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Vol. 51 N° 20 - Mai 2012 [texte imprimé] . - 2012 . - p. 6991-7136 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierExtraction of Polyphenolic Compounds from Eucalyptus globulus Bark / Inês Mota in Industrial & engineering chemistry research, Vol. 51 N° 20 (Mai 2012)
Titre : Extraction of Polyphenolic Compounds from Eucalyptus globulus Bark : Process Optimization and Screening for Biological Activity Type de document : texte imprimé Auteurs : Inês Mota, Auteur ; Paula C. Rodrigues Pinto, Auteur ; Catarina Novo, Auteur Année de publication : 2012 Article en page(s) : pp. 6991-7000 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Biological activity Optimization Bark Résumé : The bark of Eucalyptus globulus is a promising source of polyphenolic compounds that could be extracted employing polar solvents. Extraction experiments were planned according to the Box-Behnken design to evaluate the effect of temperature and time of extraction and the ethanol/water ratio on the dependent variables total phenolic content (TPC; as gallic acid equivalents, GAE), antioxidant activity (AA; as millimoles of ascorbic acid equivalents, AAE), proanthocyanidins (Pac; as mimosa extract equivalents, MEE), Stiasny number (SN), and coextracted total carbohydrates (TC). Response surface models were developed, and statistical analysis of variance was performed. A maximum of TPC of 32% (wGAE/wextract) was achieved for 264 min, 82.5 °C, and 52% ethanol corresponding to about 2% of the bark weight. These conditions are close to those leading to maximum values of compounds with AA (2.1 mmolAAE/gextract) and Pac 14% (wMEE/wextract). TC in the extract and the SN predicted were 22.7% (wTC/wextract) and 37, respectively. Preliminary studies concerning the biological activity of some extracts have demonstrated their differential capacity to reduce human breast cancer cell proliferation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925040
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 6991-7000[article] Extraction of Polyphenolic Compounds from Eucalyptus globulus Bark : Process Optimization and Screening for Biological Activity [texte imprimé] / Inês Mota, Auteur ; Paula C. Rodrigues Pinto, Auteur ; Catarina Novo, Auteur . - 2012 . - pp. 6991-7000.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 6991-7000
Mots-clés : Biological activity Optimization Bark Résumé : The bark of Eucalyptus globulus is a promising source of polyphenolic compounds that could be extracted employing polar solvents. Extraction experiments were planned according to the Box-Behnken design to evaluate the effect of temperature and time of extraction and the ethanol/water ratio on the dependent variables total phenolic content (TPC; as gallic acid equivalents, GAE), antioxidant activity (AA; as millimoles of ascorbic acid equivalents, AAE), proanthocyanidins (Pac; as mimosa extract equivalents, MEE), Stiasny number (SN), and coextracted total carbohydrates (TC). Response surface models were developed, and statistical analysis of variance was performed. A maximum of TPC of 32% (wGAE/wextract) was achieved for 264 min, 82.5 °C, and 52% ethanol corresponding to about 2% of the bark weight. These conditions are close to those leading to maximum values of compounds with AA (2.1 mmolAAE/gextract) and Pac 14% (wMEE/wextract). TC in the extract and the SN predicted were 22.7% (wTC/wextract) and 37, respectively. Preliminary studies concerning the biological activity of some extracts have demonstrated their differential capacity to reduce human breast cancer cell proliferation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925040 Exemplaires
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Titre : Depolymerization of ODPA/ODA polyimide in a fused silica capillary reactor and batch autoclave reactor from 320 to 350 °C in Hot compressed water Type de document : texte imprimé Auteurs : Fen Huang, Auteur ; Yuanyuan Huang, Auteur ; Zhiyan Pan, Auteur Année de publication : 2012 Article en page(s) : pp. 7001-7006 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Autoclave Batchwise Reactor Résumé : Depolymerization of polyimide synthesized from 4,4'-oxidiphthalic anhydride and 4,4'-diaminodiphenyl ether monomers (ODPA/ODA PI) in hot compressed water was carried out in a fused silica capillary reactor (FSCR) and batch autoclave reactor system. The phase behavior of ODPA/ODA PI in water during the heating, reaction, and cooling stages of the process in FSCR was observed with an image recording system from under the microscope. The effects of temperature (320―350 °C) and reaction time (30―90 min) on the depolymerization yield and products yields in batch autoclave reactor were investigated at a fixed H2O/PI ratio, and optimal conditions were established. Additionally, an understanding of the reaction pathway of ODPA/ODA PI depolymerization in hot compressed water was developed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925041
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7001-7006[article] Depolymerization of ODPA/ODA polyimide in a fused silica capillary reactor and batch autoclave reactor from 320 to 350 °C in Hot compressed water [texte imprimé] / Fen Huang, Auteur ; Yuanyuan Huang, Auteur ; Zhiyan Pan, Auteur . - 2012 . - pp. 7001-7006.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7001-7006
Mots-clés : Autoclave Batchwise Reactor Résumé : Depolymerization of polyimide synthesized from 4,4'-oxidiphthalic anhydride and 4,4'-diaminodiphenyl ether monomers (ODPA/ODA PI) in hot compressed water was carried out in a fused silica capillary reactor (FSCR) and batch autoclave reactor system. The phase behavior of ODPA/ODA PI in water during the heating, reaction, and cooling stages of the process in FSCR was observed with an image recording system from under the microscope. The effects of temperature (320―350 °C) and reaction time (30―90 min) on the depolymerization yield and products yields in batch autoclave reactor were investigated at a fixed H2O/PI ratio, and optimal conditions were established. Additionally, an understanding of the reaction pathway of ODPA/ODA PI depolymerization in hot compressed water was developed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925041 Exemplaires
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Titre : Effect of Fe(III) / citrate concentrations and ratio on the photoproduction of hydroxyl radicals : Application on the degradation of diphenhydramine Type de document : texte imprimé Auteurs : Xiaonan Feng, Auteur ; Zongping Wang, Auteur ; Chen, Yong, Auteur Année de publication : 2012 Article en page(s) : pp. 7007–7012 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydroxyl radicals Diphenhydramine Résumé : Fe(III)-citrate complexes are photoreactive and ubiquitous in natural waters. In this study, the effect of Fe(III)/citrate concentrations and ratio on the photoproduction of •OH as a function of pH (3–9) was systematically investigated. The •OH formation mechanism was elucidated according to the pH-dependent formation rate of •OH and the speciation distribution analysis of Fe(III) species. At high Fe(III)-to-citrate ratio (10:50), the •OH photoproduction increased with decreasing pH. In contrast, the •OH photoproduction increased in the order of pH 9.0 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300360p
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7007–7012[article] Effect of Fe(III) / citrate concentrations and ratio on the photoproduction of hydroxyl radicals : Application on the degradation of diphenhydramine [texte imprimé] / Xiaonan Feng, Auteur ; Zongping Wang, Auteur ; Chen, Yong, Auteur . - 2012 . - pp. 7007–7012.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7007–7012
Mots-clés : Hydroxyl radicals Diphenhydramine Résumé : Fe(III)-citrate complexes are photoreactive and ubiquitous in natural waters. In this study, the effect of Fe(III)/citrate concentrations and ratio on the photoproduction of •OH as a function of pH (3–9) was systematically investigated. The •OH formation mechanism was elucidated according to the pH-dependent formation rate of •OH and the speciation distribution analysis of Fe(III) species. At high Fe(III)-to-citrate ratio (10:50), the •OH photoproduction increased with decreasing pH. In contrast, the •OH photoproduction increased in the order of pH 9.0 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300360p Exemplaires
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Titre : Thermally driven copper oxide redox cycle for the separation of oxygen from gases Type de document : texte imprimé Auteurs : M. Hanchen, Auteur ; A. Stiel, Auteur ; Z. R. Jovanovic, Auteur Année de publication : 2012 Article en page(s) : pp. 7013–7021 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Copper Oxide Separation oxygen gases Résumé : The copper(I) oxide (Cu2O)/copper(II) oxide (CuO) redox thermochemical cycle is thermodynamically and experimentally examined as means for removal of oxygen from dilute gas streams. The thermal energy required for removal of oxygen from a 1% O2–Ar gas mixture is estimated to range from 545 to 2121 kJ/mol O2. Temperatures as high as 1350 K imposed by this thermochemical cycle offer potential for using concentrated solar energy as the source of process heat. The kinetics of the redox reactions and their cycle-to-cycle repeatability were investigated by thermogravimetry. Laboratory scale packed bed reactor tests have pointed out the bulk shrinking of the packing during the initial high temperature cycles as a cause of gas bypassing that may have adverse effects on the reactor contacting efficiency. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202474s
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7013–7021[article] Thermally driven copper oxide redox cycle for the separation of oxygen from gases [texte imprimé] / M. Hanchen, Auteur ; A. Stiel, Auteur ; Z. R. Jovanovic, Auteur . - 2012 . - pp. 7013–7021.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7013–7021
Mots-clés : Copper Oxide Separation oxygen gases Résumé : The copper(I) oxide (Cu2O)/copper(II) oxide (CuO) redox thermochemical cycle is thermodynamically and experimentally examined as means for removal of oxygen from dilute gas streams. The thermal energy required for removal of oxygen from a 1% O2–Ar gas mixture is estimated to range from 545 to 2121 kJ/mol O2. Temperatures as high as 1350 K imposed by this thermochemical cycle offer potential for using concentrated solar energy as the source of process heat. The kinetics of the redox reactions and their cycle-to-cycle repeatability were investigated by thermogravimetry. Laboratory scale packed bed reactor tests have pointed out the bulk shrinking of the packing during the initial high temperature cycles as a cause of gas bypassing that may have adverse effects on the reactor contacting efficiency. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202474s Exemplaires
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Titre : Effect of preheating treatment on the measured heats of adsorption of organic probes on clays with different surface compositions Type de document : texte imprimé Auteurs : Nayef El-Thaher, Auteur ; Phillip Choi, Auteur Année de publication : 2012 Article en page(s) : pp. 7022–7027 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Preheating treatment Adsorption Organic Clays Résumé : The effect of column preconditioning temperature (Tcp) on the measured heats of adsorption of selected aliphatic and aromatic compounds for kaolinite and illite, two clay minerals commonly encountered in the oil sands industry, was studied using the technique of inverse gas chromatography (IGC). Tcp was varied from 100 to 340 °C. Our results showed that, as Tcp was increased from 100 to 170 °C, the heats of adsorption (affinities) of the selected aliphatic solutes for kaolinite increased slightly, but those for illite stayed nearly the same. At higher Tcp values (170–230 °C), solute adsorption exhibited essentially no dependence on Tcp for both kaolinite and illite. This observation is attributed to the decreasing hydrophilicity for kaolinite from 100 to 170 °C, but not for kaolinite from 170 to 230 °C or for illite from 100 to 230 °C. Higher Tcp values (230–340 °C) were used for the two aromatic solutes (benzene and toluene), and it was found that their heats of adsorption for illite were significantly reduced (50%) whereas those for kaolinite were insensitive to Tcp. It is believed that this observation can be attributed to the loss of surface water as a result of increasing temperature. Here, departure of surface water would decrease the number of Lewis acid sites on the tetrahedral surfaces, thereby reducing the attractive interaction between the surfaces and the π bonds of the aromatic solutes at elevated Tcp. Because illite contains only tetrahedral surfaces, the measured heats of adsorption of benzene and toluene decreased with increasing temperature. However, in the case of kaolinite, which contains 1:1 tetrahedral and octahedral surfaces, this effect was offset by the increasing attractive interaction between the exposed hydroxyl moieties on the octahedral surfaces and the π bonds of the aromatic probes. As demonstrated in this work, the measured heat of adsorption depends on Tcp. Therefore, care must be taken when comparing solute affinity for various types of minerals based on IGC measurements. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202739x
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7022–7027[article] Effect of preheating treatment on the measured heats of adsorption of organic probes on clays with different surface compositions [texte imprimé] / Nayef El-Thaher, Auteur ; Phillip Choi, Auteur . - 2012 . - pp. 7022–7027.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7022–7027
Mots-clés : Preheating treatment Adsorption Organic Clays Résumé : The effect of column preconditioning temperature (Tcp) on the measured heats of adsorption of selected aliphatic and aromatic compounds for kaolinite and illite, two clay minerals commonly encountered in the oil sands industry, was studied using the technique of inverse gas chromatography (IGC). Tcp was varied from 100 to 340 °C. Our results showed that, as Tcp was increased from 100 to 170 °C, the heats of adsorption (affinities) of the selected aliphatic solutes for kaolinite increased slightly, but those for illite stayed nearly the same. At higher Tcp values (170–230 °C), solute adsorption exhibited essentially no dependence on Tcp for both kaolinite and illite. This observation is attributed to the decreasing hydrophilicity for kaolinite from 100 to 170 °C, but not for kaolinite from 170 to 230 °C or for illite from 100 to 230 °C. Higher Tcp values (230–340 °C) were used for the two aromatic solutes (benzene and toluene), and it was found that their heats of adsorption for illite were significantly reduced (50%) whereas those for kaolinite were insensitive to Tcp. It is believed that this observation can be attributed to the loss of surface water as a result of increasing temperature. Here, departure of surface water would decrease the number of Lewis acid sites on the tetrahedral surfaces, thereby reducing the attractive interaction between the surfaces and the π bonds of the aromatic solutes at elevated Tcp. Because illite contains only tetrahedral surfaces, the measured heats of adsorption of benzene and toluene decreased with increasing temperature. However, in the case of kaolinite, which contains 1:1 tetrahedral and octahedral surfaces, this effect was offset by the increasing attractive interaction between the exposed hydroxyl moieties on the octahedral surfaces and the π bonds of the aromatic probes. As demonstrated in this work, the measured heat of adsorption depends on Tcp. Therefore, care must be taken when comparing solute affinity for various types of minerals based on IGC measurements. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202739x Exemplaires
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Titre : Phosphorus distribution between liquid iron and magnesia - saturated slag in H2 / H2O atmosphere relevant to a novel ironmaking technology Type de document : texte imprimé Auteurs : M. Y. Mohassab-Ahmed, Auteur ; H. Y. Sohn, Auteur ; Hang Goo Kim, Auteur Année de publication : 2012 Article en page(s) : pp. 7028-7034 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Slag Résumé : As a part of a research project that aims to develop a novel ironmaking process using hydrogen flash reduction of iron ore concentrate, experimental determination of the phosphorus distribution ratio (Lp) between CaO―MgO(saturated)―SiO2― Al2O3―FeO slag and molten iron was determined in the temperature range 1550―1650 °C. Oxygen partial pressure was controlled by H2/H2O equilibrium in the range of 10―10―10―8 atm. Under these conditions applicable to the proposed process, Lp was 9—21. The proposed process is expected to produce iron with phosphorus content 7—14 times lower than in the iron produced by the blast furnace, considering the relative amounts of phosphorus inputs in the two processes and the low P content in the slag under the blast furnace conditions. This will decrease the need for dephosphorization in the steelmaking stage. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925045
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7028-7034[article] Phosphorus distribution between liquid iron and magnesia - saturated slag in H2 / H2O atmosphere relevant to a novel ironmaking technology [texte imprimé] / M. Y. Mohassab-Ahmed, Auteur ; H. Y. Sohn, Auteur ; Hang Goo Kim, Auteur . - 2012 . - pp. 7028-7034.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7028-7034
Mots-clés : Slag Résumé : As a part of a research project that aims to develop a novel ironmaking process using hydrogen flash reduction of iron ore concentrate, experimental determination of the phosphorus distribution ratio (Lp) between CaO―MgO(saturated)―SiO2― Al2O3―FeO slag and molten iron was determined in the temperature range 1550―1650 °C. Oxygen partial pressure was controlled by H2/H2O equilibrium in the range of 10―10―10―8 atm. Under these conditions applicable to the proposed process, Lp was 9—21. The proposed process is expected to produce iron with phosphorus content 7—14 times lower than in the iron produced by the blast furnace, considering the relative amounts of phosphorus inputs in the two processes and the low P content in the slag under the blast furnace conditions. This will decrease the need for dephosphorization in the steelmaking stage. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925045 Exemplaires
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Titre : An efficient method of constructing pinch point curves and locating azeotropes in nonideal distillation systems Type de document : texte imprimé Auteurs : N. Felbab, Auteur Année de publication : 2012 Article en page(s) : pp. 7035-7055 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Distillation Azeotropic mixture Résumé : An efficient, robust, ODE-based formulation of the continuation problem is presented for the automatic construction of all branches of the pinch point curves in any homogeneous distillation system (even highly nonideal ones) that can be represented using an activity coefficient model, with any number of components and for any adiabatic, nonreactive column configuration. Constant molar overflow is assumed. The curve is parametrized by reflux ratio, making it particularly applicable to distillation design and synthesis. Naturally, it can be used to find pinch point locations at a given finite reflux, as this is simply a subset of the pinch point curve. The method can also automatically locate all N-component azeotropes very efficiently (orders of magnitude faster than commercial process simulators). It has the additional advantage of being solvable using tools already available in typical mathematical software packages. A computer implementation of the proposed method is available. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925046
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7035-7055[article] An efficient method of constructing pinch point curves and locating azeotropes in nonideal distillation systems [texte imprimé] / N. Felbab, Auteur . - 2012 . - pp. 7035-7055.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7035-7055
Mots-clés : Distillation Azeotropic mixture Résumé : An efficient, robust, ODE-based formulation of the continuation problem is presented for the automatic construction of all branches of the pinch point curves in any homogeneous distillation system (even highly nonideal ones) that can be represented using an activity coefficient model, with any number of components and for any adiabatic, nonreactive column configuration. Constant molar overflow is assumed. The curve is parametrized by reflux ratio, making it particularly applicable to distillation design and synthesis. Naturally, it can be used to find pinch point locations at a given finite reflux, as this is simply a subset of the pinch point curve. The method can also automatically locate all N-component azeotropes very efficiently (orders of magnitude faster than commercial process simulators). It has the additional advantage of being solvable using tools already available in typical mathematical software packages. A computer implementation of the proposed method is available. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925046 Exemplaires
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Titre : Kinetic study and scaleup of the oxidation of nanofiltration retentates by O3 Type de document : texte imprimé Auteurs : Steven Van Geluwe, Auteur ; Jan Degreve, Auteur ; Chris Vinckier, Auteur Année de publication : 2012 Article en page(s) : pp. 7056-7066 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Membrane separation Nanofiltration Oxidation Kinetics Résumé : This paper reports on the upscaling of an O3 reactor for the oxidation of natural organic matter. Natural organic matter is responsible for fouling of nanofiltration membranes used for drinking water production. The proposed concept is to feed the retentate stream of a nanofiltration module (400 m3 h―1) to an O3 reactor (bubble column) and subsequently recycle it to a second nanofiltration module. The O3 oxidation of the retentate stream in the bubble column is analyzed in terms of the two-film theory with mass transfer and chemical reaction. The kinetic regime of the ozonation process, i.e., the chemical reaction rate relative to the mass-transfer rate, is determined using data from laboratory-scale experiments. This information is used for the calculation of the reactor volume and the required O3 dose on an industrial scale. An economic assessment of the integrated nanofiltration―O3 oxidation process also is given. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925047
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7056-7066[article] Kinetic study and scaleup of the oxidation of nanofiltration retentates by O3 [texte imprimé] / Steven Van Geluwe, Auteur ; Jan Degreve, Auteur ; Chris Vinckier, Auteur . - 2012 . - pp. 7056-7066.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7056-7066
Mots-clés : Membrane separation Nanofiltration Oxidation Kinetics Résumé : This paper reports on the upscaling of an O3 reactor for the oxidation of natural organic matter. Natural organic matter is responsible for fouling of nanofiltration membranes used for drinking water production. The proposed concept is to feed the retentate stream of a nanofiltration module (400 m3 h―1) to an O3 reactor (bubble column) and subsequently recycle it to a second nanofiltration module. The O3 oxidation of the retentate stream in the bubble column is analyzed in terms of the two-film theory with mass transfer and chemical reaction. The kinetic regime of the ozonation process, i.e., the chemical reaction rate relative to the mass-transfer rate, is determined using data from laboratory-scale experiments. This information is used for the calculation of the reactor volume and the required O3 dose on an industrial scale. An economic assessment of the integrated nanofiltration―O3 oxidation process also is given. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925047 Exemplaires
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Titre : Experimental determination of bubble size distributions in laboratory scale sieve tray with mesh Type de document : texte imprimé Auteurs : Weiwen Wang, Auteur ; Suya Li, Auteur ; Jianlong Li, Auteur Année de publication : 2012 Article en page(s) : pp. 7067-7072 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Perforated tray Laboratory scale Particle size distribution Bubble Résumé : Most applications on sieve tray intemals were internals additions for increasing bubble area and changing gas liquid contact form to intensify the mass transfer in a tower. An easy improvement to set up a mesh on the sieve tray was proposed in this paper. It was confirmed that foam layer on the sieve tray acts as the main role of mass transfer. The mesh here could turn large bubbles into such small ones that gas would contact with the liquid sufficiently and also could avoid many small bubbles coalescing into large ones. Meanwhile, interfacial area was enlarged greatly, which was of benefit to mass transfer. In addition, the mesh could make small bubbles have a long stay time in trays, an advantage for mass transfer. In this paper, the gas hold-up and tray pressure drop were determined in an air―water system under isothermal conditions. Mean bubble diameter was measured by CCD in a 0.12 m diameter tower, and bubble radial distributions and probability density functions were also determined. The experimental results proved that mesh could obtain more total gas hold-up and reduce the bubble mean diameter greatly but increased the tray pressure drop severely also. The existence of mesh did not change the trend of bubble flow on the tray. The greatest bubbles still concentrated in the center and gradually reduced to the wall along the radial direction; the small bubbles turned into large ones along the height, and the distribution became wider at higher positions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925048
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7067-7072[article] Experimental determination of bubble size distributions in laboratory scale sieve tray with mesh [texte imprimé] / Weiwen Wang, Auteur ; Suya Li, Auteur ; Jianlong Li, Auteur . - 2012 . - pp. 7067-7072.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7067-7072
Mots-clés : Perforated tray Laboratory scale Particle size distribution Bubble Résumé : Most applications on sieve tray intemals were internals additions for increasing bubble area and changing gas liquid contact form to intensify the mass transfer in a tower. An easy improvement to set up a mesh on the sieve tray was proposed in this paper. It was confirmed that foam layer on the sieve tray acts as the main role of mass transfer. The mesh here could turn large bubbles into such small ones that gas would contact with the liquid sufficiently and also could avoid many small bubbles coalescing into large ones. Meanwhile, interfacial area was enlarged greatly, which was of benefit to mass transfer. In addition, the mesh could make small bubbles have a long stay time in trays, an advantage for mass transfer. In this paper, the gas hold-up and tray pressure drop were determined in an air―water system under isothermal conditions. Mean bubble diameter was measured by CCD in a 0.12 m diameter tower, and bubble radial distributions and probability density functions were also determined. The experimental results proved that mesh could obtain more total gas hold-up and reduce the bubble mean diameter greatly but increased the tray pressure drop severely also. The existence of mesh did not change the trend of bubble flow on the tray. The greatest bubbles still concentrated in the center and gradually reduced to the wall along the radial direction; the small bubbles turned into large ones along the height, and the distribution became wider at higher positions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925048 Exemplaires
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Titre : 1,3 - Butadiene adsorption over transition metal polycation exchanged faujasites Type de document : texte imprimé Auteurs : Albert M. Tsybulevski, Auteur ; Leonid M. Kustov, Auteur ; Kerry C. Weston, Auteur Année de publication : 2012 Article en page(s) : pp. 7073-7080 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Adsorption Résumé : New adsorbents for butadiene removal from liquid and gas streams, which are transition metal (Cu, Zn, Mn) polycation exchanged zeolites, were prepared on the basis of low-silica and dealuminated faujasites by ion exchange with the corresponding salt solutions at the conditions of their partial hydrolysis. Obtained samples were characterized by XANES, ESR, and DRIFT spectroscopy along with equilibrium and dynamic adsorption studies. It is shown that transition metal polycation containing faujasites significantly surpass monocation analogues with respect to butadiene adsorption capacity. It is also found that an enhanced ability to adsorb butadiene is peculiar to faujasites with strong acidity that defines the activity of the adsorbent in the oligomerization of adsorbed butadiene. The suggested adsorbents are fully regenerable at gradual elevation of regeneration temperature up to 250―350 °C. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925049
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7073-7080[article] 1,3 - Butadiene adsorption over transition metal polycation exchanged faujasites [texte imprimé] / Albert M. Tsybulevski, Auteur ; Leonid M. Kustov, Auteur ; Kerry C. Weston, Auteur . - 2012 . - pp. 7073-7080.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7073-7080
Mots-clés : Adsorption Résumé : New adsorbents for butadiene removal from liquid and gas streams, which are transition metal (Cu, Zn, Mn) polycation exchanged zeolites, were prepared on the basis of low-silica and dealuminated faujasites by ion exchange with the corresponding salt solutions at the conditions of their partial hydrolysis. Obtained samples were characterized by XANES, ESR, and DRIFT spectroscopy along with equilibrium and dynamic adsorption studies. It is shown that transition metal polycation containing faujasites significantly surpass monocation analogues with respect to butadiene adsorption capacity. It is also found that an enhanced ability to adsorb butadiene is peculiar to faujasites with strong acidity that defines the activity of the adsorbent in the oligomerization of adsorbed butadiene. The suggested adsorbents are fully regenerable at gradual elevation of regeneration temperature up to 250―350 °C. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925049 Exemplaires
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Titre : Age distribution in the kenics static micromixer with convection and diffusion Type de document : texte imprimé Auteurs : Minye Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 7081-7094 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Diffusion Convection Micromixing Résumé : Age distribution in a Kenics static micromixer is studied by mean age solution of a steady transport equation. The spatial distribution of mean age reveals locations of older material that could potentially cause process fouling and product defects. At the microscales of the mixer, both convection and diffusion strongly affect age distribution. A method is developed to compute an average effective diffusivity to measure false diffusion due to numerical errors. The range of Peclet number is found so that the scalar solution is not affected by false diffusion. The effect of convection and diffusion is studied for Re numbers that cover the full range of laminar flows in the mixer. Diffusion broadening is found to have a strong effect on the striation structures in the mixer. Age distribution in the mixer is quantitatively measured with a frequency distribution function and two different variances, the variance of residence time and the variance of mean age. It is found that the mean age variance decay rate increases almost monotonically as Re increases. It is shown that the distribution of mean age is always narrower than that of residence time. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925050
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7081-7094[article] Age distribution in the kenics static micromixer with convection and diffusion [texte imprimé] / Minye Liu, Auteur . - 2012 . - pp. 7081-7094.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7081-7094
Mots-clés : Diffusion Convection Micromixing Résumé : Age distribution in a Kenics static micromixer is studied by mean age solution of a steady transport equation. The spatial distribution of mean age reveals locations of older material that could potentially cause process fouling and product defects. At the microscales of the mixer, both convection and diffusion strongly affect age distribution. A method is developed to compute an average effective diffusivity to measure false diffusion due to numerical errors. The range of Peclet number is found so that the scalar solution is not affected by false diffusion. The effect of convection and diffusion is studied for Re numbers that cover the full range of laminar flows in the mixer. Diffusion broadening is found to have a strong effect on the striation structures in the mixer. Age distribution in the mixer is quantitatively measured with a frequency distribution function and two different variances, the variance of residence time and the variance of mean age. It is found that the mean age variance decay rate increases almost monotonically as Re increases. It is shown that the distribution of mean age is always narrower than that of residence time. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925050 Exemplaires
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Titre : Two - layer model for horizontal pipe flow of newtonian and non - newtonian settling dense slurries Type de document : texte imprimé Auteurs : Mario R. Rojas, Auteur ; A. Eduardo Saez, Auteur Année de publication : 2012 Article en page(s) : pp. 7095-7103 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Sedimentation Pipe flow Modeling Résumé : The steady-state flow of Newtonian and non-Newtonian dense aqueous slurries in horizontal pipes has been analyzed using a two-layer model, consisting of a top layer of flowing suspension and a bottom bed of stationary or moving particles. The coarse solids used have a wide range of particle density and particle size distributions. The fluids studied were designed to simulate U.S. Department of Energy Hanford site waste slurries. The most important changes from previous models include an independent settling analysis for different particle size fractions, effects of particle shape on settling velocity, and a new correlation for the turbulent particle dispersivity. The results indicate that the turbulent dispersivity of settling particles is sensitive to particle size and density. The model gives good estimation of the critical deposition velocity as the minimum of the pressure drop versus superficial slurry velocity relation. The existence of a stationary layer can be observed and predicted by the model under laminar and turbulent flow conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925051
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7095-7103[article] Two - layer model for horizontal pipe flow of newtonian and non - newtonian settling dense slurries [texte imprimé] / Mario R. Rojas, Auteur ; A. Eduardo Saez, Auteur . - 2012 . - pp. 7095-7103.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7095-7103
Mots-clés : Sedimentation Pipe flow Modeling Résumé : The steady-state flow of Newtonian and non-Newtonian dense aqueous slurries in horizontal pipes has been analyzed using a two-layer model, consisting of a top layer of flowing suspension and a bottom bed of stationary or moving particles. The coarse solids used have a wide range of particle density and particle size distributions. The fluids studied were designed to simulate U.S. Department of Energy Hanford site waste slurries. The most important changes from previous models include an independent settling analysis for different particle size fractions, effects of particle shape on settling velocity, and a new correlation for the turbulent particle dispersivity. The results indicate that the turbulent dispersivity of settling particles is sensitive to particle size and density. The model gives good estimation of the critical deposition velocity as the minimum of the pressure drop versus superficial slurry velocity relation. The existence of a stationary layer can be observed and predicted by the model under laminar and turbulent flow conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925051 Exemplaires
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Titre : Time – frequency analysis based flow regime identification methods for airlift reactors Type de document : texte imprimé Auteurs : Lijia Luo, Auteur ; Ying Yan, Auteur ; Yuanyuan Xu, Auteur Année de publication : 2012 Article en page(s) : pp. 7104-7112 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Bioreactor Airlift reactor Flow regime Résumé : The flow regime transitions in an airlift reactor were investigated based on pressure fluctuation signals. Two time―frequency analysis methods, i.e., Wigner―Ville distribution and wavelet transform, were used to extract flow regime characteristics from pressure signals. The main frequency derived from the smoothed pseudo-Wigner―Ville distribution of the pressure signal was used to quantify flow regime transitions in the reactor. Two flow regime transition points were successfully detected from the evolution of main frequencies of pressure signals. In addition, the local dynamic characteristics of the pressure signal at different frequency bands were analyzed by use of the wavelet transform. A new flow regime identification method based on the wavelet entropy of the pressure signal was proposed. This method was confirmed to be reliable and efficient to detect flow regime transitions in the reactor. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925052
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7104-7112[article] Time – frequency analysis based flow regime identification methods for airlift reactors [texte imprimé] / Lijia Luo, Auteur ; Ying Yan, Auteur ; Yuanyuan Xu, Auteur . - 2012 . - pp. 7104-7112.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7104-7112
Mots-clés : Bioreactor Airlift reactor Flow regime Résumé : The flow regime transitions in an airlift reactor were investigated based on pressure fluctuation signals. Two time―frequency analysis methods, i.e., Wigner―Ville distribution and wavelet transform, were used to extract flow regime characteristics from pressure signals. The main frequency derived from the smoothed pseudo-Wigner―Ville distribution of the pressure signal was used to quantify flow regime transitions in the reactor. Two flow regime transition points were successfully detected from the evolution of main frequencies of pressure signals. In addition, the local dynamic characteristics of the pressure signal at different frequency bands were analyzed by use of the wavelet transform. A new flow regime identification method based on the wavelet entropy of the pressure signal was proposed. This method was confirmed to be reliable and efficient to detect flow regime transitions in the reactor. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925052 Exemplaires
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Titre : Micromixing efficiency of viscous media in novel impinging stream - rotating packed bed reactor Type de document : texte imprimé Auteurs : Weizhou Jiao, Auteur ; Youzhi Liu, Auteur ; Guisheng Qi, Auteur Année de publication : 2012 Article en page(s) : pp. 7113-7118 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Impinging stream Fixed bed reactor Micromixing Résumé : Micromixing efficiency of viscous media in novel IS-RPB reactor was studied by using iodide-iodate test reaction as working system. Experiments were carried out in glycerol-water solution with different viscosities. The effects of high gravity factor, liquid flow rate, acid concentration, liquid flow ratio, and viscosity on segregation index and micromixing time were investigated. The experimental results showed that the IS-RPB was effective in enhancing micromixing when the liquid viscosity increased. Furthermore, the micromixing time tm of the IS-RPB reactor was determined based on the incorporation model, and its value was in the range of 10―5―10―4 s. Compared with other mixing devices, IS-RPB reactor has better micromixing characteristics than other reactors, which has a good application prospect. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925053
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7113-7118[article] Micromixing efficiency of viscous media in novel impinging stream - rotating packed bed reactor [texte imprimé] / Weizhou Jiao, Auteur ; Youzhi Liu, Auteur ; Guisheng Qi, Auteur . - 2012 . - pp. 7113-7118.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7113-7118
Mots-clés : Impinging stream Fixed bed reactor Micromixing Résumé : Micromixing efficiency of viscous media in novel IS-RPB reactor was studied by using iodide-iodate test reaction as working system. Experiments were carried out in glycerol-water solution with different viscosities. The effects of high gravity factor, liquid flow rate, acid concentration, liquid flow ratio, and viscosity on segregation index and micromixing time were investigated. The experimental results showed that the IS-RPB was effective in enhancing micromixing when the liquid viscosity increased. Furthermore, the micromixing time tm of the IS-RPB reactor was determined based on the incorporation model, and its value was in the range of 10―5―10―4 s. Compared with other mixing devices, IS-RPB reactor has better micromixing characteristics than other reactors, which has a good application prospect. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925053 Exemplaires
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Titre : Determination of vapor pressure of chemical compounds : A group contribution model for an extremely large database Type de document : texte imprimé Auteurs : Farhad Gharagheizi, Auteur ; Ali Eslamimanesh, Auteur ; Poorandokht Ilani-Kashkouli, Auteur Année de publication : 2012 Article en page(s) : pp. 7119-7125 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Database Modeling Chemical compound Vapor pressure Résumé : In the present study, a group contribution model is developed for determination of the vapor pressure of pure chemical compounds at temperatures from 55 to 3040 K. About 42 000 vapor pressure values belonging to around 1400 chemical compounds (mostly organic ones) at different temperatures are treated to propose a reliable and predictive model. A three-layer artificial neural network is optimized using the Levenberg―Marquardt (LM) optimization algorithm to establish the final relationship between the functional groups and the vapor pressure values. The obtained results indicate the average absolute relative deviation (AARD%) of the calculations/estimations from the applied data to be about 6% and a squared correlation coefficient of 0.994. Furthermore, the outliers of the model are detected using the leverage value statistics method. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925054
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7119-7125[article] Determination of vapor pressure of chemical compounds : A group contribution model for an extremely large database [texte imprimé] / Farhad Gharagheizi, Auteur ; Ali Eslamimanesh, Auteur ; Poorandokht Ilani-Kashkouli, Auteur . - 2012 . - pp. 7119-7125.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7119-7125
Mots-clés : Database Modeling Chemical compound Vapor pressure Résumé : In the present study, a group contribution model is developed for determination of the vapor pressure of pure chemical compounds at temperatures from 55 to 3040 K. About 42 000 vapor pressure values belonging to around 1400 chemical compounds (mostly organic ones) at different temperatures are treated to propose a reliable and predictive model. A three-layer artificial neural network is optimized using the Levenberg―Marquardt (LM) optimization algorithm to establish the final relationship between the functional groups and the vapor pressure values. The obtained results indicate the average absolute relative deviation (AARD%) of the calculations/estimations from the applied data to be about 6% and a squared correlation coefficient of 0.994. Furthermore, the outliers of the model are detected using the leverage value statistics method. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925054 Exemplaires
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Titre : Drug release from poly (dimethylsiloxane) - based matrices : Observed and predicted stabilization of the release rate by three - layer devices Type de document : texte imprimé Auteurs : Dimitrios N. Soulas, Auteur ; Kyriaki G. Papadokostaki, Auteur ; Athanasia Panou, Auteur Année de publication : 2012 Article en page(s) : pp. 7126-7136 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Stabilization Résumé : Realistic mathematical modeling can greatly facilitate the optimum design of matrix-controlled release (MCR) devices. Here, we present a practical example of a relevant methodology, based on a previously developed model for symmetrical, three-layer MCR devices. The experimental system is based on PDMS matrices incorporating 10% of poly(ethylene glycol) and loaded with theophylline. The matrices were either single-layer devices uniformly loaded with theophylline or symmetrical three-layer devices with a uniformly loaded inner layer and theophylline-free outer layers. The theophylline loads, and the geometrical characteristics of the multilayer matrices, were chosen according to general guidelines for improved uniformity of rate, previously formulated by model calculations. As anticipated, these devices were found to effectively stabilize the rate of release, as compared to the corresponding single-layer system. The main kinetic characteristics of the experimental systems were then successfully reproduced theoretically by a set of input parameters (pertaining to the transport properties of the polymer―solute―solvent system), derived mainly from the release experiments in monolithic matrices. Finally, the same input parameters were used for exploring theoretically the range of the three-layer device parameters that are expected to preserve the observed improved performance of the experimental systems. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925055
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7126-7136[article] Drug release from poly (dimethylsiloxane) - based matrices : Observed and predicted stabilization of the release rate by three - layer devices [texte imprimé] / Dimitrios N. Soulas, Auteur ; Kyriaki G. Papadokostaki, Auteur ; Athanasia Panou, Auteur . - 2012 . - pp. 7126-7136.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7126-7136
Mots-clés : Stabilization Résumé : Realistic mathematical modeling can greatly facilitate the optimum design of matrix-controlled release (MCR) devices. Here, we present a practical example of a relevant methodology, based on a previously developed model for symmetrical, three-layer MCR devices. The experimental system is based on PDMS matrices incorporating 10% of poly(ethylene glycol) and loaded with theophylline. The matrices were either single-layer devices uniformly loaded with theophylline or symmetrical three-layer devices with a uniformly loaded inner layer and theophylline-free outer layers. The theophylline loads, and the geometrical characteristics of the multilayer matrices, were chosen according to general guidelines for improved uniformity of rate, previously formulated by model calculations. As anticipated, these devices were found to effectively stabilize the rate of release, as compared to the corresponding single-layer system. The main kinetic characteristics of the experimental systems were then successfully reproduced theoretically by a set of input parameters (pertaining to the transport properties of the polymer―solute―solvent system), derived mainly from the release experiments in monolithic matrices. Finally, the same input parameters were used for exploring theoretically the range of the three-layer device parameters that are expected to preserve the observed improved performance of the experimental systems. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925055 Exemplaires
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