Preparation And Performances Of Anti-biofouling Reverse Osmosis Membranes

As an economical desalination technology,reverse osmosis(RO)membrane technology has been widely applied to many fields.However,RO membrane still has its challenges in the practical application.Membrane fouling have constrained the further development and application of RO membranes.To solve this problem,we prepared novel anti-fouling and anti-biofouling RO membranes by second interfacial polymerization.By second interfacial polymerization of chitooligosaccharide(COS)and nascent aromatic polyamide RO membranes,COS-modified membrane was prepared.The membrane surface became smoother and more hydrophilic(contact angle decreased from 60.3 ± 4.8 ° to 11.2 ± 3.2 °)after the COS grafting.The water flux of the COS-modified membrane increased 13.2 % than that of the virgin membrane,while the salt rejections of the membranes were nearly the same.Fouling tests illustrated that the COS-modified membrane exhibited improved anti-fouling property,with lower flux decline ratios and higher flux recovery ratios to negatively charged bovine serum albumin(BSA)and positively charged lysozyme compared to the virgin membrane.Moreover,the COS-modified membrane maintains its high permselectivity after being immersed in the Gram-negative Escherichia coli(E.coli)and Gram-positive Bacillus subtilis(B.subtilis)suspensions for 7 days.COS and dicyandiamide were used as raw materials to obtain biguanidine functionalized chitooligosaccharide(COSG)through microwave irradiation.Then COSG grafted onto nascent aromatic polyamide RO membranes surface by second interfacial polymerization.The water flux of the COSG-modified membrane increased 16.5 % than that of the virgin membrane,and the COSG-modified membrane exhibited high salt rejection.After fouling tests with BSA and lysozyme,the flux decline ratios of the COSG-modified membranes were lower than those of the virgin membranes.After the fouled membranes were cleaned,the flux recovery ratios of the COSG-modified membranes were more than 93 %,which were far higher than those of the virgin membranes.Besides,compared with the virgin membrane,the COSG-modified membrane exhibited higher anti-bacterial property against both the B.subtilis and E.coli(mortalities of 99.9 %).Moreover,the COSG-modified membrane maintains its high permselectivity after being immersed in the E.coli and B.subtilis suspensions for 7 days.