Antifouling enhancement of polyimide membrane by grafting DEDA-PS zwitterions

In order to improve the water flux and antifouling property of polyimide (PI) membrane, zwitterions are grafted on PI membrane surface via a two-step modification route by reactions with N,N-diethylethylenediamine (DEDA) and 1,3-propane sultone (PS) sequentially. The reaction mechanism and physicochemical properties of membranes are confirmed via various characterization techniques. The anti-biofouling performance of the zwitterion-grafted PI membranes is evaluated by bacterial suspension immersion tests in Escherichia coli (E. coli) and staphylococcus aureus (S. aureus) solutions. The antifouling property is assessed via the filtration test using the bovine serum albumin (BSA) and dodecyl trimethyl ammonium bromide (DTAB) aqueous feed solutions. The effect of the reaction time with DEDA in the zwitterion-grafted process on the antifouling property is further investigated systematically. The results show that both the anti-biofouling and antifouling performances of zwitterion-grafted PI membranes are significantly improved.