Densely grafting quaternary ammonium cation and salicylaldehyde on the APA-TFC membrane surface for enhancing chlorine resistance and anti-biofouling properties

摘要

For the sake of enhancing chlorine resistance and anti-biofouling simultaneously, the surface of an aromatic polyamide (APA) thin film composite (TFC) membrane was densely modified by quaternary ammonium cation (QAC) and salicylaldehyde (SA) in this work. The aza-Michael reaction was implemented on the APA-TFC membrane surface with the aid of dimethylaminoethyl methacrylate as a Michael receptor and the N-H groups belonged to amide, residual aromatic amines, and polyamides as Michael donors. Then, the dimethylamino groups of the APA-TFC membrane surface were furthermore converted into the QAC through the quaternarization of 5-chloromethylsalicylaldehyde. The experimental results showed that QAC and SA synergistically endowed the membrane with the durable anti-biofouling properties by acting as the anti-microbial agents and bacteria contact-killers, alternatively SA endowed the membrane with the high chlorine resistance as the chlorine-consumer, and QAC could also endow the membrane with the high hydrophilicity as the hydrophilic material. Under the optimized modifying conditions, the chlorine and biofouling had almost no influence on the water flux and salt rejection of the modified membrane during the filtration process fortunately.