EFFECT OF VISCOSITY ON MEMBRANE FLUXES IN CROSS-FLOW ULTRAFILTRATION

For practical applications of ultrafiltration (UF), an estimation of m embrane fluxes under various operational conditions is very important. This study analyzed concentration polarization (CP) as a coupled tran sport problem with concentration-dependent solute viscosity. Besides t he effects of variable viscosity, the model includes the effects of so lute osmotic pressure, solute rejection at the membrane surface, and t he axial pressure drop. This provides a fundamental understanding of t he effects of various operating parameters on concentration polarizati on and transmembrane flux. A finite-difference solution of the transpo rt equations is presented to model the concentration polarization in a thin-channel UF system. Simulation results for ultrafiltration of Dex tran T-70 show that concentration-dependent solute viscosity adversely affects the transmembrane flux and needs to be carefully considered i n modeling concentration polarization in membrane filtration.