A MAXWELL-STEFAN APPROACH TO MODELING THE CROSS-FLOW ULTRAFILTRATION OF PROTEIN SOLUTIONS IN TUBULAR MEMBRANES

A non-parameterised model is developed to predict the crossflow membra ne ultrafiltration permeate flux for protein solutions. A relatively s imple hydrodynamic model is used to predict the rate of growth of the concentration polarisation boundary layer along the length of a tubula r membrane. Protein transport within the boundary layer is evaluated u sing the Maxwell-Stefan transport equations, accounting for electrosta tic interactions created by filtering charged protein molecules. Numer ic simulations were performed with and without considering viscous int eractions in the concentration polarisation boundary layer. In the mai n, the model appears to qualitatively describe the ultrafiltration pro cess very well when tested for a range of different operating paramete rs and solution conditions. However, at high TMPs viscous interactions were exaggerated and the model underpredicted permeate flux. Under su ch conditions, use of the model without accounting for viscous interac tions seemed more appropriate. The model predictions are tested agains t sample experimental data for the protein BSA and the results were hi ghly encouraging. (C) 1998 Elsevier Science Ltd. All rights reserved.