Hyperfiltration in porous fixed charge membranes

The hyperfiltration properties of fixed charge membranes containing pores of various widths have been examined under conditions where flows are large and restricted to the pores. The profiles for the ionic concentrations, electrostatic potential and solution velocity across the pore widths have been determined. A generalised expression for the salt rejection coefficient has been derived. It is found that the relation between salt rejection and the salt distribution coefficient simplifies to be of the same form as that which applies for the fixed charge membrane described by Teorell, Meyer and Sievers. The absolute values of the rejection coefficient are smaller however, for porous membranes, since a diminished salt exclusion obtains.