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Adsorption and photocatalytic degradation kinetics of gaseous cyclohexane in an annular fluidized bed photocatalytic reactor / Qijin Geng in Industrial & engineering chemistry research, Vol. 49 N° 10 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4644–4652 Titre : Adsorption and photocatalytic degradation kinetics of gaseous cyclohexane in an annular fluidized bed photocatalytic reactor Type de document : texte imprimé Auteurs : Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Xuehai Yue, Auteur Année de publication : 2010 Article en page(s) : pp. 4644–4652 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetics  Photocatalytic Résumé : The adsorption and photocatalytic degradation kinetics of gaseous cyclohexane using nano-titania agglomerates were investigated in an annular fluidized bed photocatalytic reactor (AFBPR). A series of adsorption and photocatalytic degradation kinetic equations were developed to explore the relationship of adsorption/degradation efficiency and operating variables based on Langmuir adsorption law and photocatalytic elementary reactions. The adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of cyclohexane were determined by linear regression analysis with variation of gas velocity and relative humidity (RH). It has been demonstrated that the initial concentration, RH, and gas velocity have obviously influenced the adsorption/photocatalytic degradation efficiency and corresponding kinetic parameters. In the adsorption process, the variation of adsorption sites and adsorption efficiency with gas velocity indicated that the adsorption controlling step was related to gas velocity. In the photocatalytic degradation process, the relationship of photocatalytic degradation efficiency and RH indicates that the water molecule played a promotion role in photocatalytic degradation of cyclohexane below a humidity inflection point, while it played an inhibition role in photocatalytic degradation of cyclohexane after this point. In addition, the optimal operating conditions were determined according to the maximum degradation efficiency with respect to RH at 20% and the fluidization number at 1.62. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100114e [article] Adsorption and photocatalytic degradation kinetics of gaseous cyclohexane in an annular fluidized bed photocatalytic reactor [texte imprimé] / Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Xuehai Yue, Auteur . - 2010 . - pp. 4644–4652. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4644–4652 Mots-clés : Kinetics  Photocatalytic Résumé : The adsorption and photocatalytic degradation kinetics of gaseous cyclohexane using nano-titania agglomerates were investigated in an annular fluidized bed photocatalytic reactor (AFBPR). A series of adsorption and photocatalytic degradation kinetic equations were developed to explore the relationship of adsorption/degradation efficiency and operating variables based on Langmuir adsorption law and photocatalytic elementary reactions. The adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of cyclohexane were determined by linear regression analysis with variation of gas velocity and relative humidity (RH). It has been demonstrated that the initial concentration, RH, and gas velocity have obviously influenced the adsorption/photocatalytic degradation efficiency and corresponding kinetic parameters. In the adsorption process, the variation of adsorption sites and adsorption efficiency with gas velocity indicated that the adsorption controlling step was related to gas velocity. In the photocatalytic degradation process, the relationship of photocatalytic degradation efficiency and RH indicates that the water molecule played a promotion role in photocatalytic degradation of cyclohexane below a humidity inflection point, while it played an inhibition role in photocatalytic degradation of cyclohexane after this point. In addition, the optimal operating conditions were determined according to the maximum degradation efficiency with respect to RH at 20% and the fluidization number at 1.62. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100114e

Adsorption and photocatalytic degradation of reactive brilliant red K - 2BP by TiO2/AC in bubbling fluidized bed photocatalytic reactor / Qijin Geng in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11321-11330 Titre : Adsorption and photocatalytic degradation of reactive brilliant red K - 2BP by TiO2/AC in bubbling fluidized bed photocatalytic reactor Type de document : texte imprimé Auteurs : Qijin Geng, Auteur ; Wenwen Cui, Auteur Année de publication : 2011 Article en page(s) : pp. 11321-11330 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photocatalysis  Photochemical  reactor  Catalytic  reactor  Fluidized  bed  Fluidization  Bubbling  Titanium  oxide  Photochemical  degradation  Adsorption Résumé : An activated carbon-supported titanium dioxide photocatalyst (TiO2/AC) was prepared by a spinning coating method and applied in a designed bubbling fluidized bed photocatalytic reactor (BFBPR). Adsorption and photocatalytic degradation of reactive brilliant red K-2BP in BFBPR were investigated considering the pH value, Na2SO4 added, and initial dye concentration. The experimental results indicated that the adsorption and photocatalytic degradation efficiencies of K-2BP were influenced by the pH value, Na2SO4 added, and initial dye concentration. The adsorption and photocatalytic degradation of K-2BP was approximated to the maximum value at pH value 5.7. The complex influence of Na2SO4 added on photocatalytic degradation of K-2BP at alkaline suspension was observed and explained according to the adsorption models proposed and degradation mechanism of a new free radical (SO4•−) produced. In addition, the presence of Na2SO4 plays dual functions, i.e., salt bridge-role in adsorption for Na+ and competition adsorption between anion dye molecules and SO42−, conformed by adsorption models proposed and FT-IR spectra for dye adsorption on TiO2/AC. The mass-transfer limited and screening effect that resulted from variation of the initial dye concentration may be approximated to the minimum effect at concentration of 3.75 mg L−1, with the maximum degradation efficiency above 80%. The Langmuir−Hinshelwood kinetic model was applied to explore the adsorption and degradation. Finally, the special reaction paths were inferred with variation of experimental environments. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437828 [article] Adsorption and photocatalytic degradation of reactive brilliant red K - 2BP by TiO2/AC in bubbling fluidized bed photocatalytic reactor [texte imprimé] / Qijin Geng, Auteur ; Wenwen Cui, Auteur . - 2011 . - pp. 11321-11330. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11321-11330 Mots-clés : Photocatalysis  Photochemical  reactor  Catalytic  reactor  Fluidized  bed  Fluidization  Bubbling  Titanium  oxide  Photochemical  degradation  Adsorption Résumé : An activated carbon-supported titanium dioxide photocatalyst (TiO2/AC) was prepared by a spinning coating method and applied in a designed bubbling fluidized bed photocatalytic reactor (BFBPR). Adsorption and photocatalytic degradation of reactive brilliant red K-2BP in BFBPR were investigated considering the pH value, Na2SO4 added, and initial dye concentration. The experimental results indicated that the adsorption and photocatalytic degradation efficiencies of K-2BP were influenced by the pH value, Na2SO4 added, and initial dye concentration. The adsorption and photocatalytic degradation of K-2BP was approximated to the maximum value at pH value 5.7. The complex influence of Na2SO4 added on photocatalytic degradation of K-2BP at alkaline suspension was observed and explained according to the adsorption models proposed and degradation mechanism of a new free radical (SO4•−) produced. In addition, the presence of Na2SO4 plays dual functions, i.e., salt bridge-role in adsorption for Na+ and competition adsorption between anion dye molecules and SO42−, conformed by adsorption models proposed and FT-IR spectra for dye adsorption on TiO2/AC. The mass-transfer limited and screening effect that resulted from variation of the initial dye concentration may be approximated to the minimum effect at concentration of 3.75 mg L−1, with the maximum degradation efficiency above 80%. The Langmuir−Hinshelwood kinetic model was applied to explore the adsorption and degradation. Finally, the special reaction paths were inferred with variation of experimental environments. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437828

Hydrodynamics and axial dispersion in a gas−liquid−(solid) EL-ALR with different sparger designs / Changqing Cao in Industrial & engineering chemistry research, Vol. 47 n°11 (Juin 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°11 (Juin 2008) . - p. 4008–4017 Titre : Hydrodynamics and axial dispersion in a gas−liquid−(solid) EL-ALR with different sparger designs Type de document : texte imprimé Auteurs : Changqing Cao, Auteur ; Shuqin Dong, Auteur ; Qijin Geng, Auteur ; Qingjie Guo, Auteur Année de publication : 2008 Article en page(s) : p. 4008–4017 Note générale : Bibliogr. p. 4017 Langues : Anglais (eng) Mots-clés : Gs−liquid−(solid);  External-loop  airlift  reactor Résumé : The gas−liquid−(solid) three-phase hydrodynamics in an external-loop airlift reactor (EL-ALR) with an upward pipe 0.47 m in diameter and 2.5 m in height, two external loop downward pipes 0.08 m in diameter and 2.5 m in height, were investigated using four different gas sparger designs. The microconductivity probe and the three-dimensional (3-D) laser Doppler anemometry (LDA) techniques were, respectively, implemented to measure the local gas holdup in the riser (αGr) and liquid phase velocity in the downcomer (ULd) using air as the gas phase, water as the liquid phase, and alginate gel beads as the solid phase, over a wide range of operation conditions. The tracer age distribution was measured using the pulse-pursuit response technology. Axial dispersion model (ADM) was used to estimate the model parameter Peclet number (Pe) values as a fitted parameter with the measured data, using the gold partition method for nonlinear programming strategy inequation restrict conditions. The ADM gave better fits to the experimental data at high axial locations and lower superficial gas velocity (UG) for an EL-ALR used with a large L/DR ratio. A synergistic effect of ULd, αGr, Pe, solids loading (SL), and sparger designs on the performance of an EL-ALR was observed in our experiments. The sparger designs were determined to have a noticeable effect on the αGr and Pe in the lower gas velocity and lower solid loading ranges (UG < 0.025 m/s and SL < 2%), but only a slight effect in the high gas velocity and high solid loading ranges (UG > 0.030 m/s and SL > 3%). However, the effect of sparger designs on the ULd is greater in the gas velocity from 0.025 m/s to 0.045 m/s. For the lower solids loading, the increase of orifice diameter leads to a decrease in αGr. This is in accordance with what was presented in the gas−liquid two-phase system. Moreover, the influence of orifice diameters of the spargers is negligible for solids loading of >3%. Although the Pe values decreased with the operating gas velocity, the gas velocity change from 0.03 m/s to 0.04 m/s yielded lower Pe values, as a result of the reduced bubble size. As the gas velocity further increased to 0.06 m/s, the αGr and the ULd values increased, while the Pe values negligibly increased. For a gas−liquid two-phase system, Pe decreases with the orifice diameter and, for 1% of solids, Pe is also lower for sparger P-2 (ϕ 0.6 mm) than for sparger P-1 (ϕ 0.3 mm). For higher amounts of solids (3%), Pe does not have a defined trend. In addition to the gas velocity and sparger design effects, the solids loading had the effect of decreasing the ULd values, while such effect became small and flattened at high solid loadings. The ULd values, especially with VO = 100%, are ~20% lower in three-phase flow than that in two-phase flow. In addition, the ULd profiles in three-phase flow are flatter than that in two-phase flow with VO = 50%−100%, actually showing a parabolic shape rather than the almost linear one encountered in two-phase flow. This is very important for design and optimum operation that are used to systemically investigate the synergistic effect of ULd, αGr, Pe, solid loading (SL), and sparger designs on hydrodynamic performance of an EL-ALR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715254 [article] Hydrodynamics and axial dispersion in a gas−liquid−(solid) EL-ALR with different sparger designs [texte imprimé] / Changqing Cao, Auteur ; Shuqin Dong, Auteur ; Qijin Geng, Auteur ; Qingjie Guo, Auteur . - 2008 . - p. 4008–4017. Bibliogr. p. 4017 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°11 (Juin 2008) . - p. 4008–4017 Mots-clés : Gs−liquid−(solid);  External-loop  airlift  reactor Résumé : The gas−liquid−(solid) three-phase hydrodynamics in an external-loop airlift reactor (EL-ALR) with an upward pipe 0.47 m in diameter and 2.5 m in height, two external loop downward pipes 0.08 m in diameter and 2.5 m in height, were investigated using four different gas sparger designs. The microconductivity probe and the three-dimensional (3-D) laser Doppler anemometry (LDA) techniques were, respectively, implemented to measure the local gas holdup in the riser (αGr) and liquid phase velocity in the downcomer (ULd) using air as the gas phase, water as the liquid phase, and alginate gel beads as the solid phase, over a wide range of operation conditions. The tracer age distribution was measured using the pulse-pursuit response technology. Axial dispersion model (ADM) was used to estimate the model parameter Peclet number (Pe) values as a fitted parameter with the measured data, using the gold partition method for nonlinear programming strategy inequation restrict conditions. The ADM gave better fits to the experimental data at high axial locations and lower superficial gas velocity (UG) for an EL-ALR used with a large L/DR ratio. A synergistic effect of ULd, αGr, Pe, solids loading (SL), and sparger designs on the performance of an EL-ALR was observed in our experiments. The sparger designs were determined to have a noticeable effect on the αGr and Pe in the lower gas velocity and lower solid loading ranges (UG < 0.025 m/s and SL < 2%), but only a slight effect in the high gas velocity and high solid loading ranges (UG > 0.030 m/s and SL > 3%). However, the effect of sparger designs on the ULd is greater in the gas velocity from 0.025 m/s to 0.045 m/s. For the lower solids loading, the increase of orifice diameter leads to a decrease in αGr. This is in accordance with what was presented in the gas−liquid two-phase system. Moreover, the influence of orifice diameters of the spargers is negligible for solids loading of >3%. Although the Pe values decreased with the operating gas velocity, the gas velocity change from 0.03 m/s to 0.04 m/s yielded lower Pe values, as a result of the reduced bubble size. As the gas velocity further increased to 0.06 m/s, the αGr and the ULd values increased, while the Pe values negligibly increased. For a gas−liquid two-phase system, Pe decreases with the orifice diameter and, for 1% of solids, Pe is also lower for sparger P-2 (ϕ 0.6 mm) than for sparger P-1 (ϕ 0.3 mm). For higher amounts of solids (3%), Pe does not have a defined trend. In addition to the gas velocity and sparger design effects, the solids loading had the effect of decreasing the ULd values, while such effect became small and flattened at high solid loadings. The ULd values, especially with VO = 100%, are ~20% lower in three-phase flow than that in two-phase flow. In addition, the ULd profiles in three-phase flow are flatter than that in two-phase flow with VO = 50%−100%, actually showing a parabolic shape rather than the almost linear one encountered in two-phase flow. This is very important for design and optimum operation that are used to systemically investigate the synergistic effect of ULd, αGr, Pe, solid loading (SL), and sparger designs on hydrodynamic performance of an EL-ALR. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715254

Investigation into photocatalytic degradation of gaseous ammonia in CPCR / Qijin Geng in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4363–4368 Titre : Investigation into photocatalytic degradation of gaseous ammonia in CPCR Type de document : texte imprimé Auteurs : Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Changqing Cao, Auteur ; Yunchen Zhang, Auteur Année de publication : 2008 Article en page(s) : p. 4363–4368 Note générale : Bibliogr. p. 4368 Langues : Anglais (eng) Mots-clés : Ammonia;  Circulated  photocatalytic  reactor;  Photocatalytic  degradation Résumé : Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution because of continuous transformation and emission of urea to gaseous ammonia on indoor concrete walls. To control ammonia pollution from indoor concrete walls, a circulated photocatalytic reactor (CPCR) was designed to intensify the performance for the decomposition of gaseous ammonia in the present study and TiO2 film photocatalysts were prepared by the sol−gel method and coating onto the inner wall of this reactor using a bonder of polyacrylic ester emulsion, which was characterized by FTIR, TEM, and SEM. In particular, the influences of initial concentration of ammonia on the degradation conversion (Dp), apparent reaction rate constants (kr), initial degradation rate (r), deactivation, and regeneration of catalyst in CPCR were investigated. Furthermore, a designed equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in CPCR. The total number of adsorption sites available for the gas molecules NT and the adsorption equilibrium constant Kads values were determined through a linear-fitting method. Finally, undesirable NO2− and NO3− were detected as the intermediates in the process of photodegradation at different initial concentration of ammonia, which was detected by catalytic kinetic spectrophotometry. The results indicated that the degradation conversion (Dp), initial degradation rate (r), degraded products, and half-life (t1/2) were closely correlated to the initial concentration of ammonia. It was found that the reaction kinetics fixed the pseudofirst-order kinetic equation of photocatalytic degradation of gaseous ammonia in CPCR, and the kinetic results are discussed in terms of adsorption of ammonia and products degraded. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800274g [article] Investigation into photocatalytic degradation of gaseous ammonia in CPCR [texte imprimé] / Qijin Geng, Auteur ; Qingjie Guo, Auteur ; Changqing Cao, Auteur ; Yunchen Zhang, Auteur . - 2008 . - p. 4363–4368. Bibliogr. p. 4368 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4363–4368 Mots-clés : Ammonia;  Circulated  photocatalytic  reactor;  Photocatalytic  degradation Résumé : Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution because of continuous transformation and emission of urea to gaseous ammonia on indoor concrete walls. To control ammonia pollution from indoor concrete walls, a circulated photocatalytic reactor (CPCR) was designed to intensify the performance for the decomposition of gaseous ammonia in the present study and TiO2 film photocatalysts were prepared by the sol−gel method and coating onto the inner wall of this reactor using a bonder of polyacrylic ester emulsion, which was characterized by FTIR, TEM, and SEM. In particular, the influences of initial concentration of ammonia on the degradation conversion (Dp), apparent reaction rate constants (kr), initial degradation rate (r), deactivation, and regeneration of catalyst in CPCR were investigated. Furthermore, a designed equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in CPCR. The total number of adsorption sites available for the gas molecules NT and the adsorption equilibrium constant Kads values were determined through a linear-fitting method. Finally, undesirable NO2− and NO3− were detected as the intermediates in the process of photodegradation at different initial concentration of ammonia, which was detected by catalytic kinetic spectrophotometry. The results indicated that the degradation conversion (Dp), initial degradation rate (r), degraded products, and half-life (t1/2) were closely correlated to the initial concentration of ammonia. It was found that the reaction kinetics fixed the pseudofirst-order kinetic equation of photocatalytic degradation of gaseous ammonia in CPCR, and the kinetic results are discussed in terms of adsorption of ammonia and products degraded. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800274g