TY - JOUR

T1 - Modeling of flux decline during crossflow ultrafiltration of colloidal suspensions

AU - Lee, Yonghun

AU - Clark, Mark M.

N1 - Funding Information:
The authors wish to thank the National Science Foundation under Grant No. BCS 90-57387, and U.S. Army Construction Engineering Research Laboratories under Contract No. DACA88-93-D-0010 and DACA88-93-D-0023 for providing financial support.

PY - 1998/10/28

Y1 - 1998/10/28

N2 - Mass transfer during crossflow ultrafiltration is mathematically expressed using the two-dimensional convective-diffusion equation. Numerical simulations showed that mass transfer in crossflow filtration quickly reaches a steady-state for constant boundary conditions. Hence, the unsteady nature of the permeate flux decline must be caused by changes in the hydraulic boundary condition at the membrane surface due to cake formation during filtration. A step-wise pseudo steady-state model was developed to predict the flux decline due to concentration polarization during crossflow ultrafiltration. An iterative algorithm was employed to predict the amount of flux decline for each finite time interval until the true steady-state permeate flux is established. For model verification, crossflow filtration of monodisperse polystyrene latex suspensions ranging from 0.064 to 2.16μm in diameter was studied under constant transmembrane pressure mode. Besides the crossflow filtration tests, dead-end filtration tests were also carried out to independently determine a model parameter, the specific cake resistance. Another model parameter, the effective diffusion coefficient, is defined as the sum of molecular and shear-induced hydrodynamic diffusion coefficients. The step-wise pseudo steady-state model predictions are in good agreement with experimental results of flux decline during crossflow ultrafiltration of colloidal suspensions. Experimental variations in particle size, feed concentration, and crossflow velocity were also effectively modeled. Copyright (C) 1998 Elsevier Science B.V.

AB - Mass transfer during crossflow ultrafiltration is mathematically expressed using the two-dimensional convective-diffusion equation. Numerical simulations showed that mass transfer in crossflow filtration quickly reaches a steady-state for constant boundary conditions. Hence, the unsteady nature of the permeate flux decline must be caused by changes in the hydraulic boundary condition at the membrane surface due to cake formation during filtration. A step-wise pseudo steady-state model was developed to predict the flux decline due to concentration polarization during crossflow ultrafiltration. An iterative algorithm was employed to predict the amount of flux decline for each finite time interval until the true steady-state permeate flux is established. For model verification, crossflow filtration of monodisperse polystyrene latex suspensions ranging from 0.064 to 2.16μm in diameter was studied under constant transmembrane pressure mode. Besides the crossflow filtration tests, dead-end filtration tests were also carried out to independently determine a model parameter, the specific cake resistance. Another model parameter, the effective diffusion coefficient, is defined as the sum of molecular and shear-induced hydrodynamic diffusion coefficients. The step-wise pseudo steady-state model predictions are in good agreement with experimental results of flux decline during crossflow ultrafiltration of colloidal suspensions. Experimental variations in particle size, feed concentration, and crossflow velocity were also effectively modeled. Copyright (C) 1998 Elsevier Science B.V.

KW - Concentration polarization

KW - Diffusion

KW - Flux decline

KW - Specific cake resistance

KW - Ultrafiltration

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U2 - 10.1016/S0376-7388(98)00177-X

DO - 10.1016/S0376-7388(98)00177-X

M3 - Article

AN - SCOPUS:0032576167

SN - 0376-7388

VL - 149

SP - 181

EP - 202

JO - Jornal of Membrane Science

JF - Jornal of Membrane Science

IS - 2

ER -