermal swing sorption-enhanced reaction process for simultaneous production of fuel-cell-grade H2 and compressed CO2 from synthesis gas [texte imprimé] / Ki Bong Lee, Auteur ; Michael G. Beaver, Auteur ; Hugo. S. Caram, Auteur . - 2008 . - p. 6759–6764. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6759–6764 Mots-clés : TSSER process Fuel-cell-grade H2 Compressed CO2 WGS catalyst Résumé : A novel cyclic thermal swing sorption-enhanced reaction (TSSER) process concept was recently proposed for the simultaneous production of fuel-cell-grade H2 and compressed CO2 from synthesis gas containing CO and H2O. The process carried out the catalytic water−gas shift (WGS) reaction (CO + H2O ↔ CO2 + H2) with simultaneous removal of CO2 from the reaction zone by a reversible, water-tolerant, CO2-selective chemisorbent in order to circumvent the thermodynamic limitation of the WGS reaction and enhance the rate of the forward reaction. The chemisorbent was periodically regenerated using the principles of thermal swing adsorption by purging the sorber−reactor with superheated steam at different pressures and temperatures. Several intermediate process steps were employed to produce a pure and compressed CO2 byproduct during the thermal desorption process. The present work reports (a) new experimental data demonstrating the concept of the sorption-enhanced WGS reaction at different temperatures using a commercial WGS catalyst and Na2O-promoted alumina as the CO2 chemisorbent and (b) the effect of the sorption−reaction temperature on the TSSER process performance estimated by model simulation. Relatively slower kinetics of the sorption-enhanced WGS reaction imposes a lower bound (∼200 °C), whereas the thermal stability of the chemisorbent and the use of carbon steel sorber−reactors set the upper bound (∼550 °C) of temperatures for practical operation of the TSSER process. Simulated process performances (sorption−reaction at 200 and 400 °C and regeneration at 550 °C) show that the operation of the sorption−reaction step at 200 °C increases the H2 and CO2 productivities of the process by ∼38% and 35%, respectively, without changing (a) the number of moles of H2 produced per mole of CO in the feed gas or (b) the net CO2 recovery as a compressed byproduct gas. The total steam duty for the sorbent regeneration increases by ∼14% for operation at the lower sorption−reaction temperature. Another major benefit of operation at the lower reaction temperature is a very large increase in the pressure of the CO2 byproduct (e.g., 40 and 21 atm at 200 and 400 °C, respectively) when the reactor feed gas contained 20% CO + 80% H2O at a total pressure of 15 atm. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071372k

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Polymer structure and metal ion selectivity in silica polyamine composites modified with sodium chloroacetate and nitriloacetic acid (NTA) anhydride / Mark A. Hughes in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6765–6774 Titre : Polymer structure and metal ion selectivity in silica polyamine composites modified with sodium chloroacetate and nitriloacetic acid (NTA) anhydride Type de document : texte imprimé Auteurs : Mark A. Hughes, Auteur ; Jessica Wood, Auteur ; Edward Rosenberg, Auteur Année de publication : 2008 Article en page(s) : p. 6765–6774 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Silica polyamine composite Amine ligands Résumé : Previously, silica polyamine composite (SPC) materials (BP-1 and WP-1) containing amine chelating groups were prepared using two polyamines, polyallylamine (PAA), and polyethyleneimine (PEI). In this paper the amine ligands of BP-1 and WP-1 were modified with chloroacetate, yielding the new SPC materials BP-2 and WP-2. We have found that the acetate groups were bound to the amine groups to a greater extent on the SPC prepared using PAA (BP-1) relative to the SPC prepared with PEI (WP-1). BP-2 was selective for Cu2+ over other divalent metal ions from polymetallic solutions in the pH range of 1 to 3. In contrast, WP-2 was selective for Cu2+ over other divalent metal ions at pH 1 only and coloaded significant amounts of Ni2+ at pH 2 and pH 3. Thus, polyamine structure impacts the metal selectivity of the resultant SPC materials, BP-2 and WP-2. Two novel SPCs were prepared from nitriloacetic acid (NTA) anhydride using BP-1 and WP-1, yielding BP-NT and WP-NT, respectively. The resultant materials possess a unique chelating ligand, in which an iminodiacetic acid (IDA) group is covalently bonded to the SPC amine groups via an amide bond. The two materials (BP-NT, WP-NT) have similar metal selectivity profiles indicating that polyamine structure is not influential. Increased ligand denticity and the amide linker prevent the polymer from playing a large role in selectivity. The resulting materials have the ability to remove divalent and trivalent metal ions from low pH aqueous solutions. These materials can be regenerated by treatment with acid solution and showed no evidence of amide bond hydrolysis under acidic conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800359k [article] Polymer structure and metal ion selectivity in silica polyamine composites modified with sodium chloroacetate and nitriloacetic acid (NTA) anhydride [texte imprimé] / Mark A. Hughes, Auteur ; Jessica Wood, Auteur ; Edward Rosenberg, Auteur . - 2008 . - p. 6765–6774. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6765–6774 Mots-clés : Silica polyamine composite Amine ligands Résumé : Previously, silica polyamine composite (SPC) materials (BP-1 and WP-1) containing amine chelating groups were prepared using two polyamines, polyallylamine (PAA), and polyethyleneimine (PEI). In this paper the amine ligands of BP-1 and WP-1 were modified with chloroacetate, yielding the new SPC materials BP-2 and WP-2. We have found that the acetate groups were bound to the amine groups to a greater extent on the SPC prepared using PAA (BP-1) relative to the SPC prepared with PEI (WP-1). BP-2 was selective for Cu2+ over other divalent metal ions from polymetallic solutions in the pH range of 1 to 3. In contrast, WP-2 was selective for Cu2+ over other divalent metal ions at pH 1 only and coloaded significant amounts of Ni2+ at pH 2 and pH 3. Thus, polyamine structure impacts the metal selectivity of the resultant SPC materials, BP-2 and WP-2. Two novel SPCs were prepared from nitriloacetic acid (NTA) anhydride using BP-1 and WP-1, yielding BP-NT and WP-NT, respectively. The resultant materials possess a unique chelating ligand, in which an iminodiacetic acid (IDA) group is covalently bonded to the SPC amine groups via an amide bond. The two materials (BP-NT, WP-NT) have similar metal selectivity profiles indicating that polyamine structure is not influential. Increased ligand denticity and the amide linker prevent the polymer from playing a large role in selectivity. The resulting materials have the ability to remove divalent and trivalent metal ions from low pH aqueous solutions. These materials can be regenerated by treatment with acid solution and showed no evidence of amide bond hydrolysis under acidic conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800359k

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Theoretical and experimental analysis of the role of sludge age on the removal of adsorbed micropollutants in activated sludge processes / Davide Dionisi in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6775–6782 Titre : Theoretical and experimental analysis of the role of sludge age on the removal of adsorbed micropollutants in activated sludge processes Type de document : texte imprimé Auteurs : Davide Dionisi, Auteur ; Lorena Bornoroni, Auteur ; Sara Mainelli, Auteur Année de publication : 2008 Article en page(s) : p. 6775–6782 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sludge age Micropollutants Liquid-phase concentrations Solid-phase Résumé : This paper analyses how sludge age, the most important design parameter for activated sludge processes, affects effluent concentrations of those micropollutants which are removable only by adsorption on activated sludge flocs. A mathematical model has been developed for sequencing batch reactors (SBRs) treating readily biodegradable substrates and micropollutants, in order to calculate the effect of sludge age on liquid- and solid-phase concentrations of micropollutants, both during the startup and at steady state. It was shown that the increase in sludge age, at fixed values of the other parameters, causes an increase of the concentration of micropollutants both in the liquid and in the solid phase. At any given sludge age, the effect of process parameters (e.g., biomass kinetic and stoichiometric parameters, influent concentration of readily biodegradable substrate) on the removal of the micropollutant was discussed. Experimental data were collected from two parallel laboratory-scale SBRs operated under identical conditions and feed composition, the only difference being sludge age (4 vs 26 days). Removal of cadmium and lead in the two reactors was compared. Effluent cadmium concentration was significantly higher at higher sludge age (25% of the influent concentration vs 12% at the lower sludge age). Lead removal, on the ther hand, was not significantly affected by sludge age and other removal mechanisms, as precipitation, likely occurred. Other literature data on removal of micropollutants in activated sludge processes were critically analyzed in light of the findings obtained in this study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071280v [article] Theoretical and experimental analysis of the role of sludge age on the removal of adsorbed micropollutants in activated sludge processes [texte imprimé] / Davide Dionisi, Auteur ; Lorena Bornoroni, Auteur ; Sara Mainelli, Auteur . - 2008 . - p. 6775–6782. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6775–6782 Mots-clés : Sludge age Micropollutants Liquid-phase concentrations Solid-phase Résumé : This paper analyses how sludge age, the most important design parameter for activated sludge processes, affects effluent concentrations of those micropollutants which are removable only by adsorption on activated sludge flocs. A mathematical model has been developed for sequencing batch reactors (SBRs) treating readily biodegradable substrates and micropollutants, in order to calculate the effect of sludge age on liquid- and solid-phase concentrations of micropollutants, both during the startup and at steady state. It was shown that the increase in sludge age, at fixed values of the other parameters, causes an increase of the concentration of micropollutants both in the liquid and in the solid phase. At any given sludge age, the effect of process parameters (e.g., biomass kinetic and stoichiometric parameters, influent concentration of readily biodegradable substrate) on the removal of the micropollutant was discussed. Experimental data were collected from two parallel laboratory-scale SBRs operated under identical conditions and feed composition, the only difference being sludge age (4 vs 26 days). Removal of cadmium and lead in the two reactors was compared. Effluent cadmium concentration was significantly higher at higher sludge age (25% of the influent concentration vs 12% at the lower sludge age). Lead removal, on the ther hand, was not significantly affected by sludge age and other removal mechanisms, as precipitation, likely occurred. Other literature data on removal of micropollutants in activated sludge processes were critically analyzed in light of the findings obtained in this study. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071280v

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Diffusion coefficients of n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1phenyloctane, and 1-phenyldodecane in supercritical carbon dioxide / Consuelo Pizarro in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6783–6789 Titre : Diffusion coefficients of n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1phenyloctane, and 1-phenyldodecane in supercritical carbon dioxide Type de document : texte imprimé Auteurs : Consuelo Pizarro, Auteur ; Octavio Suárez-Iglesias, Auteur ; Ignacio Medina, Auteur Année de publication : 2008 Article en page(s) : p. 6783–6789 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : n-alkylbenzenes Diffusion coefficients Taylor-Aris technique Résumé : Binary diffusion coefficients at infinite dilution in supercritical carbon dioxide, DAB, were measured for five n-alkylbenzenes (n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1-phenyloctane, and 1-phenyldodecane) by means of the Taylor−Aris technique in a chromatographic apparatus from 313 to 333 K and from 15.0 to 35.0 MPa. The experimental results were correlated with temperature, pressure, solvent viscosity, and solvent density. In the case of temperature dependence, additional measurements were carried out for n-pentylbenzene from 308 to 398 K at 35.0 MPa. As the five solutes are similar molecules, the corresponding states principle of Teja was tested together with the results obtained from several predictive equations based on the Stokes−Einstein formula and on the rough-hard-sphere model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071538h [article] Diffusion coefficients of n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1phenyloctane, and 1-phenyldodecane in supercritical carbon dioxide [texte imprimé] / Consuelo Pizarro, Auteur ; Octavio Suárez-Iglesias, Auteur ; Ignacio Medina, Auteur . - 2008 . - p. 6783–6789. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6783–6789 Mots-clés : n-alkylbenzenes Diffusion coefficients Taylor-Aris technique Résumé : Binary diffusion coefficients at infinite dilution in supercritical carbon dioxide, DAB, were measured for five n-alkylbenzenes (n-butylbenzene, n-pentylbenzene, 1-phenylhexane, 1-phenyloctane, and 1-phenyldodecane) by means of the Taylor−Aris technique in a chromatographic apparatus from 313 to 333 K and from 15.0 to 35.0 MPa. The experimental results were correlated with temperature, pressure, solvent viscosity, and solvent density. In the case of temperature dependence, additional measurements were carried out for n-pentylbenzene from 308 to 398 K at 35.0 MPa. As the five solutes are similar molecules, the corresponding states principle of Teja was tested together with the results obtained from several predictive equations based on the Stokes−Einstein formula and on the rough-hard-sphere model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071538h

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Transferred arc production of fumed silica / Ramona Pristavita in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6790–6795 Titre : Transferred arc production of fumed silica : rheological properties Type de document : texte imprimé Auteurs : Ramona Pristavita, Auteur ; Richard J. Munz, Auteur ; Tony Addona, Auteur Année de publication : 2008 Article en page(s) : p. 6790–6795 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fumed silica Rheological properties Résumé : Different grades of fumed silica can be obtained using an environmentally friendly thermal plasma process. In the present work, we studied the changes in the powder quality by varying the quench conditions used for the production of the powder and by agglomerating the product. Tests done before and after the agglomeration experiments showed that the agglomeration had no effect on the powder’s rheological or other properties. We concluded that the inferior rheological properties of the plasma produced fumed silica were due to the lack of the free hydroxyl groups on the surface of the particles. Posttreatment of plasma produced powder showed that the surface chemistry was modified and the free hydroxyl groups were introduced on the surface of the particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701724s [article] Transferred arc production of fumed silica : rheological properties [texte imprimé] / Ramona Pristavita, Auteur ; Richard J. Munz, Auteur ; Tony Addona, Auteur . - 2008 . - p. 6790–6795. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6790–6795 Mots-clés : Fumed silica Rheological properties Résumé : Different grades of fumed silica can be obtained using an environmentally friendly thermal plasma process. In the present work, we studied the changes in the powder quality by varying the quench conditions used for the production of the powder and by agglomerating the product. Tests done before and after the agglomeration experiments showed that the agglomeration had no effect on the powder’s rheological or other properties. We concluded that the inferior rheological properties of the plasma produced fumed silica were due to the lack of the free hydroxyl groups on the surface of the particles. Posttreatment of plasma produced powder showed that the surface chemistry was modified and the free hydroxyl groups were introduced on the surface of the particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701724s

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Influence of compressed carbon dioxide on hydrogenation reactions in cyclohexane with a Pd/C catalyst / Jianmin Hao in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6796–6800 Titre : Influence of compressed carbon dioxide on hydrogenation reactions in cyclohexane with a Pd/C catalyst Type de document : texte imprimé Auteurs : Jianmin Hao, Auteur ; Chunyu Xi, Auteur ; Haiyang Cheng, Auteur Année de publication : 2008 Article en page(s) : p. 6796–6800 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2--Hydrogenation Pd/C Catalyst Résumé : The potential of CO2-expanded liquid media for chemical reactions has been examined in this work, using cyclohexane as a solvent and Pd/C as a heterogeneous catalyst for hydrogenation of styrene, citral, and nitrobenzene with H2. The rate of hydrogenation reactions is increased, and the product selectivity is altered in the CO2-expanded cyclohexane phase.In the hydrogenation of citral, the selectivity to citronellal decreases with CO2 pressure, which changes from ~80% in the neat cyclohexane to ~65% at 16 MPa. The CO2 dissolved in the cyclohexane phase may accelerate the rate of further hydrogenation of citronellal. In the hydrogenation of nitrobenzene, the selectivity to aniline is large >90% in the absence of dense phase CO2 but it increases up to >95% on CO2 pressurization of the liquid reaction phase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071453g [article] Influence of compressed carbon dioxide on hydrogenation reactions in cyclohexane with a Pd/C catalyst [texte imprimé] / Jianmin Hao, Auteur ; Chunyu Xi, Auteur ; Haiyang Cheng, Auteur . - 2008 . - p. 6796–6800. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6796–6800 Mots-clés : CO2--Hydrogenation Pd/C Catalyst Résumé : The potential of CO2-expanded liquid media for chemical reactions has been examined in this work, using cyclohexane as a solvent and Pd/C as a heterogeneous catalyst for hydrogenation of styrene, citral, and nitrobenzene with H2. The rate of hydrogenation reactions is increased, and the product selectivity is altered in the CO2-expanded cyclohexane phase.In the hydrogenation of citral, the selectivity to citronellal decreases with CO2 pressure, which changes from ~80% in the neat cyclohexane to ~65% at 16 MPa. The CO2 dissolved in the cyclohexane phase may accelerate the rate of further hydrogenation of citronellal. In the hydrogenation of nitrobenzene, the selectivity to aniline is large >90% in the absence of dense phase CO2 but it increases up to >95% on CO2 pressurization of the liquid reaction phase. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071453g

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