Preparation and testing of novel hydrophilic embedded composite membranes for water purification systems

In this study, polysulfone composite membranes were prepared by using poly(2,2'-(m-phenylene)-,5'-bibenzimidazole) (PBI), poly(2,5-benzimidazole) (ABPBI), poly(2,2'- (m-phenol)5,5'-bibenzimidazole) (PBIOH), different PBI terpolymers, ZnO nanoparticles and montmorillonite modified with HDTMA (OMMT) as additive. The structure, morphology, performance and fouling resistance of membranes containing additives in various ratios were investigated by using IR, TG, DSC, SEM techniques and cross-flow ultrafiltration tests. It was observed that the composite membranes had higher hydrophilicty, flux, rejection performances and higher fouling resistant than pristine PSf membrane. It was determined that all the composite membranes except for containing large amounts of inorganic additives had higher porosity and equilibrium water content about 40% and 12% respectively. It was observed that the contact angle of pristine PSf membrane which was 69.6°, decreased to 51, 25, 38, 53, 28 and 55° after addition of PBI, PBIOH, ABPBI, terpolymer, OMMT and ZnO, respectively. The pure water fluxes of membranes became higher about 1.6, 2.3 and 2.0 times with PBI, PBIOH and ABPBI additives, respectively. The pure water fluxes of inorganic embedded membranes increased up to the additive amount of 0.5% and then decreased at higher additive ratios. The BSA rejection performances were determined ~36% for pristine PSf membran and 69, 78, 59, 83, 62 and 77% for the PBI, PBIOH, ABPBI, terpolymer, OMMT and ZnO embedded membranes, respectively. Also, pH dependence of BSA rejection was determined. The flux recovery ratio of 1% PBI embedded PSf composite membrane was 94% and it was higher about 20% than pristine PSf membran's result.