Synthesis and Characterization of a Multilayer Membrane with Surface Layers for Water Desalination

Abstract

Multilayer dynamic membranes with a surface layer of polystyrene for the membrane desalination of water have been synthesized in this study. The dynamic layer is formed from polystyrene particles with a particle size of 55–92 nm that are suspended in a filtered aqueous solution of acetone with a pH of 5. The stability of the dynamic layer is provided by a heat treatment of the membrane at a temperature of 50°C for 10 min. The treatment leads to the compaction of the dynamic layer of the membrane. With an increase in the number of dynamic layers, the membrane flux decreases. After the deposition of each subsequent layer, the membrane flux decreases twofold. Thus, the flux of a four-layer nylon–polystyrene (nylon–PS) membrane with respect to distilled water is 142 dm3/(m2 h). The rejection ability of the membranes with respect to Cl–, NO3–, $${\text{SO}}_{{\text{4}}}^{{{\text{2}} - }},$$$${\text{NH}}_{{\text{4}}}^{ + },$$ K+, Na+, Ca2+, and Mg2+ ions from a model solution with a total salinity of 433 mg/dm3 is determined. The rejection ability with respect to singly charged and doubly charged ions is 58 and more than 80%, respectively, at a high flux of 118 dm3/(m2 h).