Improving Antifouling Properties Of Reverse Osmosis Membrane Based On Polydopamine Coating Modification

As an important water treatment technology,reverse osmosis(RO)membrane technology faces membrane fouling in its application and development.Developing anti-fouling RO membrane is an important solution to alleviate membrane fouling.In this paper,anti-adhesion and anti-adhesion/antibacterial RO membranes were prepared based on functional polydopamine(PDA)coatings,with hydrophilic polymer brushes and hydrophilic bactericidal substances introduced on the membrane surface.With the polydopamine layer as the intermediate layer,the atom transfer radical polymerization(ATRP)initiator was introduced onto the membrane surface by the reaction of dopamine(DA)with 2-bromoisobutyryl bromide(BIBB),and then the acrylic polymer brushes were grafted to prepare the anti-adhesion membrane.By adjusting the concentration of DA and BIBB,the influence of fixed initiator on membrane permselectivity was reduced.After modification with polyacrylic acid,the roughness of the membrane surface was reduced,the water contact angle was reduced to 32.1±1.4°,the wettability/hydrophilicity was enhanced,and the surface was more negatively charged.After 30 minutes of ATRP polymerization,the flux of the optimal modified membrane was 27.8% higher than that of the virgin membrane,and the rejection was reduced.In the pollution experiment using bovine serum albumin(BSA)and lysozyme as the model pollutants,the flux reduction rate of the optimal modified membrane and the flux recovery rate after cleaning were better than those of the virgin membrane,showing a good anti-adhesion performance.After depositing PDA on the surface of the RO membrane by a simple oscillation method,the strong multiple hydrogen bonding between PDA and polyvinylpyrrolidone(PVP)was used to bind PVP,thereby further complexing the sterilization iodine(I)to prepare anti-adhesion and antibacterial RO membranes.The surface morphology of the PVP-I modified membranes did not change much compared with the virgin membranes,while the roughness increased,the water contact angle was reduced to 54.1±1.7°,the wettability of the membranes surface increased,and the negative charge decreased.Compared with the virgin membrane,the water flux of the modified membrane decreased by 4.3%,and the rejection remained basically unchanged.The modified membranes showed good anti-adhesion performance for both BSA and lysozyme,and its killing effect on Escherichia coli and Bacillus subtilis reached 99.9%.