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modeling and transport parameters during nanofiltration of degreasing effluent from a tannery

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING 2011年第1期6卷 101-109页

作者： Prabhavathy, C. De, S. Indian Inst Technol Dept Chem Engn Kharagpur 721302 W Bengal India

Degreasing effluent from a tannery is treated using a single-step membrane separation (nanofiltration) process in continuous cross-flow mode. The flow regimes encompass the laminar and turbulent zones, including laminar flows with turbulent promoters. Experimental results are reported in the range of transmembrane pressure drop from 828 to 1242 kPa for all three flow regimes. More than 50% flux enhancement is observed by using turbulent promoters compared to purely laminar flow. The performance criteria of the filtration are evaluated in terms of chemical oxygen demand (COD), total dissolved solids (TDS), total solids (TS), pH and conductivity of the permeate. The proposed scheme successfully reduces COD to well below the permissible limits (250 mg/l). A combination of osmotic pressure and solution-diffusion model is used for nanofiltration. Three relevant transport coefficients, namely, the effective osmotic coefficient, solute diffusivity and solute permeability through the membrane are estimated by minimising the sum of errors between the experimental and calculated permeate flux and permeate concentrations. (C) 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

关键词： degreasing effluent cross-flow nanofiltration solution-diffusion model steady-state permeate flux

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modeling of the kinetics of pervaporative recovery of ethanol from fermented broth with the use of the solution-diffusion theory

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DESALINATION AND WATER TREATMENT 2010年第1-3期14卷 185-191页

作者： Staniszewski, Marek Kujawski, Wojciech Univ Warmia & Mazury Olsztyn Fac Food Sci PL-10726 Olsztyn Poland Nicholas Copernicus Univ Fac Chem Membrane Separat Proc Grp PL-87100 Torun Poland

The aim of this study was a mathematical description of the kinetics of ethanol separation from fermentation broth of Saccharomyces cerevisiae yeast by the vacuum pervaporation technique. model equations were developed on basis of the solution-diffusion theory. The finite differences method has been used to calculate the concentration profiles of permeants within the membrane. The optimal number of grid points and their distances were found by numerical tests. The formulated model describes the transport of feed components under the non-stationary conditions. model equations were solved with the use of the backward differentiation method. model parameters were estimated by fitting of experimental data with the use of the Nelder-Mead method. Calculations were performed for separation experiments with broths containing 3-6 wt% of ethanol. Very good agreement with the experimental data was obtained.

关键词： solution-diffusion model Pervaporation Kinetics of separation Ethanol Broth

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Steady state modeling of concentration polarization including adsorption during nanofiltration of dye solution

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SEPARATION AND PURIFICATION TECHNOLOGY 2010年第1期71卷 128-135页

作者： Banerjee, Phalguni De, Sirshendu Indian Inst Technol Dept Chem Engn Kharagpur 721302 W Bengal India

Steady state modeling of nanofiltration of a dye (eosin as model dye) solution was carried out. The model was based on simultaneous solution of solution-diffusion model, film theory and osmotic pressure model. The osmotic pressure model was modified by incorporating adsorption of dyes onto the membrane surface. The model parameters were estimated by comparing the calculated and experimental data of permeate flux and permeate concentration. It was observed that although membrane hydraulic resistance was the dominant one, adsorption resistance becomes more significant with increase in feed dye concentration and transmembrane pressure drop and decrease in crossflow velocity. For example, for eosin feed concentration of 0.2 kg/m(3) and crossflow velocity of 0.46 m/s and transmembrane pressure of 828 kPa, the resistance offered by adsorbed solutes was found to be as high as 21% of the total resistance. The combined model successfully simulates the system performance in terms of permeate flux and permeate concentration. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Nanofiltration solution-diffusion model Adsorption Permeate flux Dye retention

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Mass transport and membrane separations: Universal description in terms of physicochemical potential and Einstein's mobility

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CHEMICAL ENGINEERING SCIENCE 2010年第4期65卷 1474-1489页

作者： Kocherginsky, N. Biomime Urbana IL 61801 USA

General yet simple description of chemical transport processes in non-isolated system is suggested. It is based on extended Teorell equation and just two fundamental parameters: physicochemical potential and Einstein's mobility. Using mobility it is possible to compare the rates of all major linear transport phenomena, including pressure-driven migration and also nonideal and multicomponent diffusion. Relationship with the Stefan-Maxwell approach and Onsager's linear thermodynamics is demonstrated and physical interpretation of both diagonal and off-diagonal phenomenological coefficients is suggested. Imposing boundary conditions for transport equations allows description of transport in homogeneous membranes caused by several concurrent driving factors, such as concentration, pressure, and voltage. Differences of barodiffusion, membrane filtration, and reverse osmosis are considered. For a porous membrane an expression for the pressure-driven volumetric flux through the pores as a function of mobility and pore size is derived. It is explained why hydraulic flow prevails in submicron pores and why diffusion is the dominant mechanism in reverse osmosis if the pressure difference is not too high. The theory naturally leads to the solution-diffusion model equations but does not need usual assumptions of constant pressure across the membrane and the pressure jump only at one surface. Internal pressure and mechanical stress gradients within a membrane exist and can be useful in a description of rheology of aging polymer membranes. A new equation for concurrent diffusion and hydraulic transport is derived and two possible molecular mechanisms leading to the Kedem-Katchalsky equations for reverse osmosis membranes are suggested. Finally, electrokinetic processes are described and their similarity to concentration- and pressure-driven transport is discussed. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Membranes Energy Entropy Separations Transport processes Linear thermodynamics Reverse osmosis Barodiffusion solution-diffusion model

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Mass transport study of PVA membranes for the pervaporation separation of water/ethanol mixtures

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DESALINATION 2010年第1-3期256卷 148-153页

作者： Chen, Jian Huang, Junqi Li, Jiding Zhan, Xia Chen, Cuixian Tsinghua Univ Dept Chem Engn Beijing 100084 Peoples R China

In this paper, the flux and separation factor for water/ethanol mixtures in PVA membrane system are detected and 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 introduced to calculate the activity of penetrants in the polymer membrane, and a modified Fujita temperature-dependence diffusion coefficient equation is developed to describe the diffusion behavior of the penetrants. The aim of this work is to establish a predictive solution-diffusion model. As an exemplary application of the model, the permeation fluxes and separation factors of water/ethanol mixtures in PVA membrane system have been predicted and showed to be in good agreement with experimental values. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

关键词： solution-diffusion model Group contribution method Pervaporation Membrane

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Performance of PDMS membranes in pervaporation: Effect of silicalite fillers and comparison with SBS membranes

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2010年第1期346卷 254-264页

作者： Dobrak, A. Figoli, A. Chovau, S. Galiano, F. Simone, S. Vankelecom, I. F. J. Drioli, E. Van der Bruggen, B. Univ Calabria Res Inst Membrane Technol ITM CNR I-87030 Arcavacata Di Rende Italy Katholieke Univ Leuven Dept Chem Engn Lab Appl Phys Chem & Environm Technol B-3001 Louvain Belgium Katholieke Univ Leuven Dept Microbial & Mol Syst Ctr Surface Chem & Catalysis B-3001 Louvain Belgium

Laboratory-made silicalite filled PDMS membranes were tested by means of concentration and temperature influence on the membrane performance in removal of ethanol from ethanol/water mixtures This allowed studying the applicability of solution-diffusion model in the transport mechanism description Experiments were performed by varying the ethanol concentration in the feed and temperature Two types of fillers were incorporated into the PDMS network commercial zeolite silicalite (CBV 3002) and laboratory-made colloidal silicalite-1 Obtained results were then compared with data gathered for unfilled PDMS membranes to examine the effect of fillers incorporation Moreover, the comparison with novel block co-polymer based porous and dense SBS membranes was done. It was found that the solution-diffusion model was a good representation of ethanol transport through both filled and unfilled PDMS membranes, whereas the water flux did not obey this model due to the swelling effects Incorporation of the fillers increased membrane stability and improved the selectivity Performance of the SBS membranes characterized by a dense structure was found to be similar to the performance of filled PDMS membranes. (C) 2010 Elsevier Inc. All rights reserved.

关键词： PDMS membranes Pervaporation solution-diffusion model Temperature effect Membrane performance

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Analysis of Permeability of Organic Solvents through a Composite Dense Nonporous Membrane

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JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2010年第3期43卷 261-268页

作者： Miyagi, Atsushi Murata, Moriyasu Nabetani, Hiroshi Nakajima, Mitsutoshi Subramanian, Rangaswamy Chiba Ind Technol Res Inst Wakaba Ku Chiba 2640017 Japan Murata Technol & Innovat Consulting Mihama Ku Chiba 2610012 Japan Natl Agr & Food Res Org Natl Food Res Inst Tsukuba Ibaraki 3058642 Japan Univ Tsukuba Grad Sch Life & Environm Sci Tsukuba Ibaraki 3058572 Japan CSIR Cent Food Technol Res Inst Dept Food Engn Mysore 570020 Karnataka India

The permeability of various organic solvents through a composite dense nonporous membrane comprising a silicon polymer as the active layer was studied to elucidate the transport mechanism under steady-state conditions. The permeability was calculated from the difference in the parameters of the solvent and the membrane polymer, vertical bar delta(1) - delta(2)vertical bar, and the molecular weight (size) of the solvent, M(2);vertical bar delta(1)-delta(2)vertical bar and M(2) would correspond to the solubility and diffusivity, respectively. Generally, the permeability of the different groups of common solvents classified on the bases of their molecular sizes tended to increase with a decrease in vertical bar delta(1) - delta(2)vertical bar. However, the M(2) values of the alkane solvents were inversely proportional to their permeabilities. For a more detailed analysis of the transport mechanism, the regular solution model was used. The permeate flux of the solvent, ln (J(2)), showed a linear dependence on the mole fraction of the solvent in the membrane phase, ln (X(2)), and the square of the volume fraction of the solvent in the membrane polymer phase (degree of swelling), Phi(2)(2). In the case of the common solvents, ln (J(2)) showed a linear dependence on the product of the molar volume of the solvent (V(2)) and the square of the solubility parameter difference (delta(1) - delta(2))(2) at constant pressure and temperature. In the case of the alkane solvents, a good correlation was observed between ln (J(2)) and V(2), as the (delta(1)-delta(2))(2) values were numerically around unity. These results agreed with the conclusions drawn from studies performed using the solution-diffusion model. Thus, this new approach is expected to help in the accurate elucidates of the mechanism of transport of a non aqueous liquid through a composite dense nonporous membrane.

关键词： Composite Dense Nonporous Membrane solution-diffusion model Solvent Permeability Regular solution model

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Recovery of copper from process waters by nanofiltration and reverse osmosis

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DESALINATION 2009年第1-3期240卷 132-142页

作者： Csefalvay, Edit Pauer, Viktor Mizsey, Peter Budapest Univ Technol & Econ Dept Chem & Environm Proc Engn H-1111 Budapest Hungary

Copper rejections of a nanofiltration (NF) and a reverse osmosis (RO) membrane are investigated with copper-sulfate and copper-nitrate solutions as test wastewaters. The copper content of the solutions represents the typical copper ion concentration of process waters from a textile coating plant, i.e. 2 kg/m(3). Experiments are performed with the test solutions on a bench-scale cross-flow membrane filtration apparatus with acid resistant flat sheet membranes. The active membrane area is 28 cm(2). Isotherm experiments at 25 degrees C are carried out. The applied conditions (e.g. pressure or pH) are in the applicable range of parameters. Permeate flux, conductivity, pH, and copper concentration of the permeate are measured to determine the membrane characteristic and rejection. The transport through the membrane is modeled in the function of time with the solution-diffusion model and in the function of yield with the modified osmotic pressure model. modeled data is then compared to the experimental data. This comparison shows a good agreement between the measured and the modeled fluxes. Finally, the effect of anion composition on permeate flux is also studied using copper-sulfate and -nitrate at a constant copper content of 2 kg/m(3). However, no influence of the anions on the permeate flux and copper rejection can be observed.

关键词： Nanofiltration Reverse osmosis Process water Copper solution-diffusion model Modified osmotic pressure model

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Pervaporation separation of n-heptane/thiophene mixtures by polyethylene glycol membranes: modeling and experimental

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2009年第1期339卷 152-159页

作者： Lin, Ligang Zhang, Yuzhong Kong, Ying Tianjin Polytech Univ Minist Educ Key Lab Hollow Fiber Membrane Mat & Membrane Proc Tianjin 300160 Peoples R China China Univ Petr E China State Key Lab Heavy Oil Proc Dongying 257061 Peoples R China

Gasoline desulfurization by membrane processes is a newly emerged technology, which has provided an efficient new approach for sulfur removal and gained increasing attention of the membrane and petrochemical field. A deep understanding of the solution/diffusion of gasoline molecules on/in the membrane can provide helpful information in improving or optimizing membrane performance. In this study, a desulfurization mechanism of polyethylene glycol (PEG) membranes has been investigated by the study of sorption and diffusion behavior of typical sulfur and hydrocarbon species through PEG membranes. A solution-diffusion model based on UNIFAC and free volume theory has been established. Pervaporation (PV) and sorption experiments were conducted to compare with the model calculation results and to analyze the mass transport behavior. The dynamic sorption curves for pure components and the sorption experiments for binary mixtures showed that thiophene, which had a higher solubility coefficient than n-heptane, was the preferential sorption component, which is key in the separation of thiophene/hydrocarbon mixtures. In all cases, the model calculation results fit well the experimental data. The UNIFAC model was a sound way to predict the solubility of solvents in membranes. The established model can predict the removal of thiophene species from hydrocarbon compounds by PEG membranes effectively. (C) 2009 Elsevier Inc. All rights reserved.

关键词： Pervaporation Sorption Gasoline desulfurization solution-diffusion model

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modeling permeation of volatile organic molecules through reverse osmosis spiral-wound membranes

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JOURNAL OF MEMBRANE SCIENCE 2009年第1-2期330卷 40-50页

作者： Sagne, Camille Fargues, Claire Broyart, Bertrand Lameloise, Marie-Laure Decloux, Martine AgroParisTech UMR GenIAl 1145 F-91300 Massy France

Reverse osmosis is an interesting process to eliminate organic solutes from distillery condensates before recycling them into the fermentation step. However, organic solutes transport phenomena through reverse osmosis membranes are specific. Rejection and sorption of five compounds were studied on a brackish water membrane. Acetic acid and 2,3-butanediol were not sorbed on the membrane while furfural and 2-phenylethanol presented strong sorption following the Langmuir pattern. These sorption effects coupled with solute molecular weight (MW) led to low rejections of acetic acid and furfural (30-60%) and high rejections of 2,3-butanediol and 2-phenylethanol (80-98%). With inter-mediate sorption and MW. butyric acid showed rejections between 70 and 80%. A modified solution-diffusion model was developed to take into account the sorption pattern and predict the concentration profile along the membrane on the retentate and permeate sides. Equilibrium properties were determined experimentally while transport properties were identified with data obtained from a synthetic condensate. This model was validated for various operating conditions with the synthetic and the industrial condensates. It was then used to simulate the influence of the recovery rate on the retentate and permeate concentrations. It showed the behavior differences between solutes with a linear sorption and solutes with a saturating sorption. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Reverse osmosis Organic solute solution-diffusion model Sorption Distillery condensate

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