Low pressure reverse osmosis performances of sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) thin film composite membranes: effect of coating conditions and molecular weight of polymer

Thin film composite (TFC) membranes with sulfonated poly(2,6-dimethyl-1,4-p henylene oxide) (SPPO) as the top layer coated on ultrafiltration (UF) memb ranes were prepared under different preparation conditions including the po lymer concentration, solvent used in the coating solution, drying temperatu re, and the polymer molecular weight. Membrane performances for nanofiltrat ion that separated electrolytes such as MgSO4 and NaCl from aqueous solutio n were investigated using the composite membranes thus prepared. The concen tration of SPPO both in H+-form and in Na+-form showed different tendencies for MgSO4 separation while it did not affect the separation of NaCl. Membr ane permeation rate increased on increasing the molecular weight of the gly col ethers used as the solvent without sacrificing separation. TFC membrane s prepared from high molecular weight SPPO exhibited better performances as compared to those prepared from lower molecular weight SPPO. (C) 2000 Else vier Science B.V. All rights reserved.