Modeling the permeate flux and rejection of nanofiltration membrane separation with high concentration uncharged aqueous solutions

In this paper, the influence of feed concentration on the performance of nanofiltration membrane separation under high concentration (0.1-0.98 mol/L) of aqueous glucose is investigated using a commercial spiral-wound nanofiltration membrane. The results of the experiments show that the permeate volume flux and observed rejection at certain operating pressures are influenced seriously by concentration. In this work, the influence of concentration is studied generally based on the solution-diffusion model, from which the concentration polarization boundary resistance R-cp and mass transfer coefficient k as functions of concentrations are obtained for high concentrations. Using these relationships, the observed rejection R-o can be predicted in the case of high concentration. The good agreements between the predicted and experimental values indicate that the models proposed and modified in this work could be used to describe the behavior of nanofiltration membrane separation in a wider range of uncharged aqueous solution concentration. (C) 2012 Elsevier By. All rights reserved.