The Experts below are selected from a list of 42921 Experts worldwide ranked by ideXlab platform
Xiaoqing Lin - One of the best experts on this subject based on the ideXlab platform.
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adsorption isotherm kinetics simulation and breakthrough analysis of 5 hydroxymethylfurfural adsorption desorption behavior of a novel polar modified post cross linked poly divinylbenzene co ethyleneglycoldimethacrylate resin
Chemosphere, 2020Co-Authors: Jiayi Zheng, Chiliu Cai, Jiangxiong Xiao, Yao Liu, Zhe Chen, Baoying Pan, Xiaoqing LinAbstract:Abstract A polar modified post-cross-linked poly (divinylbenzene-co-ethyleneglycol-dimethacrylate) (PCL-PDE) resin was synthesized by suspension polymerization of ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB), and a post-cross-linked reaction. After characterization, the adsorption behaviors of 5-hydroxymethylfurfural (5-HMF) on PCL-PDE resin were determined in comparison with the starting copolymers PDE resin. The equilibrium adsorption capacity of 5-HMF on PCL-PDE resin was much larger than PDE resin and the increase rate was greater than 52.6%. The equilibrium data of 5-HMF onto PCL-PDE resin were found to be better fitted by the Langmuir isotherm model. The kinetic data shows that the adsorption reached equilibrium in a short time (less than 20 min) can be fitted by the Pore Diffusion model (PDM) at various operating conditions. The effective Pore Diffusion coefficient was dependent upon adsorption temperature, and were 6.706 × 10−10, 8.958 × 10−10, 1.136 × 10−9 and 1.429 × 10−9 m2 s−1 at 288, 298, 308 and 318 K, respectively. Furthermore, the effects of feed flow rate (Qf = 0.6, 1.5, 3.0 and 6.0 mL min−1) and initial 5-HMF concentration (cf = 0.52, 1.02, 2.00 and 4.96 g L−1) on the adsorption were investigated systematically. Besides, a general rate model (GRM) was used to predict adsorption breakthrough curves of 5-HMF. The simulation results are highly consistent with the experimental data, indicating that the GRM can successfully simulate this process. In the desorption process, the desorption capacity reaches 99.6% of adsorbed capacity, suggesting that the PCL-PDE resin exhibited good reusability. Therefore, it could be suggested that the PCL-PDE resin has a potential application in the separation and purification of 5-HMF.
Gordon Mckay - One of the best experts on this subject based on the ideXlab platform.
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empirical multicomponent equilibrium and film Pore model for the sorption of copper cadmium and zinc onto bone char
Adsorption-journal of The International Adsorption Society, 2005Co-Authors: Chun Wai Cheung, John F Porter, Keith K H Choy, Gordon MckayAbstract:The adsorption of three metal ions onto bone char has been studied in both equilibrium and kinetic systems. An empirical Langmuir-type equation has been proposed to correlate the experimental equilibrium data for multicomponent systems. The sorption equilibrium of three metal ions, namely, cadmium (II) ion, zinc (II) ion and copper (II) ion in the three binary and one ternary systems is well correlated by the Langmuir-type equation. For the batch kinetic studies, a multicomponent film-Pore Diffusion model was developed by incorporating this empirical Langmuir-type equation into a single component film-Pore Diffusion model and was used to correlate the multicomponent batch kinetic data. The multicomponent film-Pore Diffusion model shows some deviation from the experimental data for the sorption of cadmium ions in Cd-Cu, Cd-Zn and Cd-Cu-Zn systems. However, overall this model gives a good correlation of the experimental data for three binary and one ternary systems.
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Film-Pore Diffusion model for the fixed-bed sorption of copper and cadmium ions onto bone char.
Water Research, 2001Co-Authors: John F Porter, Gordon MckayAbstract:Abstract The sorption of copper and cadmium ions onto bone char in single component systems has been studied using fixed-bed column adsorbers. The effects of solution flowrate, initial metal ion concentration and bone char particle size have been studied. A film-Pore Diffusion model has been developed to predict the fixed-bed breakthrough curves for the two metal ions. A sensitivity analysis has been carried out to investigate the influence of the external mass transfer coefficient (film resistance), the effective Diffusion coefficient (Pore Diffusion) and the solid phase loading capacity. It is found that under the experimental conditions employed in the study, film Diffusional resistance was low and the Biot numbers were relatively high. Furthermore, a constant effective Pore diffusivity was not sufficient to correlate the breakthrough curves accurately and a variable dependent effective diffusivity was required; suggesting a possible contribution from surface Diffusion. Since the metal ion–bone char systems take a long time to reach equilibrium, the solid phase loading capacity, as predicted by the “best-fit” equilibrium isotherm, was not suitable for use in the Diffusional mass transport model and the mass balance solid phase loading was utilised instead.
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film Pore Diffusion modeling and contact time optimization for the adsorption of dyestuffs on pith
Chemical Engineering Journal, 2001Co-Authors: Buning Chen, Chi Wai Hui, Gordon MckayAbstract:Abstract The sorption of four dyestuffs, namely, Acid Blue 25 (AB25), Acid Red 114 (AR114), Basic Blue 69 (BB69) and Basic Red 22 (BR22) onto bagasse pith has been studied using an agitated batch sorber system. The equilibrium isotherms were determined and kinetic runs were performed over a range of concentrations for each dye and masses of pith. A film-Pore Diffusion mass transfer model has been developed based on a single effective Diffusion coefficient for each system. Error analysis of the experimental and theoretical data indicated relatively large errors at low initial dyestuff concentrations. In this paper, a contact time optimization methodology of a two-stage batch adsorber system taking minimum contact time as the objective function has been developed. The initial concentration of the second stage and adsorbent weight have been designated as variables. Contact time optimization of a two-stage batch adsorber system has been demonstrated at two different conditions/cases for the adsorption of dyes on pith. The optimization solutions show that there is a significant difference for minimum contact time at different process conditions.
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film Pore Diffusion modeling for the sorption of metal ions from aqueous effluents onto peat
Water Research, 2001Co-Authors: Buning Chen, Chi Wai Hui, Gordon MckayAbstract:The sorption of three metal ions, namely, copper, nickel and lead onto sphagnum peat moss has been studied using an agitated batch sorber system. The equilibrium isotherms were determined and kinetic runs were performed over a range of concentrations for each metal ion. A film-Pore Diffusion mass transfer model has been developed based on a single effective Diffusion coefficient for each system. Error analysis of the experimental and theoretical data indicated relatively large errors at low initial metal ion concentrations. Therefore the model was modified to introduce a surface coverage concentration dependent effective diffusivity to account for a contribution from surface Diffusion.
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film Pore Diffusion control for the batch sorption of cadmium ions from effluent onto bone char
Journal of Colloid and Interface Science, 2001Co-Authors: Chun Wai Cheung, John F Porter, Chak K Chan, Gordon MckayAbstract:Abstract The sorption equilibrium and kinetics of cadmium ions from aqueous solution onto bone char have been studied. Equilibrium isotherms for the sorption system were correlated by Langmuir and bi-Langmuir equations. The application of the bi-Langmuir equation was developed because the mechanistic analysis in this research indicated that cadmium removal occurs ion exchange and physical adsorption onto different surface sites. The bi-Langmuir equation provides a better fit to the experimental data. In addition, the removal rates of cadmium ions based on the Langmuir models have been investigated. The effective diffusivity was calculated using the effects of initial metal ion concentration and bone char mass. Two mass-transport models based on film-Pore Diffusion control have been applied to analyze the concentration decay curves. The film and Pore Diffusion coefficients using an analytical equation are equal to 1.26×10 −3 cm/s and 5.06×10 −7 cm 2 /s, respectively. The Pore Diffusion coefficient obtained from the numerical method is 4.89×10 −7 cm 2 /s. A sensitivity analysis showed that the film-Pore Diffusion model and constant effective diffusivity could be used to describe the mass-transport mechanism of the sorption system with a high degree of correlation.
Nienhwa Linda Wang - One of the best experts on this subject based on the ideXlab platform.
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a parallel Pore and surface Diffusion model for predicting the adsorption and elution profiles of lispro insulin and two impurities in gradient elution reversed phase chromatography
Journal of Chromatography A, 2010Co-Authors: Peilun Chung, Jennifer Galvez Bugayong, Chim Yong Chin, Nienhwa Linda WangAbstract:Abstract Lispro insulin (LPI), a widely used insulin analog, is produced on tons per year scale. Linear gradient reversed phase chromatography (RPC) is used in the production to separate LPI from two impurities, which differ from LPI by a single amino acid residue. A chromatography model for the ternary separation in this RPC process is unavailable from the literature. In this study, a parallel Pore and surface Diffusion model is developed and verified for LPI and the two impurities. The LPI can be recovered with high yield (≥95%) and high purity (>99.5%). A new method, which requires a small amount of materials and an order of magnitude fewer experiments, has been developed to estimate the solvent-modulated isotherm parameters. A modified reversed phase modulator model is developed to correlate the adsorption isotherms of LPI and impurities. A strategy has been developed for estimating the intrinsic Pore diffusivity and surface diffusivity. Since the adsorption affinities decrease by more than three orders of magnitude as organic fraction (φ) increases from 0.19 to 0.40, the apparent diffusivities based on a Pore Diffusion model or a surface Diffusion model can also vary by several orders of magnitude. For this reason, a Pore Diffusion model or a surface Diffusion model with a constant apparent diffusivity cannot predict closely the chromatograms over the same range of organic fractions, concentrations, and loadings. The parallel Pore and surface Diffusion model with constant diffusivities can predict closely the frontal and elution profiles over a wide range of organic fractions (0.19–0.40), LPI concentrations (0.05–18 g/L), linear velocities (
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a parallel Pore and surface Diffusion model for predicting the adsorption and elution profiles of lispro insulin and two impurities in gradient elution reversed phase chromatography
Journal of Chromatography A, 2010Co-Authors: Peilun Chung, Jennifer Galvez Bugayong, Chim Yong Chin, Nienhwa Linda WangAbstract:Lispro insulin (LPI), a widely used insulin analog, is produced on tons per year scale. Linear gradient reversed phase chromatography (RPC) is used in the production to separate LPI from two impurities, which differ from LPI by a single amino acid residue. A chromatography model for the ternary separation in this RPC process is unavailable from the literature. In this study, a parallel Pore and surface Diffusion model is developed and verified for LPI and the two impurities. The LPI can be recovered with high yield (≥95%) and high purity (>99.5%). A new method, which requires a small amount of materials and an order of magnitude fewer experiments, has been developed to estimate the solvent-modulated isotherm parameters. A modified reversed phase modulator model is developed to correlate the adsorption isotherms of LPI and impurities. A strategy has been developed for estimating the intrinsic Pore diffusivity and surface diffusivity. Since the adsorption affinities decrease by more than three orders of magnitude as organic fraction (φ) increases from 0.19 to 0.40, the apparent diffusivities based on a Pore Diffusion model or a surface Diffusion model can also vary by several orders of magnitude. For this reason, a Pore Diffusion model or a surface Diffusion model with a constant apparent diffusivity cannot predict closely the chromatograms over the same range of organic fractions, concentrations, and loadings. The parallel Pore and surface Diffusion model with constant diffusivities can predict closely the frontal and elution profiles over a wide range of organic fractions (0.19-0.40), LPI concentrations (0.05-18 g/L), linear velocities (<10 cm/min), and loading volume (0.0004-13 CV). For large loading stepwise and linear gradient elution, the peaks of LPI and the impurities are strongly focused by self-sharpening and gradient focusing effects as a result of the steep decrease of adsorption affinity from the loading φ (0.19) to elution φ (≥0.27). When the ratio of Diffusion rate to convection rate is greater than 10, spreading due to Diffusion is largely compensated by the focusing effects. As a result, a Pore Diffusion model with a constant Pore diffusivity can predict closely the elution profiles in stepwise and linear gradient elution. The experimental yield values (≥95%) can be predicted to within ±1% by the model.
Jiayi Zheng - One of the best experts on this subject based on the ideXlab platform.
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adsorption isotherm kinetics simulation and breakthrough analysis of 5 hydroxymethylfurfural adsorption desorption behavior of a novel polar modified post cross linked poly divinylbenzene co ethyleneglycoldimethacrylate resin
Chemosphere, 2020Co-Authors: Jiayi Zheng, Chiliu Cai, Jiangxiong Xiao, Yao Liu, Zhe Chen, Baoying Pan, Xiaoqing LinAbstract:Abstract A polar modified post-cross-linked poly (divinylbenzene-co-ethyleneglycol-dimethacrylate) (PCL-PDE) resin was synthesized by suspension polymerization of ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB), and a post-cross-linked reaction. After characterization, the adsorption behaviors of 5-hydroxymethylfurfural (5-HMF) on PCL-PDE resin were determined in comparison with the starting copolymers PDE resin. The equilibrium adsorption capacity of 5-HMF on PCL-PDE resin was much larger than PDE resin and the increase rate was greater than 52.6%. The equilibrium data of 5-HMF onto PCL-PDE resin were found to be better fitted by the Langmuir isotherm model. The kinetic data shows that the adsorption reached equilibrium in a short time (less than 20 min) can be fitted by the Pore Diffusion model (PDM) at various operating conditions. The effective Pore Diffusion coefficient was dependent upon adsorption temperature, and were 6.706 × 10−10, 8.958 × 10−10, 1.136 × 10−9 and 1.429 × 10−9 m2 s−1 at 288, 298, 308 and 318 K, respectively. Furthermore, the effects of feed flow rate (Qf = 0.6, 1.5, 3.0 and 6.0 mL min−1) and initial 5-HMF concentration (cf = 0.52, 1.02, 2.00 and 4.96 g L−1) on the adsorption were investigated systematically. Besides, a general rate model (GRM) was used to predict adsorption breakthrough curves of 5-HMF. The simulation results are highly consistent with the experimental data, indicating that the GRM can successfully simulate this process. In the desorption process, the desorption capacity reaches 99.6% of adsorbed capacity, suggesting that the PCL-PDE resin exhibited good reusability. Therefore, it could be suggested that the PCL-PDE resin has a potential application in the separation and purification of 5-HMF.
Robert Rex Sever - One of the best experts on this subject based on the ideXlab platform.
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controlled nucleation in freeze drying effects on Pore size in the dried product layer mass transfer resistance and primary drying rate
Journal of Pharmaceutical Sciences, 2011Co-Authors: Alex K Konstantinidis, Steven L. Nail, Wei Y Kuu, Lori Otten, Robert Rex SeverAbstract:A novel and scalable method has been developed to enable control of the ice nucleation step for the freezing process during lyophilization. This method manipulates the chamber pressure of the freeze dryer to simultaneously induce nucleation in all product vials at a desired temperature. The effects of controlled nucleation on the drying rate of various formulations including 5% (w/w) mannitol, 5% (w/w) sucrose, and a mixture of 3% (w/w) mannitol and 2% (w/w) sucrose were studied. For a 5% (w/w) mannitol, uncontrolled ice nucleation occurred randomly at product temperatures between -8.0°C and -15.9°C as the vials were cooled to -40°C. Controlled ice nucleation was achieved at product temperatures between -2.3°C and -3.7°C. The effect of nucleation control on the effective Pore radius (r(e) ) of the cake was determined from the product temperature profiles using a Pore Diffusion model in combination with a nonlinear parameter estimation approach reported earlier. Results show that the value of r(e) for 5% (w/w) mannitol was enlarged from 13 to 27 μm by uniformly inducing nucleation at higher temperatures. Applying the resistance parameters obtained from the Pore Diffusion model for 5% (w/w) mannitol, optimized cycles were theoretically generated and experimentally tested, resulting in a 41% reduction in primary drying time.
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controlled nucleation in freeze drying effects on Pore size in the dried product layer mass transfer resistance and primary drying rate
Journal of Pharmaceutical Sciences, 2011Co-Authors: Alex K Konstantinidis, Steven L. Nail, Lori Otten, Robert Rex SeverAbstract:ABSTRACT A novel and scalable method has been developed to enable control of the ice nucleation step for the freezing process during lyophilization. This method manipulates the chamber pressure of the freeze dryer to simultaneously induce nucleation in all product vials at a desired temperature. The effects of controlled nucleation on the drying rate of various formulations including 5% (w/w) mannitol, 5% (w/w) sucrose, and a mixture of 3% (w/w) mannitol and 2% (w/w) sucrose were studied. For a 5% (w/w) mannitol, uncontrolled ice nucleation occurred randomly at product temperatures between −8.0°C and −15.9°C as the vials were cooled to −40°C. Controlled ice nucleation was achieved at product temperatures between −2.3°C and −3.7°C. The effect of nucleation control on the effective Pore radius ( r e ) of the cake was determined from the product temperature profiles using a Pore Diffusion model in combination with a nonlinear parameter estimation approach reported earlier. Results show that the value of r e for 5% (w/w) mannitol was enlarged from 13 to 27 μm by uniformly inducing nucleation at higher temperatures. Applying the resistance parameters obtained from the Pore Diffusion model for 5% (w/w) mannitol, optimized cycles were theoretically generated and experimentally tested, resulting in a 41% reduction in primary drying time. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:3453–3470, 2011