The Effect of a Cationic Polyelectrolyte on the Electrokinetic Properties of a Nanofiltration Membrane and Retention of Ions by It

Abstract

Electrokinetic properties of an asymmetric nanofiltration membrane modified with a cationic polyelectrolyte (styrene–dimethylaminopropylmaleimide copolymer) and the selectivity of the membrane with respect to solutions of differently charged electrolytes have been studied. The modification has been carried out by filtering the polyelectrolyte from the side of the selective layer and the opposite side of the membrane. It has been found that the membrane selectivity to sodium sulfate and magnesium chloride solutions increases with polyelectrolyte concentration in the solution used for membrane modification from the side of the selective layer. A decreased selectivity to sodium sulfate and an unchanged selectivity to magnesium chloride have been observed for the membrane modified from the substrate side.