The Investigation Of The Surface Modification And Performance Of Polvamide Membranes By Zwitterionic Materials

Aromatic polyamide thin-film composite (TFC) membranes are now widely used in many desalination and water purification applications due to their excellent performance. Fouling is the major problem faced in membrane application. Membrane fouling could reduce the flux and membrane-life, increase the running cost. Today, researchers mainly focuses on improving the anti-dirty ability through surface modification on PA TFC membranes. Zwitterionic materials show excellent resistance to protein adsorption. In this work, we investigated the surface modification and performance of polyamide membranes by zwitterionic materials.To reduce the fouling of aromatic poly amides membrane, a hydrophilic polymer, poly(sulfobetaine methacrylate) (pSBMA), was grafted from the surface by surface-initiated atom transfer radical polymerization (ATRP). On the other hand, the secondary interfacial immobilization of Lys and pSBMA on nascent membrane were explored.. The results show:(1) The pSBMA modified membranes show an excellent resistance to protein adsorption. The amount of irreversible protein adsorption could be reduced to 2.9% of original membrane.(2)The flux showed less reduction than the original one when large fouling molecule (Humic Acid, Bovine Serum Albumin) solution filtrated by the modified membrane without affecting the rejection capability.(3)The water flux of the modified membrane could consistently maintain higher than original membrane with similar rejection rate to NaCl under high pressure.(4) It’s difficult to modify the membrane surface by pSBMA through the secondary interfacial modification because of the big molecule of pSBMA with only one amino-group.(5) The membranes modified by Lys through secondary interfacial modification show encouraging signs in protein resistance, membrane flux and rejection. After the Lys immobilized on membrane surface, the protein adsorption could reduce to 70% of original membranes. Moreover, the flux increased to about two times that of original with rejection reduced 3-10% of original.