Modeling of Nanofiltration for ‎Concentrated Electrolyte Solutions using ‎Linearized Transport Pore Model

In this study, linearized transport pore model (LTPM) is applied for modeling nanofiltration (NF) membrane separation process. This modeling approach is based on the modified extended Nernst-Planck equation enhanced by Debye-Huckel theory to take into account the variations of activity coefficient especially at high salt concentrations. Rejection of single-salt (NaCl) electrolyte is investigated to take into account the effect of feed concentration, membrane charge density and pore size on rejection. The results show that the reduction of feed concentration and membrane pore size lead to increase the rejection of electrolyte in NF separation process. Furthermore, increasing the membrane charge density causes the rejection of co-ions to be increased leading to an enhanced total rejection. LTPM is compared to unmodified linearized model which approves the higher precision of the modified model especially at higher concentrations.