Preparation of polyamide/cellulose acetate thin-film composite forward osmosis membranes and optimization of phase inversion process parameters
Forward osmosis(FO)technology has the advantages of low operating pressure,energy consumption and membrane fouling.It may contribute to solutions to ease the water and energy shortage in the world.However,the lack of stable and high permselective FO membranes has thwarted its wide spread applications.In this paper,starting from adjusting the process parameters of phase inversion,the structure and properties of cellulose acetate(CA)substrates were effectively controlled by changing the kinds of additives and the operation parameters(coating thickness,solvent evaporation time and coagulation bath temperature).Then polyamide(PA)separation layer was formed on the hydrophilic porous CA substrate by interface polymerization(IP)to obtain the thin-film composite FO membrane.The experimental results showed that when the casting solution composed of 10%CA and Porogen A was cast under a 150μm gap and coagulated at 25℃to form porous CA substrate,the stable TFC-FO membranes could be prepared from IP to have the best permselectivity.With 1mol/L NaCl solution as the drug substance(DS)and deionized water(DIW)as the feed solution(FS),the FO water flux reached 10.94L/(m2·h)under a low reverse salt flux value of 0.0500mol/(m2·h).Its NaCl rejection rate was 95.0%and the structure parameter(S)was 1404μm.