Inter-Polymer Anionic Reverse Osmosis Membrane Derived from Ethylene-Vinyl Alcohol Copolymer and Poly(styrenesulfonic acid)

Abstract

Inter-polymer anionic reverse osmosis membranes were prepared from ethylene-vinyl alcohol copolymer (EVA) and poly (styrenesulfonic acid) (PSSA) The effects of composition of a casting solution, temperature, and time of heat treatment on the performance of the resulting membranes have been studied. A mixture of 1-propanol and water (71.7/28.3, wt%) was used as a casting solvent. Membranes were prepared by casting a homogeneous polymer solution on a horizontal glass plate and by evaporating the solvent at a proper temperature. EVA homogeneous membrane had very poor performance as a reverse osmosis membrane. The optimum composition of a casting solution was as follows: weight percentage of EVA/PSSA/solvent being 9/6/85. The membrane was formed by casting the solution and heating at 120°C for 45min to give a good performance for reverse osmosis, viz., water flux of 4.5∼7.2l/m2⋅h an d salt rejection of 90∼91% under 80 kg/cm2 with 0.5% NaCl aqueous solution. The water flux and salt rejection closely related to interstitial ionic concentration and water content in a membrane.