Preparation And Properties Of Poly (Ether Sulfone) Antifouling Ultrafiltration Membrane With Ionic Side Chains

Our country is one of the most indigent countries of the world’s per capita water resources, with the improper development and pollution, worsening water shortage will be. Membrance sparation technology, especially ultrafiltration membrane technique, which has many advantages such as low energy consumption, non-pollution, high efficiency and so on, is one of the most effective way to increase wastewater reuse rate,. However, in the ultrafiltration(UF) process, the membrane will be fouled inevitably. So we must improve the antifouling property of UF membrane. PAES is one ideal membrane material for its desirable properties including thermostability, chemical stability, but the high hydrophobic of PAES membrane surface severely limits its application in separation. In this dissertation, in order to improve the membrane resistance toward fouling, two different modification strategies had been used.First, we synthesized a series of sulfonated polyphenylsulfone(SPPSU) random copolymers with more flexible sulfoalkylated pendants from sulfonated monomer via direct copolymerization method. The chemical structures of the SPPSU copolymers were confirmed by using(FTIR) and 1HNMR, these SPPSU copolymers showed high thermal property by DSC and TGA. The antifouling SPPSU UF membranes were prepared via the conventional immersion precipitation phase inversion method. The morphologies of the SPPSU membranes were investigated by scanning electron microscopy(SEM), the surface hydrophilicity of the SPPSU membranes were studied by water contact angle, the results indicated that the sulfonation of membrane material is really an effective way to enhance the hydrophilicity. The BSA adsorption expetiment showed that sulphonic groups could prevent the adsorption of BSA effectively. The pure water flux and protein solution permeation through the prepared membranes were increased with the increase of the degree of sulfonation, but when the degree of sulfonation was reaches a certain value, the pure water flux would reduce,instead. The cycle untrafiltration experiments for protein solutionrevealed that nonspecific protein adsorption, especially irreversible protein adsorption, for the SPPSU membranes was significantly reduced, giving a good antifouling performance. However, the excess of sulfonation degree lead to the membrane poor mechanical performance.To further increase the antifouling performance of UF membrane, we synthesized polyphenylsulfone with flexible zwitterionic pendants(PPSU-PyPS), by using bisphenol monomer with group of pyridine in direct copolymerization method. The chemical structures of the copolymers were confirmed by using FTIR and 1HNMR, the PPSU-PyPS copolymers showed better thermal property than SPPSU copolymers. We prepared a series of PPSU/PPSU-PyPS blend UF membranes via conventional immersion precipitation phase inversion methods as same. The morphologies of the PPSU/PPSU-PyPS blend membranes were investigated by scanning electron microscopy, the surface hydrophilicity of PPSU/PPSU-PyPS blend membranes were studied by water contact angle and the results indicated that zwitterionic group would help to increase membranes hydrophilicity. The cycle untrafiltration experiments for protein solution revealed that nonspecific protein adsoption, especially irreversible protein adsorption, for the zwitterionic membrane was significantly reduced, suggesting superior antifouling performance. The PPSU/PPSU-PyPS blend membranes showed better antifouling performance than SPPSU UF membrane.