Preparation and properties of a composite charged membrane

Abstract

In order to develop a low pressure desalination membrane with fixed ionic charges, we made use of the normally unwanted crosslinking tendency in preparing the polyelectrolyte poly(styrenesulfonate) by sulfonation of polystyrene. After dipcoating a poly(sulfone) or poly(phenylene oxide) UF membrane with a dilute soluton of this polyelectrolyte in water in the presence of some free sulfuric acid and silversulfate, fixation and cross-linking of the coating polymer took place by a heat treatment.\ud \ud Different membrane properties could be obtained by varying the pore size of the supporting UF membranes, and by variation in the coating polymer (M.W., concentration) and sulfuric acid concentration. We found that fluxes sometimes decline drastically in comparison with the original pure water flux; salt rejection values (at 1.5 g/l NaCl concentration and 0.5 MPa) never are very high (≤60% for monovalent anions). The most important potential application for these membranes lies in their non-fouling properties