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PERVAPORATION SEPARATION OF N-HEPTANE/ORGANOSULFUR MIXTURES WITH PDMS MEMBRANE: EXPERIMENTAL AND modelLING

CANADIAN JOURNAL OF CHEMICAL ENGINEERING 2009年第4期87卷 547-553页

作者： Huang, Junqi Li, Jiding Chen, Jian Zhan, Xia Chen, Cuixian Tsinghua Univ Dept Chem Engn Beijing 10084 Peoples R China

In this paper, polydimethylsiloxane (PDMS) pervaporation membrane was employed to simulate the desulfurization process of gasoline where n-heptane was selected to stand for gasoline. A modified solution-diffusion model is proposed to account for the mass transport of penetrants in the polymer membrane. In the model, the group contribution method (the UNIFAC-ZM model) is applied to calculate the activity of penetrants in the polymer membrane, and the free volume theory with some modifications is employed to describe the diffusion behaviour of the penetrants. The effects of operating temperature and feed concentration on pervaporation properties were investigated to validate the model. It has been shown that the results predicted by the solution-diffusion model are in good agreement with the experimental values.

关键词： pervaporation solution-diffusion model group contribution method

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Steady state modeling for membrane separation of pretreated liming effluent under cross-flow mode

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JOURNAL OF MEMBRANE SCIENCE 2009年第1-2期338卷 175-181页

作者： Das, Chandan De, Sirshendu Indian Inst Technol Dept Chem Engn Kharagpur 721302 W Bengal India Indian Inst Technol Dept Chem Engn Gauhati 781039 Assam India

A steady state model is formulated for a two step membrane separation processes (ultrafiltration followed by nanofiltration) for treatment of the liming effluent collected from a tannery. The extent of polarization on the membrane surface is quantified. The model parameters are determined by fitting of the calculated results of permeate flux and permeate concentration with the corresponding experimental data. solution diffusion and osmotic pressure model are combined for continuous, cross-flow membrane processes. Three flow regimes, namely, laminar, laminar with promoter and turbulent are investigated. The effective osmotic coefficient, solute diffusivity, solute permeability through the membrane have been estimated for liming effluent of a tannery. For both ultrafiltration and nanofiltration, the extent of polarization increases with tramsmembrane pressure and decreases with cross-flow rate. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Cross-flow Liming effluent Ultrafiltration Nanofiltration Concentration polarization solution-diffusion model

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Screening of reverse osmosis membranes for the treatment and reuse of distillery condensates into alcoholic fermentation

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DESALINATION 2008年第1-3期219卷 335-347页

作者： Sagne, Camille Fargues, Claire Lewandowski, Richard Lameloise, Marie-Laure Decloux, Martine AgroParis Tech UMR GENIAL F-91744 Massy France

Industries including a fermentation step use large volumes of water to dilute their musts. In beet alcohol distilleries, this water is recovered as condensates during stillage concentration. Because of their high organic content, these condensates cannot be discharged without a treatment. The elimination of inhibitory solutes that they contain would enable their recycling into alcoholic fermentation. Reverse osmosis is an interesting process within this framework but membrane behavior with respect to small organic solutes is little known. A pre-selection step was necessary to choose among eight appropriate membranes (ESPA2, LFC3 and CPA2 from Hydranautics, BW30 and BW30LE from Filmtec, SG, SE and CE from Osmonics) the best one for this application. Their efficiency was estimated according to permeate fluxes, fermentation ability and solute concentration measurements, obtained at two pH and volume reduction factors. Permeate fluxes were high (between 35 and 120 L.m(-2).h(-1)). The target solutes were well rejected (between 82.2 and 99.2%) and permeate inhibitory effect was weak (between 0 and 5.2%). According to these three criteria, ESPA2 membrane appeared to be the most efficient, followed by CPA2. Results were linked to membrane manufacturers' data and showed that the latter were not appropriate to differentiate membranes for this application. Permeabilities were calculated according to the solution-diffusion model and showed that transfer mechanism is different from one molecule to another.

关键词： wastewater treatment RO fermentation condensate solution-diffusion model organic solutes

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Effect of selective layer thickness on pervaporation of composite poly(vinyl alcohol)-poly(sulfone) membranes

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JOURNAL OF MEMBRANE SCIENCE 2008年第1-2期318卷 387-396页

作者： Hyder, M. N. Huang, R. Y. M. Chen, P. Univ Waterloo Dept Chem Engn Waterloo ON N2L 3G1 Canada

Effects of the selective layer thickness of flat composite membranes were studied on pervaporation. Selective layers of different thicknesses were prepared from poly(vinyl alcohol), and the porous support layer was prepared from poly(sulfone). The microstructure, surface roughness and hydrophobicity of the selective PVA layers were determined from SEM, AFM and contact angle measurements, respectively. For each composite PVA-PSf membrane, dehydration of ethanol-water mixtures was conducted over a range of ethanol concentrations (10-85wt%) in the feed solution. Results of the total flux and selectivity were obtained and statistically analyzed as a function of selective layer thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux is significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed in the selectivity has been related to changes in surface properties of the crosslinked membrane, especially when the selective layer thickness is small. (c) 2008 Elsevier B.V. All rights reserved.

关键词： composite membrane selective layer thickness atomic force microscopy surface roughness swelling per unit thickness solution-diffusion model flux and selectivity

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Pervaporation performance analysis and prediction - using a hybrid solution-diffusion and pore-flow model

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JOURNAL OF THE CHINESE INSTITUTE OF CHEMICAL ENGINEERS 2007年第1期38卷 43-51页

作者： Cheng-Liang Chang Hsuan Chang Yuan-Cheng Chang Tamkang Univ Dept Chem & Mat Engn Tamsui 25137 Taiwan

A hybrid mathematic model for pervaporation is proposed which incorporates the concepts of solution-diffusion model and pore model. The model allows performance prediction as well as the establishment of the internal concentration and pressure profiles within the membrane. The model parameters specific to the particular membrane and mixture system are determined using liquid sorption and pervaporation experimental data. The model is experimentally examined using ethanol-water mixtures and poly(dimethyl siloxane)-poly(vinyldiene fluoride) (PDMS-PVDF) composite membranes. The characteristics of flux and separation factor predicted using the model are in fair agreement with the experimental data under various feed concentrations and downstream pressures for different membrane arrangements, including single-layer, reverse single-layer and double-layer PDMS-PVDF composite membranes. Internal profiles of pressure, concentration and component mole fraction can be established using the model. Concentration polarization phenomena for ethanol and water are located at membrane interfaces and vapor-liquid interfaces, respectively. Performances of several different membrane designs are compared using the model. (c) 2007 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： pervaporation solution-diffusion model pore model concentration polarization ethanol-water solution

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Effect of back diffusion and back permeation of air on membrane characterization in constant pressure system

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JOURNAL OF MEMBRANE SCIENCE 2008年第1-2期324卷 162-172页

作者： Lashkari, S. Tran, A. Kruczek, B. Univ Ottawa Dept Chem & Biol Engn Ottawa ON K1N 6N5 Canada

Constant pressure (CP) testing systems are often used in characterization of gas separation membranes. Unlike constant volume (CV) systems, the membrane tested a CP system is exposed to atmosphere via a flow metering device. Consequently, as long as the permeating gas has a composition different from that of the atmosphere, there is a driving force for diffusion of atmospheric gases towards the membrane. If as a consequence this there is a nonzero partial pressure of the back diffusing gases at the permeate side of the membrane they may permeate to the feed side of the membrane (back permeation). This paper presents a mathematical model that allows estimation of an error arising from back diffusion and back permeation in CP systems. The model is derived from the first principles assuming that there are no interactions between the forward and back permeating gases with each other and with the membrane. The theoretical predictions are then compared with experimental results obtained in a specially designed, fully-automated CP system. using poly-2,6-dimethyl-1,4-phenylene oxide (PPO) films in single gas permeation tests involving nitrogen and oxygen. The experimental results confirm theoretically predicted trends resulting from the phenomena of back diffusion and back permeation. However, the influence of these phenomena on the experimentally determined permeability coefficients is greater than that predicted by the model. (C) 2008 Elsevier B.V. All rights reserved.

关键词： membrane characterization back diffusion back permeation constant pressure system solution-diffusion model

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Prediction of Nanofiltration Performance by Using Membrane Transport models for the Separation of Nickel Salts from Aqueous solutions

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CHEMICAL PRODUCT AND PROCESS modelING 2008年第1期3卷

作者： Boricha, Alka G. Murthy, Z. V. P. SV Natl Inst Technol Dept Chem Engn Surat 395007 Gujarat India

Nanofiltration (NF) is considered to be an intermediate process between reverse osmosis (RO) and ultrafiltration (UF). In the present work, separation data obtained for nickel sulfate-water and nickel chloride-water systems, using an N, O-carboxymethyl chitosan (NOCC)-polyether sulfone (PES) composite NF membrane, are analyzed with the help of two nonlinear membrane transport models, viz., combined film theory-solution-diffusion (CFSD) model and combined film theory-Spiegler-Kedem (CFSK) model. The membrane transport parameters and mass transfer coefficient (k) are estimated, simultaneously, from both the models using the Levenberg-Marquardt method. The k values estimated from two models show a variation that may be attributed to the presence of reflection coefficient in the Spiegler-Kedem model. Though both the models predict the membrane performance reasonably, the values of CFSK model are more accurate in the present case. Hence, it can be suggested that CFSK model may be the better method for estimating the membrane transport parameters and k. Various parameters estimated from the above models are used to find the enrichment factors, concentration polarization modulus and Peclet numbers for both the systems.

关键词： nanofiltration solution-diffusion model Spiegler-Kedem nickel separation

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Separation of furfural from aqueous solution by pervaporation using HTPB-bcased hydrophobic polyurethaneurea membranes

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DESALINATION 2007年第1-3期208卷 146-158页

作者： Ghosh, Ujjal K. Pradhan, Narayan C. Adhikari, Basudam Indian Inst Technol Dept Chem Engn Kharagpur 721302 W Bengal India Indian Inst Technol Ctr Mat Sci Kharagpur 721302 W Bengal India

Hydroxyterminated polybutadiene (HTPB) was reacted with 2,4-toluylene diisocyanate (TDI) in THF medium followed by the addition of a diamine chain extender, 4,4'-diaminodiphenyl sulfone (DADPS) to prepare polyurethaneurea (PUU). The prepared viscous polyurethaneurea solution was cast over a glass Petri dish to obtain polymer membrane. Pervaporative separation of furfural/water mixtures was performed by using prepared flat sheet hydrophobic polyurethaneurea membranes. The effect of feed composition on the membrane performance was described by the permeate flux of furfural and separation factor. The synthesized polyurethaneurea membrane was found to permeate furfural selectively with high separation factor for the organic component.

关键词： pervaporation aqueous furfural polyurethaneurea separation factor activation energy solution-diffusion model

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Modified solution-diffusion model analysis of the flue gas desulfurization effluents in a polyamide membrane

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POLYMER TESTING 2003年第1期22卷 109-113页

作者： Yen, HY Yang, MH Kao Yuan Inst Technol Dept Chem Engn Kaohsiung 82101 Taiwan

The characteristics of the hydraulic permeation of flue gas desulfurization (FGD) effluents in a polyamide membrane were studied under various operating pressures and temperatures. It was found that the water flux and solute rejection increased with an increase in the operating pressure. According to these results, a modified solution-diffusion model developed by Yang & Chu was used to describe the case of the FGD effluent transport through a polyamide membrane under various operating pressures and temperatures, which were discussed and evaluated as the respective transport parameters. It was found that the diffusivity for water increased with increasing temperature and the activation energy of diffusivity for water was 11.4 kJ/mole. Moreover, the permeability for solute increased with increasing temperature and the activation energy of permeability of salt was 22.1 kJ/mole. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： solution-diffusion model flue gas desulfurization polyamide membrane

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Separation of water and o-chlorophenol by pervaporation using HTPB-based polyurethaneurea membranes and application of modified Maxwell-Stefan equation

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JOURNAL OF MEMBRANE SCIENCE 2006年第1-2期272卷 93-102页

作者： Ghosh, UK Pradhan, NC Adhikari, B Indian Inst Technol Dept Chem Engn Kharagpur 721302 W Bengal India Indian Inst Technol Ctr Mat Sci Kharagpur 721302 W Bengal India

Hydroxyterminated polybutadiene (HTPB) was reacted with 2,4-toluylene diisocyanate (TDI) followed by the addition of 4,4'diaminodiphenyl sulfone (DADPS) (diamine chain extender) to prepare polyurethaneurea (PUUSD). The prepared polyurethaneurea was cast over glass petridish to obtain polymer membrane. The pervaporation (PV) performance of the synthesized membrane was studied with aqueous o-chlorophenol solution as feed. The polyurethaneurea membranes were found to be selective towards aromatic component with separation factors > 250. The total flux as well as those of the individual components was measured. The effects of various parameters, such as feed composition and temperature, membrane thickness on permeate flux and separation factor were determined. The activation energy for o-chlorophenol permeation, calculated from Arrhenius plot, indicated that an increase in hard segment content imposed a restriction to the transport of organic component. The dependencies of the pervaporation fluxes and the concentration of organic component in permeate on its concentration in the feed were established with the calculation based on modified Maxwell-Stefan equation. A very close agreement between experimental and theoretical fluxes was observed. (c) 2005 Elsevier B.V. All rights reserved.

关键词： pervaporation hydroxyterminated polybutadiene (HTPB) polyurethaneurea o-chlorophenol separation factor solution-diffusion model Maxwell-Stefan equation

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