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Vol. 48 N° 9 - Mai 2009 [texte imprimé] . - 2009 . - p. 4177-4618 : ill. ; 28 cm. Chemical engineering Langues : Anglais (eng)
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Ajouter le résultat dans votre panierTransesterification of rice bran oil with methanol catalyzed by Mg(Al)La hydrotalcites and metal/MgAl oxides / Pacharaporn Chuayplod in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009)
Titre : Transesterification of rice bran oil with methanol catalyzed by Mg(Al)La hydrotalcites and metal/MgAl oxides Type de document : texte imprimé Auteurs : Pacharaporn Chuayplod, Auteur ; Wimonrat Trakarnpruk, Auteur Année de publication : 2009 Article en page(s) : pp. 4177–4183 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mg(Al)La hydrotalcites MgAl oxide Alkali-free coprecipitation method Catalytic activity Résumé : Both MgAl and Mg(Al)La hydrotalcites were synthesized by an alkali-free coprecipitation method and calcined to their corresponding oxides. MgAl oxide was impregnated with different kinds of metals (M = Cs, Sr, Ba, and La). All materials were characterized by the XRD, FT-IR, BET, NH3 TPD, and SEM techniques. The catalytic activity order of the M/MgAl oxides in the transesterification of glyceryl tributyrate (a model triglyceride) with methanol was found to be Cs > Ba ≈ Sr > La. The Mg(Al)La hydrotalcite that was calcined and then rehydrated contains Brønsted base sites, exhibiting higher activity than the calcined sample with Lewis base sites. In the preparation of biodiesel from rice bran oil via a two-step catalyzed process, crude rice bran oil (11.14% FFAs) was first dewaxed/degummed and then esterified using silica-supported heteropolyacid H3PW12O40. FFAs were decreased to 0.98% at 70 °C in 4 h. This oil was then transesterified with methanol using the rehydrated Mg(Al)La hydrotalcites. At a temperature of 100 °C, a reaction time of 9 h, a methanol/oil molar ratio of 30:1, and a catalyst content of 7.5 wt %, biodiesel with 97% ester content and 78% product yield was obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005947
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4177–4183[article] Transesterification of rice bran oil with methanol catalyzed by Mg(Al)La hydrotalcites and metal/MgAl oxides [texte imprimé] / Pacharaporn Chuayplod, Auteur ; Wimonrat Trakarnpruk, Auteur . - 2009 . - pp. 4177–4183.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4177–4183
Mots-clés : Mg(Al)La hydrotalcites MgAl oxide Alkali-free coprecipitation method Catalytic activity Résumé : Both MgAl and Mg(Al)La hydrotalcites were synthesized by an alkali-free coprecipitation method and calcined to their corresponding oxides. MgAl oxide was impregnated with different kinds of metals (M = Cs, Sr, Ba, and La). All materials were characterized by the XRD, FT-IR, BET, NH3 TPD, and SEM techniques. The catalytic activity order of the M/MgAl oxides in the transesterification of glyceryl tributyrate (a model triglyceride) with methanol was found to be Cs > Ba ≈ Sr > La. The Mg(Al)La hydrotalcite that was calcined and then rehydrated contains Brønsted base sites, exhibiting higher activity than the calcined sample with Lewis base sites. In the preparation of biodiesel from rice bran oil via a two-step catalyzed process, crude rice bran oil (11.14% FFAs) was first dewaxed/degummed and then esterified using silica-supported heteropolyacid H3PW12O40. FFAs were decreased to 0.98% at 70 °C in 4 h. This oil was then transesterified with methanol using the rehydrated Mg(Al)La hydrotalcites. At a temperature of 100 °C, a reaction time of 9 h, a methanol/oil molar ratio of 30:1, and a catalyst content of 7.5 wt %, biodiesel with 97% ester content and 78% product yield was obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005947 Exemplaires
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Titre : Carbon capture by sorption-enhanced water-gas shift reaction process using hydrotalcite-based material Type de document : texte imprimé Auteurs : E. R. van Selow, Auteur ; P. D. Cobden, Auteur ; P. A. Verbraeken, Auteur Année de publication : 2009 Article en page(s) : pp. 4184–4193 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sorption-enhanced water− gas shift process Carbon Adsorption Desorption Résumé : A novel route for precombustion decarbonization is the sorption-enhanced water−gas shift (SEWGS) process. In this process carbon dioxide is removed from a synthesis gas at elevated temperature by adsorption. Simultaneously, carbon monoxide is converted to carbon dioxide by the water−gas shift reaction. The periodic adsorption and desorption of carbon dioxide is induced by a pressure swing cycle, and the cyclic capacity can be amplified by purging with steam. From previous studies is it known that for SEWGS applications, hydrotalcite-based materials are particularly attractive as sorbent, and commercial high-temperature shift catalysts can be used for the conversion of carbon monoxide. Tablets of a potassium promoted hydrotalcite-based material are characterized in both breakthrough and cyclic experiments in a 2 m tall fixed-bed reactor. When exposed to a mixture of carbon dioxide, steam, and nitrogen at 400 °C, the material shows a breakthrough capacity of 1.4 mmol/g. The sharp adsorption front is accompanied by an exotherm that travels along the bed. Even after breakthrough carbon dioxide continues to be taken up by the bed albeit at a much lower rate. It is shown that the total capacity of this material can exceed 10 mmol/g, which has not been reported before. Desorption curves indicate efficiencies of removing additional carbon dioxide by purging with low-pressure, superheated steam at various flow rates. During cyclic operation for more than 1400 adsorption and desorption cycles, the carbon dioxide slip is very low and remains stable which indicates that carbon recoveries well above 90% can be obtained. The sorbent shows a stable cyclic capacity of 0.66 mmol/g. In subsequent experiments the material was mixed with tablets of promoted iron−chromium shift catalyst and exposed to a mixture of carbon dioxide, carbon monoxide, steam, hydrogen, and nitrogen. It is demonstrated that carbon monoxide conversion can be enhanced to 100% in the presence of a carbon dioxide sorbent. At breakthrough, carbon monoxide and carbon dioxide simultaneously appear at the end of the bed. During more than 300 cycles of adsorption/reaction and desorption, the capture rate, and carbon monoxide conversion are confirmed to be stable. Two different cycle types are investigated: one cycle with a CO2 rinse step and one cycle with a steam rinse step. The performance of both SEWGS cycles are discussed. These experimental results will allow optimization of process conditions and cycle parameters, and especially the reduction of steam consumption needed for sorbent regeneration. The results will provide the basis for scale-up to a pilot unit, which will demonstrate precombustion decarbonization in fossil-fuels-based power generation or hydrogen production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801713a
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4184–4193[article] Carbon capture by sorption-enhanced water-gas shift reaction process using hydrotalcite-based material [texte imprimé] / E. R. van Selow, Auteur ; P. D. Cobden, Auteur ; P. A. Verbraeken, Auteur . - 2009 . - pp. 4184–4193.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4184–4193
Mots-clés : Sorption-enhanced water− gas shift process Carbon Adsorption Desorption Résumé : A novel route for precombustion decarbonization is the sorption-enhanced water−gas shift (SEWGS) process. In this process carbon dioxide is removed from a synthesis gas at elevated temperature by adsorption. Simultaneously, carbon monoxide is converted to carbon dioxide by the water−gas shift reaction. The periodic adsorption and desorption of carbon dioxide is induced by a pressure swing cycle, and the cyclic capacity can be amplified by purging with steam. From previous studies is it known that for SEWGS applications, hydrotalcite-based materials are particularly attractive as sorbent, and commercial high-temperature shift catalysts can be used for the conversion of carbon monoxide. Tablets of a potassium promoted hydrotalcite-based material are characterized in both breakthrough and cyclic experiments in a 2 m tall fixed-bed reactor. When exposed to a mixture of carbon dioxide, steam, and nitrogen at 400 °C, the material shows a breakthrough capacity of 1.4 mmol/g. The sharp adsorption front is accompanied by an exotherm that travels along the bed. Even after breakthrough carbon dioxide continues to be taken up by the bed albeit at a much lower rate. It is shown that the total capacity of this material can exceed 10 mmol/g, which has not been reported before. Desorption curves indicate efficiencies of removing additional carbon dioxide by purging with low-pressure, superheated steam at various flow rates. During cyclic operation for more than 1400 adsorption and desorption cycles, the carbon dioxide slip is very low and remains stable which indicates that carbon recoveries well above 90% can be obtained. The sorbent shows a stable cyclic capacity of 0.66 mmol/g. In subsequent experiments the material was mixed with tablets of promoted iron−chromium shift catalyst and exposed to a mixture of carbon dioxide, carbon monoxide, steam, hydrogen, and nitrogen. It is demonstrated that carbon monoxide conversion can be enhanced to 100% in the presence of a carbon dioxide sorbent. At breakthrough, carbon monoxide and carbon dioxide simultaneously appear at the end of the bed. During more than 300 cycles of adsorption/reaction and desorption, the capture rate, and carbon monoxide conversion are confirmed to be stable. Two different cycle types are investigated: one cycle with a CO2 rinse step and one cycle with a steam rinse step. The performance of both SEWGS cycles are discussed. These experimental results will allow optimization of process conditions and cycle parameters, and especially the reduction of steam consumption needed for sorbent regeneration. The results will provide the basis for scale-up to a pilot unit, which will demonstrate precombustion decarbonization in fossil-fuels-based power generation or hydrogen production. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801713a Exemplaires
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Titre : “Rice polish” for the removal of arsenic from aqueous solution : optimization of process variables Type de document : texte imprimé Auteurs : S. H. Hasan, Auteur ; D. Ranjan, Auteur ; M. Talat, Auteur Année de publication : 2009 Article en page(s) : pp. 4194–4201 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Rice polish Aqueous solution Box− Behnken Design Polynomial regression model Résumé : Rice polish, a waste from the rice milling industry, was utilized as a potential biosorbent for removal of arsenic from aqueous solution. Optimization of process variables (pH, initial metal concentration, and temperature) and their cumulative effect were investigated using Box−Behnken Design (BBD) with only 15 sets of experimental runs. A second-order polynomial regression model was used, and results predicted showed high value of regression coefficients (R2, i.e., 95.69% for As(III) and 98.42% for As(V)) indicating good agreement with experimental data. The main effect plot showed uptake of arsenic having a curved relationship with pH, initial metal ion concentration having a positive effect, and temperature having a negative effect. The maximum removal of As(III) (41.18 μg/g) and As(V) (49 μg/g) predicted by contour and optimization plot was achieved at pH 6.84 and 4.29, respectively, at an initial metal ion concentration of 1000 μg/L, temperature 20 °C, and biomass dose of 1 g/50 mL. Scanning electron microscopy (SEM) analysis was carried out to find out the changes on the biosorbent surface during the sorption process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801822d
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4194–4201[article] “Rice polish” for the removal of arsenic from aqueous solution : optimization of process variables [texte imprimé] / S. H. Hasan, Auteur ; D. Ranjan, Auteur ; M. Talat, Auteur . - 2009 . - pp. 4194–4201.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4194–4201
Mots-clés : Rice polish Aqueous solution Box− Behnken Design Polynomial regression model Résumé : Rice polish, a waste from the rice milling industry, was utilized as a potential biosorbent for removal of arsenic from aqueous solution. Optimization of process variables (pH, initial metal concentration, and temperature) and their cumulative effect were investigated using Box−Behnken Design (BBD) with only 15 sets of experimental runs. A second-order polynomial regression model was used, and results predicted showed high value of regression coefficients (R2, i.e., 95.69% for As(III) and 98.42% for As(V)) indicating good agreement with experimental data. The main effect plot showed uptake of arsenic having a curved relationship with pH, initial metal ion concentration having a positive effect, and temperature having a negative effect. The maximum removal of As(III) (41.18 μg/g) and As(V) (49 μg/g) predicted by contour and optimization plot was achieved at pH 6.84 and 4.29, respectively, at an initial metal ion concentration of 1000 μg/L, temperature 20 °C, and biomass dose of 1 g/50 mL. Scanning electron microscopy (SEM) analysis was carried out to find out the changes on the biosorbent surface during the sorption process. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801822d Exemplaires
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Titre : Influence of catalysts on the preparation of carbon nanotubes for toluene oxidation Type de document : texte imprimé Auteurs : Kui H. Chuang, Auteur ; Zhen S. Liu, Auteur ; Chi Y. Lu, Auteur Année de publication : 2009 Article en page(s) : pp. 4202–4209 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Catalysts Carbon nanotubes Toluene oxidation Chemical vapor deposition method Résumé : This study aims to investigate the effect of catalysts on the preparation of carbon nanotubes (CNTs) and the catalytic properties of Co/CNT for toluene oxidation between 175 and 250 °C. A different ratio of Co to Mo supported on Al2O3 was used in the chemical vapor deposition method to synthesize the carbon nanotubes. Moreover, the catalytic activities of Al2O3-supported catalysts for toluene oxidation were also measured, and the results were compared with the catalytic activities of Co/CNT catalysts. To confirm the characterization of CNT and Co/CNT, the composition and morphology of various catalysts were analyzed by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectra, BET, and X-ray photoelectron spectroscopy (XPS). The results indicated that the catalytic activity of Co/CNT catalysts was higher than that of the Al2O3-supported catalysts. Furthermore, the catalytic activity of Co/CNT prepared by using 2.4% Co−0.6% Mo/Al2O3 for toluene oxidation was 100% at 225 °C. The results demonstrated that the removal efficiency of toluene depends on the species of catalysts synthesized on the carbon nanotubes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801692g
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4202–4209[article] Influence of catalysts on the preparation of carbon nanotubes for toluene oxidation [texte imprimé] / Kui H. Chuang, Auteur ; Zhen S. Liu, Auteur ; Chi Y. Lu, Auteur . - 2009 . - pp. 4202–4209.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4202–4209
Mots-clés : Catalysts Carbon nanotubes Toluene oxidation Chemical vapor deposition method Résumé : This study aims to investigate the effect of catalysts on the preparation of carbon nanotubes (CNTs) and the catalytic properties of Co/CNT for toluene oxidation between 175 and 250 °C. A different ratio of Co to Mo supported on Al2O3 was used in the chemical vapor deposition method to synthesize the carbon nanotubes. Moreover, the catalytic activities of Al2O3-supported catalysts for toluene oxidation were also measured, and the results were compared with the catalytic activities of Co/CNT catalysts. To confirm the characterization of CNT and Co/CNT, the composition and morphology of various catalysts were analyzed by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectra, BET, and X-ray photoelectron spectroscopy (XPS). The results indicated that the catalytic activity of Co/CNT catalysts was higher than that of the Al2O3-supported catalysts. Furthermore, the catalytic activity of Co/CNT prepared by using 2.4% Co−0.6% Mo/Al2O3 for toluene oxidation was 100% at 225 °C. The results demonstrated that the removal efficiency of toluene depends on the species of catalysts synthesized on the carbon nanotubes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801692g Exemplaires
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Titre : Green and efficient conversion of CO2 to methanol by biomimetic coimmobilization of three dehydrogenases in protamine-templated titania Type de document : texte imprimé Auteurs : Qianyun Sun, Auteur ; Yanjun Jiang, Auteur ; Zhongyi Jiang, Auteur Année de publication : 2009 Article en page(s) : pp. 4210–4215 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon dioxide Mutienzyme system Titania particles Biomimetic mineralization process Résumé : A green and efficient mutienzyme system was established, which efficiently converted carbon dioxide into methanol, by encapsulating three dehydrogenases within titania particles through a facile and mild biomimetic mineralization process. The enzyme-containing titania particles were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results indicated that the enzyme-containing titania particles were amorphous and consisted of interconnected nanospheres with sizes in the range of 400−600 nm. The three encapsulated dehydrogenases (formate dehydrogenase, formaldehyde dehydrogenase, alcohol dehydrogenase) sequentially converted carbon dioxide into HCOOH, CHOH, and CH3OH using NADH as a terminal electron donor for each dehydrogenase-catalyzed reduction. Compared to the open-style system which directly performed the bioconversion using free enzymes in aqueous solution, higher reaction yield in a wider pH and temperature range was obtained by the closed-style coimmobilization multienzyme system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801931j
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4210–4215[article] Green and efficient conversion of CO2 to methanol by biomimetic coimmobilization of three dehydrogenases in protamine-templated titania [texte imprimé] / Qianyun Sun, Auteur ; Yanjun Jiang, Auteur ; Zhongyi Jiang, Auteur . - 2009 . - pp. 4210–4215.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4210–4215
Mots-clés : Carbon dioxide Mutienzyme system Titania particles Biomimetic mineralization process Résumé : A green and efficient mutienzyme system was established, which efficiently converted carbon dioxide into methanol, by encapsulating three dehydrogenases within titania particles through a facile and mild biomimetic mineralization process. The enzyme-containing titania particles were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results indicated that the enzyme-containing titania particles were amorphous and consisted of interconnected nanospheres with sizes in the range of 400−600 nm. The three encapsulated dehydrogenases (formate dehydrogenase, formaldehyde dehydrogenase, alcohol dehydrogenase) sequentially converted carbon dioxide into HCOOH, CHOH, and CH3OH using NADH as a terminal electron donor for each dehydrogenase-catalyzed reduction. Compared to the open-style system which directly performed the bioconversion using free enzymes in aqueous solution, higher reaction yield in a wider pH and temperature range was obtained by the closed-style coimmobilization multienzyme system. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801931j Exemplaires
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Titre : Development of unified correlations for volumetric mass-transfer coefficient and effective interfacial area in bubble column reactors for various gas-liquid systems using support vector regression Type de document : texte imprimé Auteurs : Ankit B. Gandhi, Auteur ; Prashant P. Gupta, Auteur ; Jyeshtharaj B. Joshi, Auteur Année de publication : 2009 Article en page(s) : pp. 4216–4236 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Volumetric mass-transfer coefficient Unified correlation Bubble columns Gas− liquid systems Résumé : The objective of this study was to develop a unified correlation for the volumetric mass-transfer coefficient (kLa) and effective interfacial area (a) in bubble columns for various gas−liquid systems using support vector regression (SVR-) based modeling technique. From the data published in the open literature, 1600 data points from 27 open sources spanning the years 1965−2007 for kLa and 1330 data points from 28 open sources spanning the years 1968−2007 for a were collected. Generalized SVR-based models were developed for the relationship between kLa (and a) and each design and operating parameters such as column and sparger geometry, gas−liquid physical properties, operating temperature, pressure, superficial gas velocity, and so on. Further, these models for kLa and a are available online at http://www.esnips.com/web/UICT-NCL. The proposed generalized SVR-based correlations for kLa and a have prediction accuracies of 99.08% and 98.6% and average absolute relative errors (AAREs) of 7.12% and 5.01%, respectively. Also, the SVR-based correlation provided much improved predictions compared to those obtained using empirical correlations from the literature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003489
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4216–4236[article] Development of unified correlations for volumetric mass-transfer coefficient and effective interfacial area in bubble column reactors for various gas-liquid systems using support vector regression [texte imprimé] / Ankit B. Gandhi, Auteur ; Prashant P. Gupta, Auteur ; Jyeshtharaj B. Joshi, Auteur . - 2009 . - pp. 4216–4236.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4216–4236
Mots-clés : Volumetric mass-transfer coefficient Unified correlation Bubble columns Gas− liquid systems Résumé : The objective of this study was to develop a unified correlation for the volumetric mass-transfer coefficient (kLa) and effective interfacial area (a) in bubble columns for various gas−liquid systems using support vector regression (SVR-) based modeling technique. From the data published in the open literature, 1600 data points from 27 open sources spanning the years 1965−2007 for kLa and 1330 data points from 28 open sources spanning the years 1968−2007 for a were collected. Generalized SVR-based models were developed for the relationship between kLa (and a) and each design and operating parameters such as column and sparger geometry, gas−liquid physical properties, operating temperature, pressure, superficial gas velocity, and so on. Further, these models for kLa and a are available online at http://www.esnips.com/web/UICT-NCL. The proposed generalized SVR-based correlations for kLa and a have prediction accuracies of 99.08% and 98.6% and average absolute relative errors (AAREs) of 7.12% and 5.01%, respectively. Also, the SVR-based correlation provided much improved predictions compared to those obtained using empirical correlations from the literature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8003489 Exemplaires
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Titre : Degradation of surfactants by an integrated nanobubbles/VUV irradiation technique Type de document : texte imprimé Auteurs : Tsutomu Tasaki, Auteur ; Tsubasa Wada, Auteur ; Yoshinari Baba, Auteur Année de publication : 2009 Article en page(s) : pp. 4237–4244 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Water treatment Wastewater technique Nanobubbles Sodium dodecylbenzenesulfonate Résumé : Recently, many efforts have been devoted to the elimination of alkylbenzene sulfonate (ABS) surfactants from aqueous systems. In this paper, a water and wastewater treatment technique that uses an 8-W low-pressure mercury lamp in the presence of nanobubbles (diameter = 720 nm) was demonstrated for the decomposition of sodium dodecylbenzenesulfonate (SDBS), as a model compound in aqueous solution. Degradation experiments were conducted with an ozone lamp (185−254 nm), both with and without nanobubbles. The result shows that the oxidation and mineralization rate of SDBS were significantly enhanced under 185−254 nm irradiation by oxygen nanobubbles. Although a high concentration of surfactant was used in this study, SDBS removal is effective in the integrated nanobubbles/vacuum ultraviolet (VUV) system, via the observation of 99.8% SDBS oxidation and 76.8% total organic compound (TOC) removal after 24 h of irradiation. The current study investigates the effect of size of bubble on the mineralization rate of SDBS. Furthermore, the rates of surfactant degradation were compared with those of nonsurfactant such as benzene sulfonate (BS). It was found that the mineralization of SDBS surfactants with nanobubbles was observed to be more effective than that with microbubbles (diameter = 75.8 μm). The comparative results show that the mineralization rate of surfactants was much faster than nonsurfactant in the presence of nanobubles under 185−254 nm irradiation. Based on the experimental results and kinetic degradation model, we concluded that the enhancement on the mineralization of surfactants is attributed to the high adsorption capability of nanobubbles, because of the small particle size offering a large surface area to facilitate the reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801279b
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4237–4244[article] Degradation of surfactants by an integrated nanobubbles/VUV irradiation technique [texte imprimé] / Tsutomu Tasaki, Auteur ; Tsubasa Wada, Auteur ; Yoshinari Baba, Auteur . - 2009 . - pp. 4237–4244.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4237–4244
Mots-clés : Water treatment Wastewater technique Nanobubbles Sodium dodecylbenzenesulfonate Résumé : Recently, many efforts have been devoted to the elimination of alkylbenzene sulfonate (ABS) surfactants from aqueous systems. In this paper, a water and wastewater treatment technique that uses an 8-W low-pressure mercury lamp in the presence of nanobubbles (diameter = 720 nm) was demonstrated for the decomposition of sodium dodecylbenzenesulfonate (SDBS), as a model compound in aqueous solution. Degradation experiments were conducted with an ozone lamp (185−254 nm), both with and without nanobubbles. The result shows that the oxidation and mineralization rate of SDBS were significantly enhanced under 185−254 nm irradiation by oxygen nanobubbles. Although a high concentration of surfactant was used in this study, SDBS removal is effective in the integrated nanobubbles/vacuum ultraviolet (VUV) system, via the observation of 99.8% SDBS oxidation and 76.8% total organic compound (TOC) removal after 24 h of irradiation. The current study investigates the effect of size of bubble on the mineralization rate of SDBS. Furthermore, the rates of surfactant degradation were compared with those of nonsurfactant such as benzene sulfonate (BS). It was found that the mineralization of SDBS surfactants with nanobubbles was observed to be more effective than that with microbubbles (diameter = 75.8 μm). The comparative results show that the mineralization rate of surfactants was much faster than nonsurfactant in the presence of nanobubles under 185−254 nm irradiation. Based on the experimental results and kinetic degradation model, we concluded that the enhancement on the mineralization of surfactants is attributed to the high adsorption capability of nanobubbles, because of the small particle size offering a large surface area to facilitate the reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801279b Exemplaires
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Titre : Design of copolymer molecular architecture via design of continuous reactor systems for controlled radical polymerization Type de document : texte imprimé Auteurs : Amin Zargar, Auteur ; F. Joseph Schork, Auteur Année de publication : 2009 Article en page(s) : pp. 4245–4253 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continuous reactor trains Polydispersity Copolymer Résumé : In controlled radical polymerizations, the lifetime of a growing chain is approximately the residence time in the reactor train. Under these conditions, it is possible to use various continuous reactor trains (CSTRs and PFRs in series) to manipulate the molecular architecture. This work illustrates the design, by iterative simulation, of continuous reactor trains to produce highly specific molecular architectures. In addition to determining the typical parameters of polydispersity, molecular weight, and copolymer composition, the simulation produces information about the sequence structure in the copolymer. Prior work has shown the ability to use moment equations to analyze the sequence structure of batch polymerization and the potential to vary batch reactor conditions to produce copolymers with different sequences from the head to the tail of the copolymer. This work extends the technique of sequence distribution analysis through population balances to continuous reactor trains molecular architectures with specific molecular weight, copolymer composition, and sequence distribution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801422w
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4245–4253[article] Design of copolymer molecular architecture via design of continuous reactor systems for controlled radical polymerization [texte imprimé] / Amin Zargar, Auteur ; F. Joseph Schork, Auteur . - 2009 . - pp. 4245–4253.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4245–4253
Mots-clés : Continuous reactor trains Polydispersity Copolymer Résumé : In controlled radical polymerizations, the lifetime of a growing chain is approximately the residence time in the reactor train. Under these conditions, it is possible to use various continuous reactor trains (CSTRs and PFRs in series) to manipulate the molecular architecture. This work illustrates the design, by iterative simulation, of continuous reactor trains to produce highly specific molecular architectures. In addition to determining the typical parameters of polydispersity, molecular weight, and copolymer composition, the simulation produces information about the sequence structure in the copolymer. Prior work has shown the ability to use moment equations to analyze the sequence structure of batch polymerization and the potential to vary batch reactor conditions to produce copolymers with different sequences from the head to the tail of the copolymer. This work extends the technique of sequence distribution analysis through population balances to continuous reactor trains molecular architectures with specific molecular weight, copolymer composition, and sequence distribution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801422w Exemplaires
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Titre : Understanding biphasic ionic liquid/CO2 systems for homogeneous catalysis : hydroformylation Type de document : texte imprimé Auteurs : Azita Ahosseini, Auteur ; Wei Ren, Auteur ; Aaron M. Scurto, Auteur Année de publication : 2009 Article en page(s) : pp. 4254–4265 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Biphasic ionic liquid Compressed carbon dioxide system Homogeneous catalysis Hydroformylation Résumé : A biphasic ionic liquid (IL) and compressed carbon dioxide system has a number of advantages for efficient homogeneous catalysis. The hydroformylation of 1-octene to nonanal catalyzed by a rhodium−triphenylphosphine complex was used as a model reaction to illustrate the effects of carbon dioxide in a biphasic ionic liquid/CO2 system using the model ionic liquid, 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ([HMIm][Tf2N]). Detailed phase equilibrium studies were conducted to determine volume expansion of the IL phase and the multiphase equilibria and mixture critical points between the reactant, product, and IL with CO2 and syngas (CO/H2). These data ultimately affect the concentration of the reactant and, thus, the apparent reaction rate. The viscosity of the IL with CO2 pressure was measured and demonstrates the dramatic decrease with increasing CO2 pressure. The self-diffusion coefficient of the ionic liquid and 1-octene were measured and indicate a large increase with CO2 pressure (solubility). With an understanding of the kinetics, phase behavior, and mass transport, biphasic IL/CO2 reaction systems may be properly understood and designed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801871k
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4254–4265[article] Understanding biphasic ionic liquid/CO2 systems for homogeneous catalysis : hydroformylation [texte imprimé] / Azita Ahosseini, Auteur ; Wei Ren, Auteur ; Aaron M. Scurto, Auteur . - 2009 . - pp. 4254–4265.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4254–4265
Mots-clés : Biphasic ionic liquid Compressed carbon dioxide system Homogeneous catalysis Hydroformylation Résumé : A biphasic ionic liquid (IL) and compressed carbon dioxide system has a number of advantages for efficient homogeneous catalysis. The hydroformylation of 1-octene to nonanal catalyzed by a rhodium−triphenylphosphine complex was used as a model reaction to illustrate the effects of carbon dioxide in a biphasic ionic liquid/CO2 system using the model ionic liquid, 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ([HMIm][Tf2N]). Detailed phase equilibrium studies were conducted to determine volume expansion of the IL phase and the multiphase equilibria and mixture critical points between the reactant, product, and IL with CO2 and syngas (CO/H2). These data ultimately affect the concentration of the reactant and, thus, the apparent reaction rate. The viscosity of the IL with CO2 pressure was measured and demonstrates the dramatic decrease with increasing CO2 pressure. The self-diffusion coefficient of the ionic liquid and 1-octene were measured and indicate a large increase with CO2 pressure (solubility). With an understanding of the kinetics, phase behavior, and mass transport, biphasic IL/CO2 reaction systems may be properly understood and designed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801871k Exemplaires
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Titre : Catalytic effect of free fatty acids on cotton seed oil thermal transesterification Type de document : texte imprimé Auteurs : Stergios A. Pasias, Auteur ; Nikos K. Barakos, Auteur ; Nikos G. Papayannakos, Auteur Année de publication : 2009 Article en page(s) : pp. 4266–4273 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cotton seed oil Transesterification Methanol Résumé : The thermal transesterification of cottonseed oil with methanol has been investigated. Refined as well as cotton seed oil containing 9.8 wt. % free fatty acids (FFAs) were used. The impact of the free fatty acids present in the oil on the transesterification reaction rates has been studied. Free fatty acids were esterified in parallel with triglycerides (TGs) methanolysis reactions but their presence was beneficial for transesterification reactions as they appeared to have a catalytic effect on the monoglycerides (MGs), diglycerides (DGs), and triglycerides conversion reactions. Experiments were performed in a batch reactor in the temperature range of 170−220 °C and using a 6:1 methanol to oil molar ratio. A kinetic model describing the thermal transesterification and esterification reaction as well as the catalytic transesterification reactions by the FFAs is presented. The proposed kinetics might also be used in transesterification processes using solid catalysts in the same temperature range to estimate the net catalytic effects unmasked from thermal conversion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801365k
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4266–4273[article] Catalytic effect of free fatty acids on cotton seed oil thermal transesterification [texte imprimé] / Stergios A. Pasias, Auteur ; Nikos K. Barakos, Auteur ; Nikos G. Papayannakos, Auteur . - 2009 . - pp. 4266–4273.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4266–4273
Mots-clés : Cotton seed oil Transesterification Methanol Résumé : The thermal transesterification of cottonseed oil with methanol has been investigated. Refined as well as cotton seed oil containing 9.8 wt. % free fatty acids (FFAs) were used. The impact of the free fatty acids present in the oil on the transesterification reaction rates has been studied. Free fatty acids were esterified in parallel with triglycerides (TGs) methanolysis reactions but their presence was beneficial for transesterification reactions as they appeared to have a catalytic effect on the monoglycerides (MGs), diglycerides (DGs), and triglycerides conversion reactions. Experiments were performed in a batch reactor in the temperature range of 170−220 °C and using a 6:1 methanol to oil molar ratio. A kinetic model describing the thermal transesterification and esterification reaction as well as the catalytic transesterification reactions by the FFAs is presented. The proposed kinetics might also be used in transesterification processes using solid catalysts in the same temperature range to estimate the net catalytic effects unmasked from thermal conversion. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801365k Exemplaires
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Titre : Reduction of bisphenol A residue in polycarbonates in a two-stage step-growth polymerization process Type de document : texte imprimé Auteurs : Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur Année de publication : 2009 Article en page(s) : pp. 4274–4282 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polycondensation process Bisphenol A polycarbonate Résumé : A theoretical modeling and simulation study is presented for the design of operational policies for a two-stage polycondensation process to achieve a significant reduction of bisphenol A (BPA) residue in high molecular weight bisphenol A polycarbonate (BAPC). In the first stage, low molecular weight polycarbonate prepolymers are prepared in a semibatch melt transesterification reactor under reduced pressure, and in the second stage, a solid-state polymerization is used to further increase the polymer molecular weight and to reduce the BPA residue. The residual BPA concentration in the final polymer can be significantly reduced by employing an optimally determined excess amount of diphenyl carbonate (DPC) in the transesterification stage. However, there is a narrow window of operating conditions that will satisfy the multiple process requirements of the lowest BPA concentration, high molecular weight, and economically feasible short reaction time. The proposed method can also be applied to optimally blending prepolymers of different reactive end group concentrations for the subsequent solid-state polymerization to reduce the BPA content and to obtain high molecular weight. The proposed methods are illustrated through model simulations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014318
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4274–4282[article] Reduction of bisphenol A residue in polycarbonates in a two-stage step-growth polymerization process [texte imprimé] / Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur . - 2009 . - pp. 4274–4282.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4274–4282
Mots-clés : Polycondensation process Bisphenol A polycarbonate Résumé : A theoretical modeling and simulation study is presented for the design of operational policies for a two-stage polycondensation process to achieve a significant reduction of bisphenol A (BPA) residue in high molecular weight bisphenol A polycarbonate (BAPC). In the first stage, low molecular weight polycarbonate prepolymers are prepared in a semibatch melt transesterification reactor under reduced pressure, and in the second stage, a solid-state polymerization is used to further increase the polymer molecular weight and to reduce the BPA residue. The residual BPA concentration in the final polymer can be significantly reduced by employing an optimally determined excess amount of diphenyl carbonate (DPC) in the transesterification stage. However, there is a narrow window of operating conditions that will satisfy the multiple process requirements of the lowest BPA concentration, high molecular weight, and economically feasible short reaction time. The proposed method can also be applied to optimally blending prepolymers of different reactive end group concentrations for the subsequent solid-state polymerization to reduce the BPA content and to obtain high molecular weight. The proposed methods are illustrated through model simulations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014318 Exemplaires
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Titre : Hydrodesulfurization activity of NiMo/Al-HMS nanocatalyst synthesized by supercritical impregnation Type de document : texte imprimé Auteurs : Mehrdad Alibouri, Auteur ; Seyyed M. Ghoreishi, Auteur ; Hamid R. Aghabozorg, Auteur Année de publication : 2009 Article en page(s) : pp. 4283–4292 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : NiMo/Al-HMS nanocatalyst CO2-methanol deposition Wet coimpregnation Hydrodesulfurization Résumé : The synthesis of NiMo/Al-HMS nanocatalyst (2.3 wt % Ni and 9.4 wt % Mo) via supercritical CO2−methanol deposition and conventional wet coimpregnation was investigated. The characterization of both catalysts by adsorption−desorption of nitrogen, oxygen chemisorptions, XRD, TPR, and TEM indicated that Ni and Mo highly and uniformly dispersed on the Al-HMS support. The results of activity of the NiMo/Al-HMS nanocatalyst in the hydrodesulfurization of dibenzothiophene demonstrated higher conversion for the NiMo/Al-HMS nanocatalyst in contrast to conventional catalyst. The reaction rate constants at 330 °C for the NiMo/Al-HMS nanocatalyst and the conventional one were calculated to be 3.65 × 10−5 and 2.20 × 10−5 (mol /g cat. min), respectively. Moreover, the newly developed nanocatalyst is less inhibited than the conventional catalyst by aromatics such as toluene. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801442c
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4283–4292[article] Hydrodesulfurization activity of NiMo/Al-HMS nanocatalyst synthesized by supercritical impregnation [texte imprimé] / Mehrdad Alibouri, Auteur ; Seyyed M. Ghoreishi, Auteur ; Hamid R. Aghabozorg, Auteur . - 2009 . - pp. 4283–4292.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4283–4292
Mots-clés : NiMo/Al-HMS nanocatalyst CO2-methanol deposition Wet coimpregnation Hydrodesulfurization Résumé : The synthesis of NiMo/Al-HMS nanocatalyst (2.3 wt % Ni and 9.4 wt % Mo) via supercritical CO2−methanol deposition and conventional wet coimpregnation was investigated. The characterization of both catalysts by adsorption−desorption of nitrogen, oxygen chemisorptions, XRD, TPR, and TEM indicated that Ni and Mo highly and uniformly dispersed on the Al-HMS support. The results of activity of the NiMo/Al-HMS nanocatalyst in the hydrodesulfurization of dibenzothiophene demonstrated higher conversion for the NiMo/Al-HMS nanocatalyst in contrast to conventional catalyst. The reaction rate constants at 330 °C for the NiMo/Al-HMS nanocatalyst and the conventional one were calculated to be 3.65 × 10−5 and 2.20 × 10−5 (mol /g cat. min), respectively. Moreover, the newly developed nanocatalyst is less inhibited than the conventional catalyst by aromatics such as toluene. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801442c Exemplaires
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Titre : Silicalite-1 zeolite membrane reactor packed with HZSM-5 catalyst for meta-xylene isomerization Type de document : texte imprimé Auteurs : Chun Zhang, Auteur ; Zhou Hong, Auteur ; Xuehong Gu, Auteur Année de publication : 2009 Article en page(s) : pp. 4293–4299 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Silicalite-1 zeolite membrane Para-xylene selectivity Meta-xylene Isomerization Résumé : A silicalite-1/α-Al2O3 zeolite membrane with high para-xylene (PX) selectivity was tested for isomerization of meta-xylene (MX) to PX. Two HZSM-5 catalyst packing methods were compared in the membrane reactor: (1) catalyst in contact with the Al2O3 substrate and (2) catalyst in contact with the membrane layer. The second packing method exhibited higher efficiency for MX isomerization. Compared with a conventional reactor, the membrane reactor with the second catalyst packing method had increased rates of 26.0% and 31.2% for the PX yield and selectivity, respectively, at a temperature of 270 °C. PX selectivity and yield increased as the flow rate of the sweep gas increased because of the enhanced PX flux through the zeolite membrane. Increasing the gas hourly space velocity (GHSV) could reduce the contribution of membrane permeation to PX productivity. It was also revealed that MFI zeolite membranes exhibit a high stability for xylene isomerization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801606s
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4293–4299[article] Silicalite-1 zeolite membrane reactor packed with HZSM-5 catalyst for meta-xylene isomerization [texte imprimé] / Chun Zhang, Auteur ; Zhou Hong, Auteur ; Xuehong Gu, Auteur . - 2009 . - pp. 4293–4299.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4293–4299
Mots-clés : Silicalite-1 zeolite membrane Para-xylene selectivity Meta-xylene Isomerization Résumé : A silicalite-1/α-Al2O3 zeolite membrane with high para-xylene (PX) selectivity was tested for isomerization of meta-xylene (MX) to PX. Two HZSM-5 catalyst packing methods were compared in the membrane reactor: (1) catalyst in contact with the Al2O3 substrate and (2) catalyst in contact with the membrane layer. The second packing method exhibited higher efficiency for MX isomerization. Compared with a conventional reactor, the membrane reactor with the second catalyst packing method had increased rates of 26.0% and 31.2% for the PX yield and selectivity, respectively, at a temperature of 270 °C. PX selectivity and yield increased as the flow rate of the sweep gas increased because of the enhanced PX flux through the zeolite membrane. Increasing the gas hourly space velocity (GHSV) could reduce the contribution of membrane permeation to PX productivity. It was also revealed that MFI zeolite membranes exhibit a high stability for xylene isomerization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801606s Exemplaires
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Titre : Kinetics of aqueous phase dehydration of xylose into furfural catalyzed by ZSM-5 zeolite Type de document : texte imprimé Auteurs : Rebecca O’Neill, Auteur ; Mohammad Najeeb Ahmad, Auteur ; Laurent Vanoye, Auteur Année de publication : 2009 Article en page(s) : pp. 4300–4306 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Xylose Aqueous phase dehydration ZSM-5 zeolite Résumé : ZSM-5 zeolite in H+ form with an average pore size of 1.2 nm was used for aqueous phase dehydration of xylose to furfural at low temperatures; that is, from 413 to 493 K. The selectivity in furfural increased with the temperature to a value of 473 K. Beyond this temperature, condensation reactions were significant and facilitated by the intrinsic structure of ZSM-5. A reaction mechanism that included isomerization of xylose to lyxose, dehydration of lyxose and xylose to furfural, fragmentation of furfural to organic acids, oligomerization of furfural to bi- and tridimensional furilic species, and complete dehydration of organic acids to carbonaceous deposits was developed, and the associated kinetic parameters were estimated. The rate of furfural production was found to be more sensitive to temperature than the rates of side reactions, with an estimated activation energy of 32.1 kcal/mol. This value correlated well with data in the literature obtained by homogeneous catalytic dehydration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801599k
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4300–4306[article] Kinetics of aqueous phase dehydration of xylose into furfural catalyzed by ZSM-5 zeolite [texte imprimé] / Rebecca O’Neill, Auteur ; Mohammad Najeeb Ahmad, Auteur ; Laurent Vanoye, Auteur . - 2009 . - pp. 4300–4306.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4300–4306
Mots-clés : Xylose Aqueous phase dehydration ZSM-5 zeolite Résumé : ZSM-5 zeolite in H+ form with an average pore size of 1.2 nm was used for aqueous phase dehydration of xylose to furfural at low temperatures; that is, from 413 to 493 K. The selectivity in furfural increased with the temperature to a value of 473 K. Beyond this temperature, condensation reactions were significant and facilitated by the intrinsic structure of ZSM-5. A reaction mechanism that included isomerization of xylose to lyxose, dehydration of lyxose and xylose to furfural, fragmentation of furfural to organic acids, oligomerization of furfural to bi- and tridimensional furilic species, and complete dehydration of organic acids to carbonaceous deposits was developed, and the associated kinetic parameters were estimated. The rate of furfural production was found to be more sensitive to temperature than the rates of side reactions, with an estimated activation energy of 32.1 kcal/mol. This value correlated well with data in the literature obtained by homogeneous catalytic dehydration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801599k Exemplaires
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Titre : Mechanism and kinetics of sulfite oxidation in the presence of ethanol Type de document : texte imprimé Auteurs : Li-Dong Wang, Auteur ; Yong-Liang Ma, Auteur ; Ji-Ming Hao, Auteur Année de publication : 2009 Article en page(s) : pp. 4307–4311 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Sulfite oxidation Ethanol Oxidation kinetics Résumé : Oxidation of sulfite is an important process in flue gas desulfurization. The inhibitory effects of four inhibitors on the intrinsic oxidation of sulfite were compared, and ethanol was found to be an excellent inhibitor. The intrinsic oxidation kinetics of sulfite in the presence of ethanol used as an inhibitor was investigated using a batch apparatus. The reaction orders of the reagents and the activation energy were obtained. The results indicate that the intrinsic reaction proceeds in two steps: rapid reaction in an oxygen-rich state and slow reaction in an oxygen-depleted state. Integrated with the macroscopic oxidation kinetics of calcium sulfite in the presence of an ethanol inhibitor, it was concluded that the macroscopic oxidation process is controlled by the intrinsic reaction rate and the intrinsic oxidation reaction proceeds in the rapid reaction state. Furthermore, a mechanism for the intrinsic reaction is proposed based on a steady-state assumption. The results derived with this mechanism are in good agreement with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801731h
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4307–4311[article] Mechanism and kinetics of sulfite oxidation in the presence of ethanol [texte imprimé] / Li-Dong Wang, Auteur ; Yong-Liang Ma, Auteur ; Ji-Ming Hao, Auteur . - 2009 . - pp. 4307–4311.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4307–4311
Mots-clés : Sulfite oxidation Ethanol Oxidation kinetics Résumé : Oxidation of sulfite is an important process in flue gas desulfurization. The inhibitory effects of four inhibitors on the intrinsic oxidation of sulfite were compared, and ethanol was found to be an excellent inhibitor. The intrinsic oxidation kinetics of sulfite in the presence of ethanol used as an inhibitor was investigated using a batch apparatus. The reaction orders of the reagents and the activation energy were obtained. The results indicate that the intrinsic reaction proceeds in two steps: rapid reaction in an oxygen-rich state and slow reaction in an oxygen-depleted state. Integrated with the macroscopic oxidation kinetics of calcium sulfite in the presence of an ethanol inhibitor, it was concluded that the macroscopic oxidation process is controlled by the intrinsic reaction rate and the intrinsic oxidation reaction proceeds in the rapid reaction state. Furthermore, a mechanism for the intrinsic reaction is proposed based on a steady-state assumption. The results derived with this mechanism are in good agreement with the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801731h Exemplaires
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Titre : Dissolution and diffusion of oxygen in deaerated water and escape of oxygen to the atmosphere from an oxygen saturated aqueous solution : an investigation by a pulse radiolysis technique Type de document : texte imprimé Auteurs : Surajdevprakash B. Dhiman, Auteur ; Devidas B. Naik, Auteur Année de publication : 2009 Article en page(s) : pp. 4312–4315 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oxygen diffusion dissolution Hydrated electrons Pulse radiolysis technique Résumé : Fast reaction of hydrated electrons (eaq−) with oxygen has been used to determine the dissolution and diffusion of oxygen in water by monitoring the decay of eaq− at 700 nm. Hydrated electrons in the irradiated volume (7.5 cm below the surface) were generated by pulse radiolysis technique. Water was purged with high purity nitrogen to remove dissolved oxygen, and subsequently, the lifetime of the eaq− formed on pulse radiolysis was determined at various times after exposure to atmosphere. The lifetime of the eaq− measured in the irradiated volume was negligibly affected until ∼60 min after the water was exposed to atmosphere. Then onward, the lifetime of eaq− decreased as a result of oxygen reaching the irradiated volume. In another set of experiments, reaction of methyl viologen radical cations (generated by the reaction of eaq− with methyl viologen) with oxygen (k = 4.3 × 108 dm3 mol−1 s−1) was investigated to find out how the dissolved oxygen escapes from oxygen-saturated solution to the atmosphere by observing the increase in the lifetime of methyl viologen radical cations. In 140 min, concentration of oxygen comes down to the value present in the ambient aerated solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801928u
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4312–4315[article] Dissolution and diffusion of oxygen in deaerated water and escape of oxygen to the atmosphere from an oxygen saturated aqueous solution : an investigation by a pulse radiolysis technique [texte imprimé] / Surajdevprakash B. Dhiman, Auteur ; Devidas B. Naik, Auteur . - 2009 . - pp. 4312–4315.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4312–4315
Mots-clés : Oxygen diffusion dissolution Hydrated electrons Pulse radiolysis technique Résumé : Fast reaction of hydrated electrons (eaq−) with oxygen has been used to determine the dissolution and diffusion of oxygen in water by monitoring the decay of eaq− at 700 nm. Hydrated electrons in the irradiated volume (7.5 cm below the surface) were generated by pulse radiolysis technique. Water was purged with high purity nitrogen to remove dissolved oxygen, and subsequently, the lifetime of the eaq− formed on pulse radiolysis was determined at various times after exposure to atmosphere. The lifetime of the eaq− measured in the irradiated volume was negligibly affected until ∼60 min after the water was exposed to atmosphere. Then onward, the lifetime of eaq− decreased as a result of oxygen reaching the irradiated volume. In another set of experiments, reaction of methyl viologen radical cations (generated by the reaction of eaq− with methyl viologen) with oxygen (k = 4.3 × 108 dm3 mol−1 s−1) was investigated to find out how the dissolved oxygen escapes from oxygen-saturated solution to the atmosphere by observing the increase in the lifetime of methyl viologen radical cations. In 140 min, concentration of oxygen comes down to the value present in the ambient aerated solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801928u Exemplaires
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Titre : A rapid hot-injection method for the improved hydrothermal synthesis of CdSe nanoparticles Type de document : texte imprimé Auteurs : Juandria V. Williams, Auteur ; Nicholas A. Kotov, Auteur ; Phillip E. Savage, Auteur Année de publication : 2009 Article en page(s) : pp. 4316–4321 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cadmium selenide Hot-injection method Organic solvents Résumé : Cadmium selenide (CdSe) quantum dots were prepared in high-temperature water via a rapid hot-injection method intended to mimic conventional synthesis in organic solvents. The nanocrystals were smaller than those previously produced hydrothermally under nonisothermal conditions when using the same process parameters. It is possible that the nucleation and growth events were greatly influenced by the present injection method. In general, the physical and optical properties of the nanocrystals were influenced by the experimental conditions. Variations in reaction temperature (200−240 °C), reaction time (1−10 min), pH (7−11), Cd:Se molar ratio (4:1−40:1) and Cd:stabilizer molar ratio (0.24−1.18) affected the mean particle size, distribution of sizes, and quantum yield. As-prepared nanoparticles exhibited quantum yields in excess of 5%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007067
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4316–4321[article] A rapid hot-injection method for the improved hydrothermal synthesis of CdSe nanoparticles [texte imprimé] / Juandria V. Williams, Auteur ; Nicholas A. Kotov, Auteur ; Phillip E. Savage, Auteur . - 2009 . - pp. 4316–4321.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4316–4321
Mots-clés : Cadmium selenide Hot-injection method Organic solvents Résumé : Cadmium selenide (CdSe) quantum dots were prepared in high-temperature water via a rapid hot-injection method intended to mimic conventional synthesis in organic solvents. The nanocrystals were smaller than those previously produced hydrothermally under nonisothermal conditions when using the same process parameters. It is possible that the nucleation and growth events were greatly influenced by the present injection method. In general, the physical and optical properties of the nanocrystals were influenced by the experimental conditions. Variations in reaction temperature (200−240 °C), reaction time (1−10 min), pH (7−11), Cd:Se molar ratio (4:1−40:1) and Cd:stabilizer molar ratio (0.24−1.18) affected the mean particle size, distribution of sizes, and quantum yield. As-prepared nanoparticles exhibited quantum yields in excess of 5%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007067 Exemplaires
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Titre : Scanning electron microscopy measurements of the surface roughness of paper Type de document : texte imprimé Auteurs : Sujit Banerjee, Auteur ; Yang, Rallming, Auteur ; Charles E. Courchene, Auteur Année de publication : 2009 Article en page(s) : pp. 4322–4325 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Paper sheet X-y uniformity Roughness Scanning electron microscopy Résumé : A new approach to the measurement of x−y uniformity of the surface of a paper sheet is described. Scanning electron micrographs are taken of both the top and bottom surfaces of a paper sheet and image-analyzed. The images were converted to grayscale, and the standard deviation of the pixel brightness was called the “SEM roughness index” and calculated for each surface. Both commercial newsprint sheets and handsheets made with kraft, TMP, and recycled fibers were examined. Debonders and cationic polymers were added to some sheets. The addition of debonders increases the index on the top side of the sheet but decreases it on the bottom. This is caused by the movement of fines from the top to the bottom side. The addition of cationic polymers increases the SEM roughness index by increasing the degree of microfloc formation. Samples taken across a reel from a commercial paper machine tend to show a mirror image relationship between the top and bottom surfaces. The SEM roughness index is able to detect subtle changes in sheet structure caused by differences in the mode of addition of polymers used for retaining fines in the sheet. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900029v
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4322–4325[article] Scanning electron microscopy measurements of the surface roughness of paper [texte imprimé] / Sujit Banerjee, Auteur ; Yang, Rallming, Auteur ; Charles E. Courchene, Auteur . - 2009 . - pp. 4322–4325.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4322–4325
Mots-clés : Paper sheet X-y uniformity Roughness Scanning electron microscopy Résumé : A new approach to the measurement of x−y uniformity of the surface of a paper sheet is described. Scanning electron micrographs are taken of both the top and bottom surfaces of a paper sheet and image-analyzed. The images were converted to grayscale, and the standard deviation of the pixel brightness was called the “SEM roughness index” and calculated for each surface. Both commercial newsprint sheets and handsheets made with kraft, TMP, and recycled fibers were examined. Debonders and cationic polymers were added to some sheets. The addition of debonders increases the index on the top side of the sheet but decreases it on the bottom. This is caused by the movement of fines from the top to the bottom side. The addition of cationic polymers increases the SEM roughness index by increasing the degree of microfloc formation. Samples taken across a reel from a commercial paper machine tend to show a mirror image relationship between the top and bottom surfaces. The SEM roughness index is able to detect subtle changes in sheet structure caused by differences in the mode of addition of polymers used for retaining fines in the sheet. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900029v Exemplaires
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Titre : Inorganic−organic nanocomposite based hard coatings on plastics using in situ generated nano-SiO2 bonded with ≡Si—O—Si—PEO hybrid network Type de document : texte imprimé Auteurs : Samar Kumar Medda, Auteur ; Goutam De, Auteur Année de publication : 2009 Article en page(s) : pp. 4326–4333 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Inorganic-organic hybrid nanocomposite Tetraethyl orthosilicate Hydrolysis− condensation reactions Résumé : Inorganic−organic hybrid nanocomposite sols were prepared using tetraethyl orthosilicate (TEOS), 3-(glycidoxypropyl)trimethoxysilane (GLYMO), n-butanol, water, methanol, and catalytic amounts of HCl and Al(acac)3. Hydrolysis−condensation reactions of TEOS at pH ≈ 1.3 generates silica nanoparticles in the sol that remain bonded with the −Si−O−Si− network and protected by the organic functionality of GLYMO. The pH of the final sol was adjusted to close to the isoelectric point of silica (pH ∼ 2) to increase the shelf life of the sol. The resulting sol (obtained from the best optimized composition TEOS:GLYMO = 2.33:1) when deposited on CR-39 or related plastics yielded optically transparent and spot-free hard coatings after thermal curing at 95 °C. About 1.5−2 μm thick coatings serve all international specifications required for hard coatings. Thermal curing in the presence of Al(acac)3 ensured polymerization of GLYMO originated epoxy groups to polyethylene oxide (PEO). BET surface area measurement confirms that the cured coatings are nonporous (surface area 0.6−0.8 m2 g−1) in nature. The density of the coating was measured by the X-ray reflectivity technique (XRR) and found to be 1.70 g cm−3. TEM shows flaky plastic-like characteristics of the coatings, and small-angle X-ray scattering (SAXS) study reveals the presence SiO2 nanoparticles of average size 5.4 nm inside the coatings. The pencil hardness value of the coatings (thickness 1.5−2 μm) was >6H. The high hardness of these nanocomposite coatings is mainly due to the in situ generated silica nanoparticles chemically bonded with the highly cross-linked silica−PEO network. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801632k
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4326–4333[article] Inorganic−organic nanocomposite based hard coatings on plastics using in situ generated nano-SiO2 bonded with ≡Si—O—Si—PEO hybrid network [texte imprimé] / Samar Kumar Medda, Auteur ; Goutam De, Auteur . - 2009 . - pp. 4326–4333.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4326–4333
Mots-clés : Inorganic-organic hybrid nanocomposite Tetraethyl orthosilicate Hydrolysis− condensation reactions Résumé : Inorganic−organic hybrid nanocomposite sols were prepared using tetraethyl orthosilicate (TEOS), 3-(glycidoxypropyl)trimethoxysilane (GLYMO), n-butanol, water, methanol, and catalytic amounts of HCl and Al(acac)3. Hydrolysis−condensation reactions of TEOS at pH ≈ 1.3 generates silica nanoparticles in the sol that remain bonded with the −Si−O−Si− network and protected by the organic functionality of GLYMO. The pH of the final sol was adjusted to close to the isoelectric point of silica (pH ∼ 2) to increase the shelf life of the sol. The resulting sol (obtained from the best optimized composition TEOS:GLYMO = 2.33:1) when deposited on CR-39 or related plastics yielded optically transparent and spot-free hard coatings after thermal curing at 95 °C. About 1.5−2 μm thick coatings serve all international specifications required for hard coatings. Thermal curing in the presence of Al(acac)3 ensured polymerization of GLYMO originated epoxy groups to polyethylene oxide (PEO). BET surface area measurement confirms that the cured coatings are nonporous (surface area 0.6−0.8 m2 g−1) in nature. The density of the coating was measured by the X-ray reflectivity technique (XRR) and found to be 1.70 g cm−3. TEM shows flaky plastic-like characteristics of the coatings, and small-angle X-ray scattering (SAXS) study reveals the presence SiO2 nanoparticles of average size 5.4 nm inside the coatings. The pencil hardness value of the coatings (thickness 1.5−2 μm) was >6H. The high hardness of these nanocomposite coatings is mainly due to the in situ generated silica nanoparticles chemically bonded with the highly cross-linked silica−PEO network. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801632k Exemplaires
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Titre : Hydrothermal synthesis of titanium silicalite-1 structurally directed by hexamethyleneimine Type de document : texte imprimé Auteurs : Haijiao Zhang, Auteur ; Yueming Liu, Auteur ; Zheng Jiao, Auteur Année de publication : 2009 Article en page(s) : pp. 4334–4339 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Titanium silicalite-1 Hexamethyleneimine Active seeds Résumé : Titanium silicalite-1 (TS-1) with the MFI topology has been synthesized successfully in the absence of alkali metal ions with the cooperative effects of active seeds and the structure-directing agent hexamethyleneimine (HMI). The physicochemical properties and structures of the products were characterized by various techniques. The coexistence of HMI and primary and/or secondary building units of the MFI structure in the synthesitic gels was essential for the nucleation and crystallization of TS-1. The nature and preparation conditions of the seed precursors had a great influence on the crystallization process and the incorporation of titanium atoms into the framework. It was found that a synergistic effect between HMI and the precursor seeds led to the full crystallization of TS-1. Other synthesis parameters such as boron addition, silicon source, and crystallization time were also investigated. Moreover, the present synthesis system is also applicable to the preparation of other MFI analogues. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016253
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4334–4339[article] Hydrothermal synthesis of titanium silicalite-1 structurally directed by hexamethyleneimine [texte imprimé] / Haijiao Zhang, Auteur ; Yueming Liu, Auteur ; Zheng Jiao, Auteur . - 2009 . - pp. 4334–4339.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4334–4339
Mots-clés : Titanium silicalite-1 Hexamethyleneimine Active seeds Résumé : Titanium silicalite-1 (TS-1) with the MFI topology has been synthesized successfully in the absence of alkali metal ions with the cooperative effects of active seeds and the structure-directing agent hexamethyleneimine (HMI). The physicochemical properties and structures of the products were characterized by various techniques. The coexistence of HMI and primary and/or secondary building units of the MFI structure in the synthesitic gels was essential for the nucleation and crystallization of TS-1. The nature and preparation conditions of the seed precursors had a great influence on the crystallization process and the incorporation of titanium atoms into the framework. It was found that a synergistic effect between HMI and the precursor seeds led to the full crystallization of TS-1. Other synthesis parameters such as boron addition, silicon source, and crystallization time were also investigated. Moreover, the present synthesis system is also applicable to the preparation of other MFI analogues. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016253 Exemplaires
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Titre : Effects of storage aging on the properties of epoxy prepregs Type de document : texte imprimé Auteurs : Yingfeng Yu, Auteur ; Huihuang Su, Auteur ; Wenjun Gan, Auteur Année de publication : 2009 Article en page(s) : pp. 4340–4345 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Epoxy prepregs Storage Fourier transform spectroscopies Dynamic mechanical analysis Rheological Time-resolved light scattering Optical microscopy Résumé : Changes in the properties of epoxy prepregs during storage are of both industrial and theoretical interest. It would be very helpful to have a test, suitable for production use, to determine when a prepreg has aged beyond acceptable limits. In this article, different epoxy prepregs aged under various conditions were studied by near-infrared (NIR) and mid-infrared (MIR) Fourier transform spectroscopies, dynamic mechanical analysis (DMA), rheological analysis, time-resolved light scattering (TRLS), and optical microscopy (OM). A very good relationship between storage aging time and curing conversion was obtained by NIR measurements. Furthermore, the rheological study showed that both the viscosity and the gelation time changed with storage aging. Changes in the glass transition temperatures of epoxy prepregs can result from either curing or phase separation during storage aging. The TRLS and OM results showed that structural evolution might occur during storage for some prepregs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018005
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4340–4345[article] Effects of storage aging on the properties of epoxy prepregs [texte imprimé] / Yingfeng Yu, Auteur ; Huihuang Su, Auteur ; Wenjun Gan, Auteur . - 2009 . - pp. 4340–4345.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4340–4345
Mots-clés : Epoxy prepregs Storage Fourier transform spectroscopies Dynamic mechanical analysis Rheological Time-resolved light scattering Optical microscopy Résumé : Changes in the properties of epoxy prepregs during storage are of both industrial and theoretical interest. It would be very helpful to have a test, suitable for production use, to determine when a prepreg has aged beyond acceptable limits. In this article, different epoxy prepregs aged under various conditions were studied by near-infrared (NIR) and mid-infrared (MIR) Fourier transform spectroscopies, dynamic mechanical analysis (DMA), rheological analysis, time-resolved light scattering (TRLS), and optical microscopy (OM). A very good relationship between storage aging time and curing conversion was obtained by NIR measurements. Furthermore, the rheological study showed that both the viscosity and the gelation time changed with storage aging. Changes in the glass transition temperatures of epoxy prepregs can result from either curing or phase separation during storage aging. The TRLS and OM results showed that structural evolution might occur during storage for some prepregs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018005 Exemplaires
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Titre : Enhancement of meltdown temperature of the polyethylene lithium-ion battery separator via surface coating with polymers having high thermal resistance Type de document : texte imprimé Auteurs : Y. S. Chung, Auteur ; S. H. Yoo, Auteur ; C. K. Kim, Auteur Année de publication : 2009 Article en page(s) : pp. 4346–4351 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Lithium-ion battery Polyethylene separators Thermal runaway reactions Résumé : When a lithium-ion battery is overcharged, it starts to self-heat because of exothermic reactions occurring within the components of the cell. Separator shutdown is a useful safety feature for preventing thermal runaway reactions in lithium-ion batteries. The polyethylene (PE) separators used here had shutdown temperatures of around 135 °C. Because the cell temperature continues to increase before actually beginning to cool even after shutdown, the separator should have a higher meltdown temperature than the shutdown temperature to work as an insulator even above the shutdown temperature. To enhance the meltdown temperature of the separator, in this study, a PE separator was coated with polymers synthesized from various ethylene glycol dimethacrylate monomers. When the separator was coated with polymer synthesized from diethylene glycol dimethacrylate (DEGDMA), its shutdown temperature and meltdown temperature were increased to 142 and 155 °C, respectively. Furthermore, a slight increase in the air permeability of the separator was observed when the separator was coated with polymer synthesized from an ethanol solution containing the proper amount of DEGDMA. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900096z
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4346–4351[article] Enhancement of meltdown temperature of the polyethylene lithium-ion battery separator via surface coating with polymers having high thermal resistance [texte imprimé] / Y. S. Chung, Auteur ; S. H. Yoo, Auteur ; C. K. Kim, Auteur . - 2009 . - pp. 4346–4351.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4346–4351
Mots-clés : Lithium-ion battery Polyethylene separators Thermal runaway reactions Résumé : When a lithium-ion battery is overcharged, it starts to self-heat because of exothermic reactions occurring within the components of the cell. Separator shutdown is a useful safety feature for preventing thermal runaway reactions in lithium-ion batteries. The polyethylene (PE) separators used here had shutdown temperatures of around 135 °C. Because the cell temperature continues to increase before actually beginning to cool even after shutdown, the separator should have a higher meltdown temperature than the shutdown temperature to work as an insulator even above the shutdown temperature. To enhance the meltdown temperature of the separator, in this study, a PE separator was coated with polymers synthesized from various ethylene glycol dimethacrylate monomers. When the separator was coated with polymer synthesized from diethylene glycol dimethacrylate (DEGDMA), its shutdown temperature and meltdown temperature were increased to 142 and 155 °C, respectively. Furthermore, a slight increase in the air permeability of the separator was observed when the separator was coated with polymer synthesized from an ethanol solution containing the proper amount of DEGDMA. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900096z Exemplaires
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Titre : Conceptual process design of integrated fermentation, deacylation, and crystallization in the production of β-lactam antibiotics Type de document : texte imprimé Auteurs : Carol A. Roa Engel, Auteur ; Straathof, Adrie J. J., Auteur ; Walter M. van Gulik, Auteur Année de publication : 2009 Article en page(s) : pp. 4352–4364 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : β -lactam nuclei production Fermentation Enzymatic deacylation Résumé : Integration of fermentation and downstream steps is required to improve the sustainability of industrial biotechnology processes. In this context, a new integrated process for β-lactam nuclei production is proposed, which has been theoretically investigated and conceptually designed. This process is an integration of fermentation and enzymatic deacylation of adipyl-7-aminodeacetoxycephalosporanic acid (adADCA) in one reactor producing 7-aminodeacetoxycephalosporanic acid (ADCA) directly from glucose. Although the deacylation equilibrium is unfavorable at the fermentation pH, it is pulled to completion because ADCA starts to crystallize and the liberated side chain, adipic acid (AA), is consumed by the fermentation. Therefore the integrated process requires much less AA than the nonintegrated process. In addition, the new process will lead to a reduction in number of downstream processing units, should avoid the use of acids and bases for pH shifts, and might lead to a reduction in waste salts production. A conceptual process was designed including an economic and technical analysis. The design goal was to produce 2000 tons/year of ADCA of 99% purity. Rigorous simulations were performed to evaluate different process options. Among the economic advantages of the new integrated process are 13.4% lower capital investments and 7.8% lower manufacturing costs. An analogous process for 6-aminopenicillanic acid (APA) is not feasible due to chemical degradation of this product. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801335r
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4352–4364[article] Conceptual process design of integrated fermentation, deacylation, and crystallization in the production of β-lactam antibiotics [texte imprimé] / Carol A. Roa Engel, Auteur ; Straathof, Adrie J. J., Auteur ; Walter M. van Gulik, Auteur . - 2009 . - pp. 4352–4364.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4352–4364
Mots-clés : β -lactam nuclei production Fermentation Enzymatic deacylation Résumé : Integration of fermentation and downstream steps is required to improve the sustainability of industrial biotechnology processes. In this context, a new integrated process for β-lactam nuclei production is proposed, which has been theoretically investigated and conceptually designed. This process is an integration of fermentation and enzymatic deacylation of adipyl-7-aminodeacetoxycephalosporanic acid (adADCA) in one reactor producing 7-aminodeacetoxycephalosporanic acid (ADCA) directly from glucose. Although the deacylation equilibrium is unfavorable at the fermentation pH, it is pulled to completion because ADCA starts to crystallize and the liberated side chain, adipic acid (AA), is consumed by the fermentation. Therefore the integrated process requires much less AA than the nonintegrated process. In addition, the new process will lead to a reduction in number of downstream processing units, should avoid the use of acids and bases for pH shifts, and might lead to a reduction in waste salts production. A conceptual process was designed including an economic and technical analysis. The design goal was to produce 2000 tons/year of ADCA of 99% purity. Rigorous simulations were performed to evaluate different process options. Among the economic advantages of the new integrated process are 13.4% lower capital investments and 7.8% lower manufacturing costs. An analogous process for 6-aminopenicillanic acid (APA) is not feasible due to chemical degradation of this product. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801335r Exemplaires
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Titre : Nanofibrous structure of nonwoven mats of electrospun biodegradable polymer nanocomposites : a design of experiments (DoE) study Type de document : texte imprimé Auteurs : A. Tsimpliaraki, Auteur ; S. Svinterikos, Auteur ; I. Zuburtikudis, Auteur Année de publication : 2009 Article en page(s) : pp. 4365–4374 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrospun biodegradable polymer nanocomposite Nanofibrous nonwoven mats Response-surface methodology Scanning electron microscopy Résumé : The morphology of nanofibrous nonwoven mats of an electrospun biodegradable polymer nanocomposite was studied in order to define the material and process parameter settings capable of giving the targeted nanofibrous structure of the mats. The polymer solution concentration, the flow rate of the injected solution, and the organically modified clay content of the polymer matrix were the investigated factors according to a design of experiments (DoE) within the context of response-surface methodology (RSM). Three responses were defined and were estimated by image processing of the scanning electron microscopy (SEM) micrographs. The first two were the ratio of the average bead-to-fiber diameter Dbead/Dfiber and the number surface density of the beads Nbead and were introduced to indicate the fibrous quality of the mats, while the third, indicative of the fiber thickness, was Dfiber. The developed quadratic models and the individual and coupling effect of the three factors examined are given. The results suggest that the dominant parameter affecting mats’ morphology is polymer solution concentration and that a broader range in the factor settings, especially for concentration, should be used in a subsequent optimization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801327z
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4365–4374[article] Nanofibrous structure of nonwoven mats of electrospun biodegradable polymer nanocomposites : a design of experiments (DoE) study [texte imprimé] / A. Tsimpliaraki, Auteur ; S. Svinterikos, Auteur ; I. Zuburtikudis, Auteur . - 2009 . - pp. 4365–4374.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4365–4374
Mots-clés : Electrospun biodegradable polymer nanocomposite Nanofibrous nonwoven mats Response-surface methodology Scanning electron microscopy Résumé : The morphology of nanofibrous nonwoven mats of an electrospun biodegradable polymer nanocomposite was studied in order to define the material and process parameter settings capable of giving the targeted nanofibrous structure of the mats. The polymer solution concentration, the flow rate of the injected solution, and the organically modified clay content of the polymer matrix were the investigated factors according to a design of experiments (DoE) within the context of response-surface methodology (RSM). Three responses were defined and were estimated by image processing of the scanning electron microscopy (SEM) micrographs. The first two were the ratio of the average bead-to-fiber diameter Dbead/Dfiber and the number surface density of the beads Nbead and were introduced to indicate the fibrous quality of the mats, while the third, indicative of the fiber thickness, was Dfiber. The developed quadratic models and the individual and coupling effect of the three factors examined are given. The results suggest that the dominant parameter affecting mats’ morphology is polymer solution concentration and that a broader range in the factor settings, especially for concentration, should be used in a subsequent optimization. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801327z Exemplaires
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Titre : Design of indirect heat recovery systems with variable-temperature storage for batch plants Type de document : texte imprimé Auteurs : Cheng-Liang Chen, Auteur ; Ying-Jyuan Ciou, Auteur Année de publication : 2009 Article en page(s) : pp. 4375–4387 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Heat recovery system Batch plant Variable-temperature storage transfer medium Résumé : This article aims to propose an iterative method for designing an indirect heat recovery system including the associated variable-temperature storage in a batch plant. A recirculated heat transfer medium (HTM) is applied to absorb surplus heat load from hot process streams and temporarily reserved in storage tanks, where the accumulated energy is then released to later cold process streams by exchanging heat with HTM. This work is a direct extension of one recent article where the restraint of constant temperature for HTM in each storage tank is relaxed to magnify the heat recovery potential. The design problem is formulated as a mixed-integer nonlinear program (MINLP) based on proposed superstructures. A novel iterative solution strategy for setting the variable temperatures of HTM in storage is provided by linking the network optimization tool (a GAMS program) and the streams temperature simulation software (a MATLAB program). One numerical example is explored to demonstrate the applicability of the proposed indirect heat exchanger network design method for batch processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013633
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4375–4387[article] Design of indirect heat recovery systems with variable-temperature storage for batch plants [texte imprimé] / Cheng-Liang Chen, Auteur ; Ying-Jyuan Ciou, Auteur . - 2009 . - pp. 4375–4387.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4375–4387
Mots-clés : Heat recovery system Batch plant Variable-temperature storage transfer medium Résumé : This article aims to propose an iterative method for designing an indirect heat recovery system including the associated variable-temperature storage in a batch plant. A recirculated heat transfer medium (HTM) is applied to absorb surplus heat load from hot process streams and temporarily reserved in storage tanks, where the accumulated energy is then released to later cold process streams by exchanging heat with HTM. This work is a direct extension of one recent article where the restraint of constant temperature for HTM in each storage tank is relaxed to magnify the heat recovery potential. The design problem is formulated as a mixed-integer nonlinear program (MINLP) based on proposed superstructures. A novel iterative solution strategy for setting the variable temperatures of HTM in storage is provided by linking the network optimization tool (a GAMS program) and the streams temperature simulation software (a MATLAB program). One numerical example is explored to demonstrate the applicability of the proposed indirect heat exchanger network design method for batch processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013633 Exemplaires
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Titre : Dynamic optimization of nonlinear processes with an enhanced scatter search method Type de document : texte imprimé Auteurs : Jose A. Egea, Auteur ; Balsa-Canto, Eva, Auteur ; María-Sonia G. García, Auteur Année de publication : 2009 Article en page(s) : pp. 4388–4401 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Scatter search method Nonlinear processes Control vector parametrization Résumé : An enhanced scatter search method for the global dynamic optimization of nonlinear processes using the control vector parametrization (CVP) approach is presented. Sharing some features of the scatter search metaheuristic, this new method presents a simpler but more effective design which helps to overcome typical difficulties of nonlinear dynamic systems optimization such as noise, flat areas, nonsmoothness, and/or discontinuities. This new algorithm provides a good balance between robustness and efficiency in the global phase, and couples a local search procedure to accelerate the convergence to optimal solutions. Its application to four multimodal dynamic optimization problems, compared with other state-of-the-art global optimization algorithms, including an advanced scatter search design, proves its efficiency and robustness, showing a very good scalability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801717t
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4388–4401[article] Dynamic optimization of nonlinear processes with an enhanced scatter search method [texte imprimé] / Jose A. Egea, Auteur ; Balsa-Canto, Eva, Auteur ; María-Sonia G. García, Auteur . - 2009 . - pp. 4388–4401.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4388–4401
Mots-clés : Scatter search method Nonlinear processes Control vector parametrization Résumé : An enhanced scatter search method for the global dynamic optimization of nonlinear processes using the control vector parametrization (CVP) approach is presented. Sharing some features of the scatter search metaheuristic, this new method presents a simpler but more effective design which helps to overcome typical difficulties of nonlinear dynamic systems optimization such as noise, flat areas, nonsmoothness, and/or discontinuities. This new algorithm provides a good balance between robustness and efficiency in the global phase, and couples a local search procedure to accelerate the convergence to optimal solutions. Its application to four multimodal dynamic optimization problems, compared with other state-of-the-art global optimization algorithms, including an advanced scatter search design, proves its efficiency and robustness, showing a very good scalability. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801717t Exemplaires
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Titre : Effectiveness of intravenous infusion algorithms for glucose control in diabetic patients using different simulation models Type de document : texte imprimé Auteurs : Terry G. Farmer Jr., Auteur ; Thomas F. Edgar, Auteur ; Nicholas A. Peppas, Auteur Année de publication : 2009 Article en page(s) : pp. 4402–4414 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Insulin infusion algorithms Glucose dynamics Diabetes patient Proportional integral derivative control Résumé : The effectiveness of closed-loop insulin infusion algorithms is assessed for three different mathematical models describing insulin and glucose dynamics within a type I diabetes patient. Simulations are performed to assess the effectiveness of proportional plus integral plus derivative (PID) control, feedforward control, and a physiologically based control system with respect to maintaining normal glucose levels during a meal and during exercise. Control effectiveness is assessed by comparing the simulated response to a simulation of a healthy patient during both a meal and exercise and establishing maximum and minimum glucose levels and insulin infusion levels, as well as maximum duration of hyperglycemia. Controller effectiveness is assessed within the minimal model, the Sorensen model, and the Hovorka model. Results showed that no type of control was able to maintain normal conditions when simulations were performed using the minimal model. For both the Sorensen model and the Hovorka model, proportional control was sufficient to maintain normal glucose levels. Given published clinical data showing the ineffectiveness of PID control in patients, the work demonstrates that controller success based on simulation results can be misleading, and that future work should focus on addressing the model discrepancies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800871t
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4402–4414[article] Effectiveness of intravenous infusion algorithms for glucose control in diabetic patients using different simulation models [texte imprimé] / Terry G. Farmer Jr., Auteur ; Thomas F. Edgar, Auteur ; Nicholas A. Peppas, Auteur . - 2009 . - pp. 4402–4414.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4402–4414
Mots-clés : Insulin infusion algorithms Glucose dynamics Diabetes patient Proportional integral derivative control Résumé : The effectiveness of closed-loop insulin infusion algorithms is assessed for three different mathematical models describing insulin and glucose dynamics within a type I diabetes patient. Simulations are performed to assess the effectiveness of proportional plus integral plus derivative (PID) control, feedforward control, and a physiologically based control system with respect to maintaining normal glucose levels during a meal and during exercise. Control effectiveness is assessed by comparing the simulated response to a simulation of a healthy patient during both a meal and exercise and establishing maximum and minimum glucose levels and insulin infusion levels, as well as maximum duration of hyperglycemia. Controller effectiveness is assessed within the minimal model, the Sorensen model, and the Hovorka model. Results showed that no type of control was able to maintain normal conditions when simulations were performed using the minimal model. For both the Sorensen model and the Hovorka model, proportional control was sufficient to maintain normal glucose levels. Given published clinical data showing the ineffectiveness of PID control in patients, the work demonstrates that controller success based on simulation results can be misleading, and that future work should focus on addressing the model discrepancies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800871t Exemplaires
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Titre : Online model-based redesign of experiments for parameter estimation in dynamic systems Type de document : texte imprimé Auteurs : Federico Galvanin, Auteur ; Massimiliano Barolo, Auteur ; Fabrizio Bezzo, Auteur Année de publication : 2009 Article en page(s) : pp. 4415–4427 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dynamic systems Online model-based Résumé : The optimal model-based design of experiments aims at designing a set of dynamic experiments yielding the most informative process data to be used for the estimation of the parameters of a first-principles dynamic process model. According to the usual procedure for parameter estimation, the experiment is first designed offline; then, the experiment is carried out in the plant, and process measurements are collected; and finally, parameters are estimated after completion of the experiment. Therefore, the information gathered during the evolution of the experiment is analyzed only at the end of the experiment itself. Since the experiment is designed on the basis of the parameter estimates available before the experiment is started, the progressive increase of the information resulting from the progress of the experiment is not exploited by the designer until the end of that experiment. In this paper, a strategy for the online model-based redesign of experiments is proposed to exploit the information as soon as it is generated from the execution of an experiment, and its performance is compared to that of a standard optimal experiment design approach. Intermediate parameter estimations are carried out while the experiment is running, and by exploiting the information obtained, the experiment is partially redesigned before its termination, with the purpose of updating the experimental settings to generate more valuable information for subsequent analysis. This enables us to reduce the number of experimental trials that are needed to reach a statistically sound estimation of the model parameters and results in a reduction of experimental time, raw materials needs, number of samples to be analyzed, control effort, and labor. Two simulated case studies of increasing level of complexity are used to demonstrate the benefits of the proposed approach with respect to a state-of-the-art sequential model-based experiment design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018356
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4415–4427[article] Online model-based redesign of experiments for parameter estimation in dynamic systems [texte imprimé] / Federico Galvanin, Auteur ; Massimiliano Barolo, Auteur ; Fabrizio Bezzo, Auteur . - 2009 . - pp. 4415–4427.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4415–4427
Mots-clés : Dynamic systems Online model-based Résumé : The optimal model-based design of experiments aims at designing a set of dynamic experiments yielding the most informative process data to be used for the estimation of the parameters of a first-principles dynamic process model. According to the usual procedure for parameter estimation, the experiment is first designed offline; then, the experiment is carried out in the plant, and process measurements are collected; and finally, parameters are estimated after completion of the experiment. Therefore, the information gathered during the evolution of the experiment is analyzed only at the end of the experiment itself. Since the experiment is designed on the basis of the parameter estimates available before the experiment is started, the progressive increase of the information resulting from the progress of the experiment is not exploited by the designer until the end of that experiment. In this paper, a strategy for the online model-based redesign of experiments is proposed to exploit the information as soon as it is generated from the execution of an experiment, and its performance is compared to that of a standard optimal experiment design approach. Intermediate parameter estimations are carried out while the experiment is running, and by exploiting the information obtained, the experiment is partially redesigned before its termination, with the purpose of updating the experimental settings to generate more valuable information for subsequent analysis. This enables us to reduce the number of experimental trials that are needed to reach a statistically sound estimation of the model parameters and results in a reduction of experimental time, raw materials needs, number of samples to be analyzed, control effort, and labor. Two simulated case studies of increasing level of complexity are used to demonstrate the benefits of the proposed approach with respect to a state-of-the-art sequential model-based experiment design. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018356 Exemplaires
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Titre : Modeling and simulation of stirred dead end ultrafiltration process using the aspen engineering suite Type de document : texte imprimé Auteurs : Sabuj Das, Auteur ; Prabirkumar Saha, Auteur ; G. Pugazhenthi, Auteur Année de publication : 2009 Article en page(s) : pp. 4428–4439 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pressure-driven membrane process Stirred cell Aspen engineering suite Résumé : Simulation of pressure-driven membrane process has been carried out considering two different types of solute (silica and dextran) and membrane (partially permeable and totally retentive) in a stirred cell using the Aspen Engineering Suite. One solute, silica, exerts negligible osmotic pressure but the other, dextran, offers adequate osmotic pressure. Silica is very susceptible to form a gel layer while dextran has no such tendency. Two types of membrane are considered for this work. One membrane completely separates solute from the solvent (totally retentive membrane) and the other does it partially (partially permeable membrane). The second type of membrane is regarded as highly compact granulated particle layer which has a different range of porosity. So the diffusivity within the membrane layer is referred to as hindered back diffusion. Osmotic pressure model and gel polarization model have been considered for batch and continuous mode operation. Silica suspension has been simulated with totally retentive membrane and dextran solution is simulated with partially retentive membrane in batch and continuous mode, respectively. The effect of applied pressure, stirring speed, and initial feed concentration on permeate flux, membrane surface concentration, permeate concentration, and true and observed rejection have been studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801293d
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4428–4439[article] Modeling and simulation of stirred dead end ultrafiltration process using the aspen engineering suite [texte imprimé] / Sabuj Das, Auteur ; Prabirkumar Saha, Auteur ; G. Pugazhenthi, Auteur . - 2009 . - pp. 4428–4439.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4428–4439
Mots-clés : Pressure-driven membrane process Stirred cell Aspen engineering suite Résumé : Simulation of pressure-driven membrane process has been carried out considering two different types of solute (silica and dextran) and membrane (partially permeable and totally retentive) in a stirred cell using the Aspen Engineering Suite. One solute, silica, exerts negligible osmotic pressure but the other, dextran, offers adequate osmotic pressure. Silica is very susceptible to form a gel layer while dextran has no such tendency. Two types of membrane are considered for this work. One membrane completely separates solute from the solvent (totally retentive membrane) and the other does it partially (partially permeable membrane). The second type of membrane is regarded as highly compact granulated particle layer which has a different range of porosity. So the diffusivity within the membrane layer is referred to as hindered back diffusion. Osmotic pressure model and gel polarization model have been considered for batch and continuous mode operation. Silica suspension has been simulated with totally retentive membrane and dextran solution is simulated with partially retentive membrane in batch and continuous mode, respectively. The effect of applied pressure, stirring speed, and initial feed concentration on permeate flux, membrane surface concentration, permeate concentration, and true and observed rejection have been studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801293d Exemplaires
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Titre : Polyphenol polymerization by horseradish peroxidase for metal adsorption studies Type de document : texte imprimé Auteurs : Hidetaka Kawakita, Auteur ; Kohshi Hamamoto, Auteur ; Keisuke Ohto, Auteur Année de publication : 2009 Article en page(s) : pp. 4440–4444 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyphenol Horseradish peroxidase reaction Fourier transform infrared spectrometry Size-exclusion chromatography Metal adsorption Résumé : Four phenol derivatives (m-cresol, 3-methylcatechol, 4-methylcatechol, and 4-ethylcatechol) were polymerized using the horseradish peroxidase reaction, and their metal adsorption capabilities were studied. Fourier transform infrared (FT-IR) spectrometry and size-exclusion chromatography indicated that the phenol monomers polymerized to give polyphenols having molecular weights from 700 to 3000. During metal adsorption studies, poly(3-methylcatechol) adsorbed copper ions at 100% in a solution of pH 5.0, whereas poly(m-cresol) failed to adsorb any copper ions. Gold ions selectively adsorbed to poly(4-ethylcatechol) in acid media and formed gold particles via reduction of the polyphenol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800830m
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4440–4444[article] Polyphenol polymerization by horseradish peroxidase for metal adsorption studies [texte imprimé] / Hidetaka Kawakita, Auteur ; Kohshi Hamamoto, Auteur ; Keisuke Ohto, Auteur . - 2009 . - pp. 4440–4444.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4440–4444
Mots-clés : Polyphenol Horseradish peroxidase reaction Fourier transform infrared spectrometry Size-exclusion chromatography Metal adsorption Résumé : Four phenol derivatives (m-cresol, 3-methylcatechol, 4-methylcatechol, and 4-ethylcatechol) were polymerized using the horseradish peroxidase reaction, and their metal adsorption capabilities were studied. Fourier transform infrared (FT-IR) spectrometry and size-exclusion chromatography indicated that the phenol monomers polymerized to give polyphenols having molecular weights from 700 to 3000. During metal adsorption studies, poly(3-methylcatechol) adsorbed copper ions at 100% in a solution of pH 5.0, whereas poly(m-cresol) failed to adsorb any copper ions. Gold ions selectively adsorbed to poly(4-ethylcatechol) in acid media and formed gold particles via reduction of the polyphenol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800830m Exemplaires
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Titre : Separation of concentrated binary gases by hybrid pressure-swing adsorption/simulated-moving bed processes Type de document : texte imprimé Auteurs : Kyle P. Kostroski, Auteur ; Phillip C. Wankat, Auteur Année de publication : 2009 Article en page(s) : pp. 4445–4465 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Stripping-type PSA Rectifying-type Gas separation Simulated-moving bed Résumé : Stripping-type PSA (S-PSA) is a commonly used gas separation process for purification of the light component. Rectifying-type PSA (R-PSA), although not commonly used, is a gas separation process for purifying predominately the heavy component. Because S-PSA and R-PSA each tend to favor the production of a single product, these processes are typically not used for complete binary separation. On the other hand, the gas-phase simulated-moving bed (SMB) is capable of achieving complete binary separation; however, its commercial application has been stymied by the need for carrier gas/desorbent recovery and unfavorable economics. In this work, S-PSA and R-PSA are combined with a two-zone SMB to develop S-PSA/SMB and R-PSA/SMB hybrid processes and these processes are integrated into combination-type C-PSA/SMB processes. Combining PSA and SMB eliminates the carrier gas/desorbent by taking advantage of gas expansion and by using both light and heavy purge streams. Separation of H2 and CH4 mixtures with Zeolite 5A was simulated to determine the feasibility of the hybrid processes. The primary products are H2 and CH4 plus an impure offgas may be produced. Complete binary separation can be achieved by recycling the entire offgas stream. The best separation was achieved with an eight-bed combination of the S-PSA/SMB and R-PSA/SMB processes, the SRC-PSA/SMB. This process separated a 70% H2/30% CH4 feed into 99.99% H2 with 99.6% H2 recovery and 99% CH4 with 99.9% CH4 recovery with productivity of 9.37 × 10−5 mol feed/(kg·s) and an energy requirement of 260.9 kJ/mol feed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801371t
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4445–4465[article] Separation of concentrated binary gases by hybrid pressure-swing adsorption/simulated-moving bed processes [texte imprimé] / Kyle P. Kostroski, Auteur ; Phillip C. Wankat, Auteur . - 2009 . - pp. 4445–4465.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4445–4465
Mots-clés : Stripping-type PSA Rectifying-type Gas separation Simulated-moving bed Résumé : Stripping-type PSA (S-PSA) is a commonly used gas separation process for purification of the light component. Rectifying-type PSA (R-PSA), although not commonly used, is a gas separation process for purifying predominately the heavy component. Because S-PSA and R-PSA each tend to favor the production of a single product, these processes are typically not used for complete binary separation. On the other hand, the gas-phase simulated-moving bed (SMB) is capable of achieving complete binary separation; however, its commercial application has been stymied by the need for carrier gas/desorbent recovery and unfavorable economics. In this work, S-PSA and R-PSA are combined with a two-zone SMB to develop S-PSA/SMB and R-PSA/SMB hybrid processes and these processes are integrated into combination-type C-PSA/SMB processes. Combining PSA and SMB eliminates the carrier gas/desorbent by taking advantage of gas expansion and by using both light and heavy purge streams. Separation of H2 and CH4 mixtures with Zeolite 5A was simulated to determine the feasibility of the hybrid processes. The primary products are H2 and CH4 plus an impure offgas may be produced. Complete binary separation can be achieved by recycling the entire offgas stream. The best separation was achieved with an eight-bed combination of the S-PSA/SMB and R-PSA/SMB processes, the SRC-PSA/SMB. This process separated a 70% H2/30% CH4 feed into 99.99% H2 with 99.6% H2 recovery and 99% CH4 with 99.9% CH4 recovery with productivity of 9.37 × 10−5 mol feed/(kg·s) and an energy requirement of 260.9 kJ/mol feed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801371t Exemplaires
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Titre : Experimental study on adsorption of carbon dioxide by 5A molecular sieve for helium purification of high-temperature gas-cooled reactor Type de document : texte imprimé Auteurs : Hua Chang, Auteur ; Zong-Xin Wu, Auteur Année de publication : 2009 Article en page(s) : pp. 4466–4473 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Fixed-bed apparatus Proportional gas mixing system Carbon dioxide--adsorption Helium purification High-temperature gas-cooled reactors Résumé : A fixed-bed apparatus with the dynamic two-route proportional gas mixing system was designed to investigate the adsorption behavior of carbon dioxide on 5A molecular sieve for designing the helium purification system of high-temperature gas-cooled reactors (HTGR). Experiments were performed at near atmospheric pressure, and the dynamic column breakthrough method was used to derive the single-component adsorption equilibrium of carbon dioxide with helium as the carrier gas. The breakthrough curves and the desorption curves were measured at low carbon dioxide partial pressure of 10−150 Pa and temperatures of 5−35 °C. By analyzing the breakthrough curve, both the equilibrium adsorption capacity and the kinetic adsorption capacity at the breakthrough point were determined. The effects of superficial velocity, temperature, gas feed concentration, adsorption pressure, and regeneration temperature on the adsorption capability were studied. The CO2 single-component adsorption isotherm at 10 °C was obtained and fitted well by the Langmuir and the Freundlich isotherm models. The heat of adsorption for carbon dioxide on 5A molecular sieve was estimated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8008814
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4466–4473[article] Experimental study on adsorption of carbon dioxide by 5A molecular sieve for helium purification of high-temperature gas-cooled reactor [texte imprimé] / Hua Chang, Auteur ; Zong-Xin Wu, Auteur . - 2009 . - pp. 4466–4473.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4466–4473
Mots-clés : Fixed-bed apparatus Proportional gas mixing system Carbon dioxide--adsorption Helium purification High-temperature gas-cooled reactors Résumé : A fixed-bed apparatus with the dynamic two-route proportional gas mixing system was designed to investigate the adsorption behavior of carbon dioxide on 5A molecular sieve for designing the helium purification system of high-temperature gas-cooled reactors (HTGR). Experiments were performed at near atmospheric pressure, and the dynamic column breakthrough method was used to derive the single-component adsorption equilibrium of carbon dioxide with helium as the carrier gas. The breakthrough curves and the desorption curves were measured at low carbon dioxide partial pressure of 10−150 Pa and temperatures of 5−35 °C. By analyzing the breakthrough curve, both the equilibrium adsorption capacity and the kinetic adsorption capacity at the breakthrough point were determined. The effects of superficial velocity, temperature, gas feed concentration, adsorption pressure, and regeneration temperature on the adsorption capability were studied. The CO2 single-component adsorption isotherm at 10 °C was obtained and fitted well by the Langmuir and the Freundlich isotherm models. The heat of adsorption for carbon dioxide on 5A molecular sieve was estimated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8008814 Exemplaires
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Titre : Mixed matrix PVDF hollow fiber membranes with nanoscale pores for desalination through direct contact membrane distillation Type de document : texte imprimé Auteurs : Kai Yu Wang, Auteur ; Suay Wei Foo, Auteur ; Tai-Shung Chung, Auteur Année de publication : 2009 Article en page(s) : pp. 4474–4483 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Direct contact membrane distillation Poly(vinylidene fluoride Hollow fiber membranes Dry-jet wet Résumé : Highly porous hydrophobic hollow fiber membranes with high porosity and sandwich trilayer structure were specially designed to meet the requirements of direct contact membrane distillation (DCMD). Poly(vinylidene fluoride) (PVDF)/Cloisite clay composite hollow fibers were fabricated based on the dry-jet wet phase inversion mechanism by using water as both the external and internal coagulants. Membrane void fraction of up to 90% can be produced to improve the fibers’ thermal insulation and reduce vapor transport resistance. The fiber inner surface was full of streaky pores with pore size less than 1.0 μm in diameter, while the pores on the fiber outer surface were much smaller, less than 50 nm in diameter. This demonstrates that membrane pores fabricated at a nanoscale can achieve high water vapor permeation flux with 100% salt rejection. For example, the fabricated PVDF/clay composite hollow fiber was tested by desalinating a 3.5 wt % NaCl solution and permeation flux as high as 79.2 kg/(m2·h) (calculated on the fiber outer diameter) was achieved at the inlet temperatures of 81.5/17.5 °C. The performance shows almost no decay during 220-h continuous tests. The addition of clay particles may enhance the tensile modulus and improve long-term stability compared to those fibers without particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009704
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4474–4483[article] Mixed matrix PVDF hollow fiber membranes with nanoscale pores for desalination through direct contact membrane distillation [texte imprimé] / Kai Yu Wang, Auteur ; Suay Wei Foo, Auteur ; Tai-Shung Chung, Auteur . - 2009 . - pp. 4474–4483.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4474–4483
Mots-clés : Direct contact membrane distillation Poly(vinylidene fluoride Hollow fiber membranes Dry-jet wet Résumé : Highly porous hydrophobic hollow fiber membranes with high porosity and sandwich trilayer structure were specially designed to meet the requirements of direct contact membrane distillation (DCMD). Poly(vinylidene fluoride) (PVDF)/Cloisite clay composite hollow fibers were fabricated based on the dry-jet wet phase inversion mechanism by using water as both the external and internal coagulants. Membrane void fraction of up to 90% can be produced to improve the fibers’ thermal insulation and reduce vapor transport resistance. The fiber inner surface was full of streaky pores with pore size less than 1.0 μm in diameter, while the pores on the fiber outer surface were much smaller, less than 50 nm in diameter. This demonstrates that membrane pores fabricated at a nanoscale can achieve high water vapor permeation flux with 100% salt rejection. For example, the fabricated PVDF/clay composite hollow fiber was tested by desalinating a 3.5 wt % NaCl solution and permeation flux as high as 79.2 kg/(m2·h) (calculated on the fiber outer diameter) was achieved at the inlet temperatures of 81.5/17.5 °C. The performance shows almost no decay during 220-h continuous tests. The addition of clay particles may enhance the tensile modulus and improve long-term stability compared to those fibers without particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009704 Exemplaires
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Titre : Reduction of energy consumption in the process industry using a heat-integrated hybrid distillation pervaporation process Type de document : texte imprimé Auteurs : Maria T. Del Pozo Gomez, Auteur ; Jens-Uwe Repke, Auteur ; Deu-yeun Kim, Auteur Année de publication : 2009 Article en page(s) : pp. 4484–4494 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hybrid distillation pervaporation process Heat integration Condensation energy Résumé : In the present work, the advantages of using heat integration in a hybrid distillation pervaporation process are studied and, on the basis of the developed model, the industrial applicability of the process is analyzed. The basic idea of the heat integration is to condense the distillate stream in a heat-exchanger pipe inside the membrane. The condensation energy is directly released into the process, not needing external heat exchangers to preheat the membrane feed. This is reflected in an important reduction in the process energy consumption. Experimental work has been carried out in order to characterize the membrane and to prove the positive influence of the heat integration. A rigorous model for the pervaporation process has been developed and validated. Additionally, simulation studies take place in order to compare the energy supply in the proposed process with a typical industrial process layout. As a result, in comparison to the results of Sommer and Melin [Sommer, S; Melin, T. Ind. Eng. Chem. Res. 2004, 43, 5248−5259], energy savings of 44.7% can be achieved. Further study has been realized in order to prove the reduction in the specific separation costs. The operation conditions have been varied, finding always lower specific separation costs in the heat integrated case. In the optimal operation point, the reduction reaches its maximum value of 20%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801540a
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4484–4494[article] Reduction of energy consumption in the process industry using a heat-integrated hybrid distillation pervaporation process [texte imprimé] / Maria T. Del Pozo Gomez, Auteur ; Jens-Uwe Repke, Auteur ; Deu-yeun Kim, Auteur . - 2009 . - pp. 4484–4494.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4484–4494
Mots-clés : Hybrid distillation pervaporation process Heat integration Condensation energy Résumé : In the present work, the advantages of using heat integration in a hybrid distillation pervaporation process are studied and, on the basis of the developed model, the industrial applicability of the process is analyzed. The basic idea of the heat integration is to condense the distillate stream in a heat-exchanger pipe inside the membrane. The condensation energy is directly released into the process, not needing external heat exchangers to preheat the membrane feed. This is reflected in an important reduction in the process energy consumption. Experimental work has been carried out in order to characterize the membrane and to prove the positive influence of the heat integration. A rigorous model for the pervaporation process has been developed and validated. Additionally, simulation studies take place in order to compare the energy supply in the proposed process with a typical industrial process layout. As a result, in comparison to the results of Sommer and Melin [Sommer, S; Melin, T. Ind. Eng. Chem. Res. 2004, 43, 5248−5259], energy savings of 44.7% can be achieved. Further study has been realized in order to prove the reduction in the specific separation costs. The operation conditions have been varied, finding always lower specific separation costs in the heat integrated case. In the optimal operation point, the reduction reaches its maximum value of 20%. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801540a Exemplaires
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Titre : Impregnating zirconium phosphate onto porous polymers for lead removal from waters : effect of nanosized particles and polymer chemistry Type de document : texte imprimé Auteurs : Qingrui Zhang, Auteur ; Peijuan Jiang, Auteur ; Bingcai Pan, Auteur Année de publication : 2009 Article en page(s) : pp. 4495–4499 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polymer-based zirconium phosphate Chloromethylated polystyrene Polystyrene cation exchange resin X-ray diffraction Résumé : The subject study revealed several unique properties of polymer-based zirconium phosphate (ZrP) for lead removal from waters. ZrP particles were impregnated within two porous polymers, namely, a chloromethylated polystyrene (CP) and a polystyrene cation exchange resin (D-001). Both as-prepared hybrid sorbents (designated ZrP−CP and ZrP−001, respectively) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and a N2 adsorption−desorption test at 77 K. As compared to the fresh particles, ZrP impregnated onto CP exhibits a slight increase in sorption capacity, which may result from their nanosized particles after impregnation. More attractively, ZrP−001 displays much higher sorption preference toward lead ions over calcium ions than ZrP, D-001, and ZrP−CP. Such significant phenomena is mainly attributed to the Donnan membrane effect exerted by the immobilized sulfonate groups on D-001 and further validates its potential application for enhanced removal of the toxic metal from contaminated waters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016847
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4495–4499[article] Impregnating zirconium phosphate onto porous polymers for lead removal from waters : effect of nanosized particles and polymer chemistry [texte imprimé] / Qingrui Zhang, Auteur ; Peijuan Jiang, Auteur ; Bingcai Pan, Auteur . - 2009 . - pp. 4495–4499.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4495–4499
Mots-clés : Polymer-based zirconium phosphate Chloromethylated polystyrene Polystyrene cation exchange resin X-ray diffraction Résumé : The subject study revealed several unique properties of polymer-based zirconium phosphate (ZrP) for lead removal from waters. ZrP particles were impregnated within two porous polymers, namely, a chloromethylated polystyrene (CP) and a polystyrene cation exchange resin (D-001). Both as-prepared hybrid sorbents (designated ZrP−CP and ZrP−001, respectively) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and a N2 adsorption−desorption test at 77 K. As compared to the fresh particles, ZrP impregnated onto CP exhibits a slight increase in sorption capacity, which may result from their nanosized particles after impregnation. More attractively, ZrP−001 displays much higher sorption preference toward lead ions over calcium ions than ZrP, D-001, and ZrP−CP. Such significant phenomena is mainly attributed to the Donnan membrane effect exerted by the immobilized sulfonate groups on D-001 and further validates its potential application for enhanced removal of the toxic metal from contaminated waters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016847 Exemplaires
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Titre : The separation and concentration of Cr(VI) from acidic dilute solution using hollow fiber renewal liquid membrane Type de document : texte imprimé Auteurs : Junteng Liu, Auteur ; Zhang, Weidong, Auteur ; Zhongqi Ren, Auteur Année de publication : 2009 Article en page(s) : pp. 4500–4506 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow fiber HFRLM technique Cr(VI) Acidic dilute solution Tri-n-butyl phosphate Résumé : Hollow fiber renewal liquid membrane (HFRLM) technique for simultaneous separation and concentration of Cr(VI) from acidic dilute solution has been studied using tri-n-butyl phosphate as mobile carrier. The influences of the mobile carrier concentration, pH of the feed phase, the initial Cr(VI) concentration, and the stripping concentration on the mass transfer rate are investigated. The transport rate of Cr(VI) increases with increasing the carrier concentration and the stripping concentration, then reaches a “plateau”. The concentration factor as high as 25∼30 has been achieved easily. A mathematical model is proposed to explain the transport mechanism. The validity of this model is evaluated and good agreement between predicted results and experiment data are obtained. Results suggest that the HFRLM technique provides a promising alternative to treat industrial wastewater at low Cr(VI) concentration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017669
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4500–4506[article] The separation and concentration of Cr(VI) from acidic dilute solution using hollow fiber renewal liquid membrane [texte imprimé] / Junteng Liu, Auteur ; Zhang, Weidong, Auteur ; Zhongqi Ren, Auteur . - 2009 . - pp. 4500–4506.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4500–4506
Mots-clés : Hollow fiber HFRLM technique Cr(VI) Acidic dilute solution Tri-n-butyl phosphate Résumé : Hollow fiber renewal liquid membrane (HFRLM) technique for simultaneous separation and concentration of Cr(VI) from acidic dilute solution has been studied using tri-n-butyl phosphate as mobile carrier. The influences of the mobile carrier concentration, pH of the feed phase, the initial Cr(VI) concentration, and the stripping concentration on the mass transfer rate are investigated. The transport rate of Cr(VI) increases with increasing the carrier concentration and the stripping concentration, then reaches a “plateau”. The concentration factor as high as 25∼30 has been achieved easily. A mathematical model is proposed to explain the transport mechanism. The validity of this model is evaluated and good agreement between predicted results and experiment data are obtained. Results suggest that the HFRLM technique provides a promising alternative to treat industrial wastewater at low Cr(VI) concentration. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017669 Exemplaires
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Titre : Preparation of uniform microcapsules containing 1-octanol for caprolactam extraction Type de document : texte imprimé Auteurs : Xingchu Gong, Auteur ; Yangcheng Lu, Auteur ; Zhixi Qian, Auteur Année de publication : 2009 Article en page(s) : pp. 4507–4513 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polysulfone microcapsules 1-octanol Coaxial microchannel N2 gas Caprolactam extraction Résumé : This paper presents a novel method to prepare uniform polysulfone (PSF) microcapsules that contain 1-octanol to prevent emulsification when pure 1-octanol is used as the solvent. In this method, a coaxial microchannel device was designed and N2 gas was introduced to control the drop size of polymer solution. Uniform microcapsules were successfully prepared and the diameter decreased linearly with the increase of the N2 flow rate. The pore volume and 1-octanol loading ratio could be controlled by changing the PSF content in polymer solution. The maximum loading of 1-octanol was 6.98 g/g PSF when the pore volume was 8.28 mL/g. The extraction capacity of the prepared microcapsules was determined, and it was found that the uptake of caprolactam was mainly influenced by the 1-octanol mass fraction in microcapsules, because the PSF shell did not adsorb much caprolactam. A maximum uptake of 58.8 mg caprolactam/g microcapsule was reached. The extraction kinetics of the prepared microcapsules also was determined. It was determined that the mass-transfer rate was determined by inner diffusion. The apparent diffusion coefficient of 9.1 × 10−11 m2/s was obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900046u
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4507–4513[article] Preparation of uniform microcapsules containing 1-octanol for caprolactam extraction [texte imprimé] / Xingchu Gong, Auteur ; Yangcheng Lu, Auteur ; Zhixi Qian, Auteur . - 2009 . - pp. 4507–4513.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4507–4513
Mots-clés : Polysulfone microcapsules 1-octanol Coaxial microchannel N2 gas Caprolactam extraction Résumé : This paper presents a novel method to prepare uniform polysulfone (PSF) microcapsules that contain 1-octanol to prevent emulsification when pure 1-octanol is used as the solvent. In this method, a coaxial microchannel device was designed and N2 gas was introduced to control the drop size of polymer solution. Uniform microcapsules were successfully prepared and the diameter decreased linearly with the increase of the N2 flow rate. The pore volume and 1-octanol loading ratio could be controlled by changing the PSF content in polymer solution. The maximum loading of 1-octanol was 6.98 g/g PSF when the pore volume was 8.28 mL/g. The extraction capacity of the prepared microcapsules was determined, and it was found that the uptake of caprolactam was mainly influenced by the 1-octanol mass fraction in microcapsules, because the PSF shell did not adsorb much caprolactam. A maximum uptake of 58.8 mg caprolactam/g microcapsule was reached. The extraction kinetics of the prepared microcapsules also was determined. It was determined that the mass-transfer rate was determined by inner diffusion. The apparent diffusion coefficient of 9.1 × 10−11 m2/s was obtained. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900046u Exemplaires
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Titre : CFD modeling of immobilized phenol biodegradation in three-phase airlift loop reactor Type de document : texte imprimé Auteurs : Xiaoqiang Jia, Auteur ; Jianping Wen, Auteur ; Xue Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 4514–4529 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CFD model Phenol biodegradation Airlift loop reactor Résumé : A 3D transient CFD model was developed to simulate the dynamic behaviors of batch phenol biodegradation by immobilized Candida tropicalis in a gas−liquid−solid three-phase airlift loop reactor (ALR), coupling of three-phase fluid flow, species interphase mass transfer, and intrinsic bioreaction, with the bubble size distribution (BSD) determined by the multiple size group (MUSIG) model. Simulation of the time courses of the volume-averaged species mass concentrations in the riser and downcomer of the ALR was performed, whereas the phenol and oxygen concentrations in the liquid phase were validated by corresponding experiments. Source-term comparisons between species interphase mass transfer and bioreaction were done to distinguish the rate-limiting step in the process. Moreover, local transient phenol biodegradation characteristics such as oxygen concentration profiles in the gas, liquid, and solid phases; phenol concentration profiles in the liquid and solid phases; and cell concentration profiles in the solid phase were all predicted reasonably well. Furthermore, the performances of the ALR and a bubble column reactor (BCR) were compared, and the advantage of the former reactor was confirmed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800816d
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4514–4529[article] CFD modeling of immobilized phenol biodegradation in three-phase airlift loop reactor [texte imprimé] / Xiaoqiang Jia, Auteur ; Jianping Wen, Auteur ; Xue Wang, Auteur . - 2009 . - pp. 4514–4529.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4514–4529
Mots-clés : CFD model Phenol biodegradation Airlift loop reactor Résumé : A 3D transient CFD model was developed to simulate the dynamic behaviors of batch phenol biodegradation by immobilized Candida tropicalis in a gas−liquid−solid three-phase airlift loop reactor (ALR), coupling of three-phase fluid flow, species interphase mass transfer, and intrinsic bioreaction, with the bubble size distribution (BSD) determined by the multiple size group (MUSIG) model. Simulation of the time courses of the volume-averaged species mass concentrations in the riser and downcomer of the ALR was performed, whereas the phenol and oxygen concentrations in the liquid phase were validated by corresponding experiments. Source-term comparisons between species interphase mass transfer and bioreaction were done to distinguish the rate-limiting step in the process. Moreover, local transient phenol biodegradation characteristics such as oxygen concentration profiles in the gas, liquid, and solid phases; phenol concentration profiles in the liquid and solid phases; and cell concentration profiles in the solid phase were all predicted reasonably well. Furthermore, the performances of the ALR and a bubble column reactor (BCR) were compared, and the advantage of the former reactor was confirmed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800816d Exemplaires
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Titre : The roles of the surface charge and hydroxyl group on a Fe−Al−Ce adsorbent in fluoride adsorption Type de document : texte imprimé Auteurs : Hai-Xia Wu, Auteur ; Ting-Jie Wang, Auteur ; Lin Chen, Auteur Année de publication : 2009 Article en page(s) : pp. 4530–4534 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Surface charge Hydroxyl group Fe− Al− Ce adsorbent Fluoride adsorption External voltage Résumé : The roles of the surface charge and hydroxyl group on a Fe−Al−Ce adsorbent in fluoride adsorption were studied. Fluoride adsorption at different initial solution pH was investigated. An external voltage was applied to an adsorbent-coated electrode to examine the adsorption characteristics due to the surface charge. The capability of accepting or providing H+ of the hydroxyl on the adsorbent surface was determined through the titration of NaOH solution, and the change of the hydroxyl before and after adsorption was analyzed by FTIR. Fluoride adsorption was rapid during the initial stage but slowed down later. Fluoride ions were transferred to the adsorbent surface by Coulombic attraction and/or thermal motion, forming a temporary and nonspecific adsorption. The enriched fluoride ions reacted with the hydroxyl groups on the adsorbent surface, forming a stable adsorption. The surface charge on the adsorbent and ion exchange between surface hydroxyl groups and fluoride ions have a large effect on the adsorption rate and efficiency. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800890q
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4530–4534[article] The roles of the surface charge and hydroxyl group on a Fe−Al−Ce adsorbent in fluoride adsorption [texte imprimé] / Hai-Xia Wu, Auteur ; Ting-Jie Wang, Auteur ; Lin Chen, Auteur . - 2009 . - pp. 4530–4534.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4530–4534
Mots-clés : Surface charge Hydroxyl group Fe− Al− Ce adsorbent Fluoride adsorption External voltage Résumé : The roles of the surface charge and hydroxyl group on a Fe−Al−Ce adsorbent in fluoride adsorption were studied. Fluoride adsorption at different initial solution pH was investigated. An external voltage was applied to an adsorbent-coated electrode to examine the adsorption characteristics due to the surface charge. The capability of accepting or providing H+ of the hydroxyl on the adsorbent surface was determined through the titration of NaOH solution, and the change of the hydroxyl before and after adsorption was analyzed by FTIR. Fluoride adsorption was rapid during the initial stage but slowed down later. Fluoride ions were transferred to the adsorbent surface by Coulombic attraction and/or thermal motion, forming a temporary and nonspecific adsorption. The enriched fluoride ions reacted with the hydroxyl groups on the adsorbent surface, forming a stable adsorption. The surface charge on the adsorbent and ion exchange between surface hydroxyl groups and fluoride ions have a large effect on the adsorption rate and efficiency. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800890q Exemplaires
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Titre : Testing and design of a microchannel heat exchanger with multiple plates Type de document : texte imprimé Auteurs : Haishan Cao, Auteur ; Guangwen Chen, Auteur ; Quan Yuan, Auteur Année de publication : 2009 Article en page(s) : pp. 4535–4541 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Microchannel heat exchangers Stainless steel Heat transfer Reynolds number Correlation Résumé : The microheating system is one of the hard cores of a microchemical system. In this paper, the performance of microchannel heat exchangers (MCHEs) with two plates made of stainless steel was investigated experimentally. The maximum volumetric heat transfer coefficient was up to 5.2 MW/m3·K with a corresponding pressure drop of less than 20 kPa under a Reynolds number of around 65. The correlations of average Nusselt number and pressure drop to Reynolds number in microchannels were presented for designing MCHEs with multiple plates with the same geometric structure being researched, and the validity of correlations was verified through MCHEs with two plates and ten plates. Moreover, experimental results verified that MCHEs can be applied to recover energy in integrated microstructure systems of thermal and chemical processes via a system of ethanol dehydration to ethylene. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801419r
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4535–4541[article] Testing and design of a microchannel heat exchanger with multiple plates [texte imprimé] / Haishan Cao, Auteur ; Guangwen Chen, Auteur ; Quan Yuan, Auteur . - 2009 . - pp. 4535–4541.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4535–4541
Mots-clés : Microchannel heat exchangers Stainless steel Heat transfer Reynolds number Correlation Résumé : The microheating system is one of the hard cores of a microchemical system. In this paper, the performance of microchannel heat exchangers (MCHEs) with two plates made of stainless steel was investigated experimentally. The maximum volumetric heat transfer coefficient was up to 5.2 MW/m3·K with a corresponding pressure drop of less than 20 kPa under a Reynolds number of around 65. The correlations of average Nusselt number and pressure drop to Reynolds number in microchannels were presented for designing MCHEs with multiple plates with the same geometric structure being researched, and the validity of correlations was verified through MCHEs with two plates and ten plates. Moreover, experimental results verified that MCHEs can be applied to recover energy in integrated microstructure systems of thermal and chemical processes via a system of ethanol dehydration to ethylene. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801419r Exemplaires
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Titre : Comparative study of CO2 and N2 foams in porous media at low and high pressure-temperatures Type de document : texte imprimé Auteurs : Rouhi Farajzadeh, Auteur ; Alexey Andrianov, Auteur ; Hans Bruining, Auteur Année de publication : 2009 Article en page(s) : pp. 4542–4552 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2 N2 foams Porous media X-ray computed tomography Résumé : We report an experimental study of the behavior of CO2 and N2 foams in granular porous media using X-ray computed tomography. In the experiments either CO2 or N2 gas is forced through natural porous media initially saturated with a surfactant solution, a process known as surfactant-alternating-gas or SAG. The CO2 was either under sub- or supercritical conditions, whereas N2 remained under subcritical conditions at all experimental conditions. We found that CO2 injection following a slug of surfactant can considerably reduce its mobility and promote higher liquid recovery at the experimental conditions investigated. Foaming of CO2 builds-up a lower pressure drop over the core at both low and high pressures than N2. Both gases require space to develop into foam. The space is longer for N2 (larger entrance effect) and increases with increasing gas velocity. Moreover, the ultimate liquid recovery by CO2 foam is always lower than by N2 foam. The possible mechanisms explaining the observed differences in foaming behavior of the two gases are discussed in detail. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801760u
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4542–4552[article] Comparative study of CO2 and N2 foams in porous media at low and high pressure-temperatures [texte imprimé] / Rouhi Farajzadeh, Auteur ; Alexey Andrianov, Auteur ; Hans Bruining, Auteur . - 2009 . - pp. 4542–4552.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4542–4552
Mots-clés : CO2 N2 foams Porous media X-ray computed tomography Résumé : We report an experimental study of the behavior of CO2 and N2 foams in granular porous media using X-ray computed tomography. In the experiments either CO2 or N2 gas is forced through natural porous media initially saturated with a surfactant solution, a process known as surfactant-alternating-gas or SAG. The CO2 was either under sub- or supercritical conditions, whereas N2 remained under subcritical conditions at all experimental conditions. We found that CO2 injection following a slug of surfactant can considerably reduce its mobility and promote higher liquid recovery at the experimental conditions investigated. Foaming of CO2 builds-up a lower pressure drop over the core at both low and high pressures than N2. Both gases require space to develop into foam. The space is longer for N2 (larger entrance effect) and increases with increasing gas velocity. Moreover, the ultimate liquid recovery by CO2 foam is always lower than by N2 foam. The possible mechanisms explaining the observed differences in foaming behavior of the two gases are discussed in detail. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801760u Exemplaires
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Titre : Solubility of CO2 in (water + acetone) : correlation of experimental data and predictions from molecular simulation Type de document : texte imprimé Auteurs : Ilina Urukova, Auteur ; Álvaro Pérez-Salado Kamps, Auteur ; Maurer, Gerd, Auteur Année de publication : 2009 Article en page(s) : pp. 4553–4564 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2--solubility Aqueous solutions Acetone Gibbs ensemble Monte Carlo method Résumé : The correlation and prediction of the solubility of gases in (nonelectrolyte as well as in electrolyte) aqueous/organic solvent mixtures is an important topic in many areas of chemical engineering. Despite the importance of that field, comparatively little attention has been given to that area in both classical thermodynamics (i.e., correlation methods that are based on semiempirical expressions for the excess Gibbs energy) and molecular simulation (where gas solubility can be predicted from intermolecular pair potentials). In the work presented here, recently published experimental data for the solubility of carbon dioxide in aqueous solutions of acetone (covering temperatures from 313 to 395 K at pressures ranging up to about 9 MPa) are used for testing a semiempirical, classical method (for the correlation of such gas solubility phenomena) as well as the Gibbs ensemble Monte Carlo method (GEMC) (for predicting the solubility of carbon dioxide in aqueous solutions of acetone from published intermolecular pair potentials without using any adjustable binary interaction parameter). The correlation method reproduces the experimental data (nearly) within experimental uncertainty, as was expected. The predictions by the GEMC method also agree well with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801015u
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4553–4564[article] Solubility of CO2 in (water + acetone) : correlation of experimental data and predictions from molecular simulation [texte imprimé] / Ilina Urukova, Auteur ; Álvaro Pérez-Salado Kamps, Auteur ; Maurer, Gerd, Auteur . - 2009 . - pp. 4553–4564.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4553–4564
Mots-clés : CO2--solubility Aqueous solutions Acetone Gibbs ensemble Monte Carlo method Résumé : The correlation and prediction of the solubility of gases in (nonelectrolyte as well as in electrolyte) aqueous/organic solvent mixtures is an important topic in many areas of chemical engineering. Despite the importance of that field, comparatively little attention has been given to that area in both classical thermodynamics (i.e., correlation methods that are based on semiempirical expressions for the excess Gibbs energy) and molecular simulation (where gas solubility can be predicted from intermolecular pair potentials). In the work presented here, recently published experimental data for the solubility of carbon dioxide in aqueous solutions of acetone (covering temperatures from 313 to 395 K at pressures ranging up to about 9 MPa) are used for testing a semiempirical, classical method (for the correlation of such gas solubility phenomena) as well as the Gibbs ensemble Monte Carlo method (GEMC) (for predicting the solubility of carbon dioxide in aqueous solutions of acetone from published intermolecular pair potentials without using any adjustable binary interaction parameter). The correlation method reproduces the experimental data (nearly) within experimental uncertainty, as was expected. The predictions by the GEMC method also agree well with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801015u Exemplaires
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Titre : Modeling of the mixed solvent electrolyte system CO2−Na2CO3−NaHCO3−monoethylene glycol−water Type de document : texte imprimé Auteurs : Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur Année de publication : 2009 Article en page(s) : pp. 4565–4578 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolyte system Solid− liquid equilibrium Vapor− liquid CO2− NaHCO3− Na2CO3− monoethylene glycol− H2O electrolyte Résumé : The extended UNIQUAC electrolyte activity coefficient model has been correlated to 751 experimental solid−liquid equilibrium (SLE), vapor−liquid equilibrium (VLE), and excess enthalpy data for the mixed solvent CO2−NaHCO3−Na2CO3−monoethylene glycol(MEG)−H2O electrolyte system. The model was validated by predicting the excess heat capacity. The model is consistent, and one set of binary interaction parameters are used for calculating all the properties between −50 and 90 °C. The model is compared to experimental data of infinite dilution activity coefficient measurements of MEG and may be used for calculating activities, solubility, salt hydrate properties, pH, and CO2 solubility in the NaHCO3−Na2CO3−MEG−H2O system. A simple density model of NaHCO3−Na2CO3−NaCl−MEG−water is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801168e
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4565–4578[article] Modeling of the mixed solvent electrolyte system CO2−Na2CO3−NaHCO3−monoethylene glycol−water [texte imprimé] / Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur . - 2009 . - pp. 4565–4578.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4565–4578
Mots-clés : Electrolyte system Solid− liquid equilibrium Vapor− liquid CO2− NaHCO3− Na2CO3− monoethylene glycol− H2O electrolyte Résumé : The extended UNIQUAC electrolyte activity coefficient model has been correlated to 751 experimental solid−liquid equilibrium (SLE), vapor−liquid equilibrium (VLE), and excess enthalpy data for the mixed solvent CO2−NaHCO3−Na2CO3−monoethylene glycol(MEG)−H2O electrolyte system. The model was validated by predicting the excess heat capacity. The model is consistent, and one set of binary interaction parameters are used for calculating all the properties between −50 and 90 °C. The model is compared to experimental data of infinite dilution activity coefficient measurements of MEG and may be used for calculating activities, solubility, salt hydrate properties, pH, and CO2 solubility in the NaHCO3−Na2CO3−MEG−H2O system. A simple density model of NaHCO3−Na2CO3−NaCl−MEG−water is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801168e Exemplaires
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Titre : Calculation of solid−liquid−gas equilibrium for binary systems containing CO2 Type de document : texte imprimé Auteurs : Jindui Hong, Auteur ; Hui Chen, Auteur ; Jun Li, Auteur Année de publication : 2009 Article en page(s) : pp. 4579–4586 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid− liquid− gas equilibrium Pure-solid vapor pressure Pure-liquid Semipredictive model GE modelsPeng− Robinson EoS Résumé : Two equations typically used for the pure-solid fugacity proved to be identical by selecting an appropriate relation for the pure-solid vapor pressure and the pure-liquid vapor pressure. On the basis of the pure-solid fugacity, a semipredictive model using solubility data (SMS) and a calculation model combining with GE models (CMG) were developed to calculate the solid−liquid−gas (SLG) coexistence lines of pure substances in the presence of CO2. For the SMS model, the Peng−Robinson equation of state (PR-EoS) with the van der Waals one-fluid mixing rule is used to correlate the solute solubility in CO2 to obtain the interaction parameter k12, which is further employed to predict the SLG coexistence lines by two methods: one adopts the fugacity coefficient of the solute in the liquid phase by an equation of state calculation (SMS-φ); the other uses the activity coefficient of the solute in the liquid phase calculated from the UNIFAC model (SMS-γ). For the CMG model, the PR-EoS with the linear combination of Vidal and Michelsen (LCVM) mixing rule, the Michelsen modified Huron-Vidal (MHV1) mixing rule, and a modified version (mLCVM) with the re-evaluated parameter λ = 0.18 are used. Results show that the SMS model can provide acceptable calculations of the SLG coexistence lines for most of the investigated systems. The predicted melting temperatures and solute compositions in liquid phase from a constant k12 are slightly better than those from the correlated one, while the predicted solute solubility data in CO2 from a constant k12 are worse than those from the correlated one. The CMG model with the mLCVM mixing rule calculates well the melting temperatures and solute compositions in liquid phase at SLG equilibrium and also gives acceptable calculations of the solute solubilities in supercritical CO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801179a
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4579–4586[article] Calculation of solid−liquid−gas equilibrium for binary systems containing CO2 [texte imprimé] / Jindui Hong, Auteur ; Hui Chen, Auteur ; Jun Li, Auteur . - 2009 . - pp. 4579–4586.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4579–4586
Mots-clés : Solid− liquid− gas equilibrium Pure-solid vapor pressure Pure-liquid Semipredictive model GE modelsPeng− Robinson EoS Résumé : Two equations typically used for the pure-solid fugacity proved to be identical by selecting an appropriate relation for the pure-solid vapor pressure and the pure-liquid vapor pressure. On the basis of the pure-solid fugacity, a semipredictive model using solubility data (SMS) and a calculation model combining with GE models (CMG) were developed to calculate the solid−liquid−gas (SLG) coexistence lines of pure substances in the presence of CO2. For the SMS model, the Peng−Robinson equation of state (PR-EoS) with the van der Waals one-fluid mixing rule is used to correlate the solute solubility in CO2 to obtain the interaction parameter k12, which is further employed to predict the SLG coexistence lines by two methods: one adopts the fugacity coefficient of the solute in the liquid phase by an equation of state calculation (SMS-φ); the other uses the activity coefficient of the solute in the liquid phase calculated from the UNIFAC model (SMS-γ). For the CMG model, the PR-EoS with the linear combination of Vidal and Michelsen (LCVM) mixing rule, the Michelsen modified Huron-Vidal (MHV1) mixing rule, and a modified version (mLCVM) with the re-evaluated parameter λ = 0.18 are used. Results show that the SMS model can provide acceptable calculations of the SLG coexistence lines for most of the investigated systems. The predicted melting temperatures and solute compositions in liquid phase from a constant k12 are slightly better than those from the correlated one, while the predicted solute solubility data in CO2 from a constant k12 are worse than those from the correlated one. The CMG model with the mLCVM mixing rule calculates well the melting temperatures and solute compositions in liquid phase at SLG equilibrium and also gives acceptable calculations of the solute solubilities in supercritical CO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801179a Exemplaires
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Titre : Hydrothermal pretreatment of rubber wood for the saccharification process Type de document : texte imprimé Auteurs : Phacharakamol Petchpradab, Auteur ; Takuya Yoshida, Auteur ; Tawatchai Charinpanitkul, Auteur Année de publication : 2009 Article en page(s) : pp. 4587–4591 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Rubber wood Hydrothermal pretreatmentEnzymatic hydrolysis Résumé : Rubber wood (Hevea brasiliensis) was employed as a biomass raw material for the hydrothermal pretreatment process for the enzymatic hydrolysis. Pulverized rubber wood was treated at 130−280 °C using an autoclave with inner volume of 96 cm3. The glucose content of the treated liquid product was measured. The solid product was analyzed for cellulose content and further treated with cellulase. The product glucose yield indicated the effectiveness of the hydrothermal pretreatment. A reaction network model for the hydrothermal pretreatment was proposed and applied successfully. The reaction parameters were determined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801314h
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4587–4591[article] Hydrothermal pretreatment of rubber wood for the saccharification process [texte imprimé] / Phacharakamol Petchpradab, Auteur ; Takuya Yoshida, Auteur ; Tawatchai Charinpanitkul, Auteur . - 2009 . - pp. 4587–4591.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4587–4591
Mots-clés : Rubber wood Hydrothermal pretreatmentEnzymatic hydrolysis Résumé : Rubber wood (Hevea brasiliensis) was employed as a biomass raw material for the hydrothermal pretreatment process for the enzymatic hydrolysis. Pulverized rubber wood was treated at 130−280 °C using an autoclave with inner volume of 96 cm3. The glucose content of the treated liquid product was measured. The solid product was analyzed for cellulose content and further treated with cellulase. The product glucose yield indicated the effectiveness of the hydrothermal pretreatment. A reaction network model for the hydrothermal pretreatment was proposed and applied successfully. The reaction parameters were determined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801314h Exemplaires
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Titre : Solid−liquid circulating multistage fluidized bed : hydrodynamic study Type de document : texte imprimé Auteurs : Prakash V Chavan, Auteur ; Dinesh V Kalaga, Auteur ; Jyeshtharaj B. Joshi, Auteur Année de publication : 2009 Article en page(s) : pp. 4592–4602 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid− liquid circulating multistage fluidized bed Riser column Multistage WaterIon-exchange Résumé : The solid−liquid circulating multistage fluidized bed (SLCMFB) was constructed with the principal components being the riser column and the multistage column. The riser column was made up of 50 mm i.d. and 2 m long glass pipe while the multistage column was made up of seven glass stages of 100 mm i.d. and 100 mm length. The ion-exchange resin was used as solid phase and water as fluidizing medium. The flow characteristics of SLCMFB were investigated for 0.365, 0.605, and 0.725 mm particle sizes (dry basis). The voidage in the riser and multistage column was measured using γ-ray tomography (GRT). In the riser column, the voidage was found to be maximum at the center and minimum near the wall. However, in the multistage column, voidage was found to be uniform over cross section of the column. The solid particle velocity was measured using ultrasonic velocity profiler (UVP) in the riser column. The particle velocity profiles show similar trend as the voidage, confirming the existence of the radial non-uniformity in the riser column. Further, the non-uniformity was analyzed using the drift flux model (DFM) and the effect of particle size and superficial liquid velocity on the non-uniformity was also investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018627
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4592–4602[article] Solid−liquid circulating multistage fluidized bed : hydrodynamic study [texte imprimé] / Prakash V Chavan, Auteur ; Dinesh V Kalaga, Auteur ; Jyeshtharaj B. Joshi, Auteur . - 2009 . - pp. 4592–4602.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4592–4602
Mots-clés : Solid− liquid circulating multistage fluidized bed Riser column Multistage WaterIon-exchange Résumé : The solid−liquid circulating multistage fluidized bed (SLCMFB) was constructed with the principal components being the riser column and the multistage column. The riser column was made up of 50 mm i.d. and 2 m long glass pipe while the multistage column was made up of seven glass stages of 100 mm i.d. and 100 mm length. The ion-exchange resin was used as solid phase and water as fluidizing medium. The flow characteristics of SLCMFB were investigated for 0.365, 0.605, and 0.725 mm particle sizes (dry basis). The voidage in the riser and multistage column was measured using γ-ray tomography (GRT). In the riser column, the voidage was found to be maximum at the center and minimum near the wall. However, in the multistage column, voidage was found to be uniform over cross section of the column. The solid particle velocity was measured using ultrasonic velocity profiler (UVP) in the riser column. The particle velocity profiles show similar trend as the voidage, confirming the existence of the radial non-uniformity in the riser column. Further, the non-uniformity was analyzed using the drift flux model (DFM) and the effect of particle size and superficial liquid velocity on the non-uniformity was also investigated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8018627 Exemplaires
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Titre : Vapor pressures of polymer solutions and the modeling of their composition dependence Type de document : texte imprimé Auteurs : Maria Bercea, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur Année de publication : 2009 Article en page(s) : pp. 4603–4606 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Vapor pressures Poly(vinyl methyl ether) Polystyrene Tetrahydrofuran Résumé : Equilibrium vapor pressures, p, are reported for the systems tetrahydrofuran + poly(vinyl methyl ether) and tetrahydrofuran + polystyrene at 20, 40, and 60 °C. These data plus information from the literature serve to demonstrate that the composition dependence of p can be modeled quantitatively for polymer solutions in thermodynamically very different solvents by means of three, physically meaningful parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801965h
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4603–4606[article] Vapor pressures of polymer solutions and the modeling of their composition dependence [texte imprimé] / Maria Bercea, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur . - 2009 . - pp. 4603–4606.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4603–4606
Mots-clés : Vapor pressures Poly(vinyl methyl ether) Polystyrene Tetrahydrofuran Résumé : Equilibrium vapor pressures, p, are reported for the systems tetrahydrofuran + poly(vinyl methyl ether) and tetrahydrofuran + polystyrene at 20, 40, and 60 °C. These data plus information from the literature serve to demonstrate that the composition dependence of p can be modeled quantitatively for polymer solutions in thermodynamically very different solvents by means of three, physically meaningful parameters. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801965h Exemplaires
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Titre : Effect of “free” cation substituent on gas separation performance of polymer−room-temperature Ionic liquid composite membranes Type de document : texte imprimé Auteurs : Jason E. Bara, Auteur ; Richard D. Noble, Auteur ; Douglas L. Gin, Auteur Année de publication : 2009 Article en page(s) : pp. 4607–4610 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Room-temperature ionic liquid Imidazolium cation poly(RTIL) matrix Résumé : Room-temperature ionic liquid (RTIL) based monomers were photopolymerized in the presence of nonpolymerizable RTILs with various types of organic functional groups attached to the imidazolium cation. Groups employed include alkyl, ether, nitrile, fluoroalkyl, and siloxane functionalities. This straightforward method allows for a broad range of functional groups to be incorporated into poly(RTIL) matrices without the need to develop new monomers. The resultant poly(RTIL)−RTIL composites were homogeneous, optically transparent solids that exhibited no signs of phase separation, even after many months of storage. As thin films, poly(RTIL)−RTIL composites were utilized as gas separation membranes and tested for their permeabilities to CO2, N2, and CH4. The presence of 20 mol % “free” RTIL within the poly(RTIL) matrix was shown to increase CO2 permeability by ∼100−250% relative to the neat poly(RTIL) membrane with no free RTIL component. The nature of the organic functional group associated with the free RTIL cation can influence both gas permeability and CO2/N2 and CO2/CH4 selectivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801897r
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4607–4610[article] Effect of “free” cation substituent on gas separation performance of polymer−room-temperature Ionic liquid composite membranes [texte imprimé] / Jason E. Bara, Auteur ; Richard D. Noble, Auteur ; Douglas L. Gin, Auteur . - 2009 . - pp. 4607–4610.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4607–4610
Mots-clés : Room-temperature ionic liquid Imidazolium cation poly(RTIL) matrix Résumé : Room-temperature ionic liquid (RTIL) based monomers were photopolymerized in the presence of nonpolymerizable RTILs with various types of organic functional groups attached to the imidazolium cation. Groups employed include alkyl, ether, nitrile, fluoroalkyl, and siloxane functionalities. This straightforward method allows for a broad range of functional groups to be incorporated into poly(RTIL) matrices without the need to develop new monomers. The resultant poly(RTIL)−RTIL composites were homogeneous, optically transparent solids that exhibited no signs of phase separation, even after many months of storage. As thin films, poly(RTIL)−RTIL composites were utilized as gas separation membranes and tested for their permeabilities to CO2, N2, and CH4. The presence of 20 mol % “free” RTIL within the poly(RTIL) matrix was shown to increase CO2 permeability by ∼100−250% relative to the neat poly(RTIL) membrane with no free RTIL component. The nature of the organic functional group associated with the free RTIL cation can influence both gas permeability and CO2/N2 and CO2/CH4 selectivity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801897r Exemplaires
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Titre : Constrained inverse fluidization of light particles in a draft tube airlift reactor Type de document : texte imprimé Auteurs : Ivana M. Šijacki, Auteur ; Radmilo R. Colovic, Auteur ; Bojan Petkovic, Auteur Année de publication : 2009 Article en page(s) : pp. 4611–4618 Note générale : Chemical enginerring Langues : Anglais (eng) Mots-clés : Inverse fluidized bed Draft tube airlift reactor Liquid phase Aqueous solution Résumé : The objective of this work was to investigate the main fluidodynamic behavior of a constrained inverse fluidized bed in a draft tube airlift reactor (DT-ALR), with liquid in batch and air in continuous mode. The inverse fluidized bed was formed of relatively large particles (4.3−5.4 mm) that were composed of light polyethylene (PE), in the first case, and of particles (3.7−4.7 mm) that were composed of extremely light polystyrene (PS), in the second case. The influence of physical properties of liquid phase (surface tension and viscosity) on basic fluidodynamic characteristics was examined using the coalescence-inhibiting medium (1 wt % aqueous solution of ethanol) and viscous medium (46 wt % aqueous solution of sucrose). It is shown that the overall gas holdup, induced liquid velocity, minimum fluidization velocity, and bed expansion are dependent on the superficial gas velocity and liquid and solid properties. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801915m
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4611–4618[article] Constrained inverse fluidization of light particles in a draft tube airlift reactor [texte imprimé] / Ivana M. Šijacki, Auteur ; Radmilo R. Colovic, Auteur ; Bojan Petkovic, Auteur . - 2009 . - pp. 4611–4618.
Chemical enginerring
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4611–4618
Mots-clés : Inverse fluidized bed Draft tube airlift reactor Liquid phase Aqueous solution Résumé : The objective of this work was to investigate the main fluidodynamic behavior of a constrained inverse fluidized bed in a draft tube airlift reactor (DT-ALR), with liquid in batch and air in continuous mode. The inverse fluidized bed was formed of relatively large particles (4.3−5.4 mm) that were composed of light polyethylene (PE), in the first case, and of particles (3.7−4.7 mm) that were composed of extremely light polystyrene (PS), in the second case. The influence of physical properties of liquid phase (surface tension and viscosity) on basic fluidodynamic characteristics was examined using the coalescence-inhibiting medium (1 wt % aqueous solution of ethanol) and viscous medium (46 wt % aqueous solution of sucrose). It is shown that the overall gas holdup, induced liquid velocity, minimum fluidization velocity, and bed expansion are dependent on the superficial gas velocity and liquid and solid properties. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801915m Exemplaires
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