Biofouling, as one of the membrane foulings, is the major

obstacle limiting the application of polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membranes in reclamation of wastewaters and

treatment of industrial fluids. Herein,

we introduced a facile and effective

strategy for the modification of traditional PA-TFC NF membranes

to improve water permeability and biofouling resistance. Specifically, three reactive guanidine molecules were successfully

bonded onto the surface of PA-TFC membranes using chemical reactions between

the amine groups of guanidine and the residual acyl chloride groups on the nascent

PA-TFC membrane. The covalent attachment of guanidines can significantly enhance water permeability without compromising salt

rejection. For instance, for 2 g L_1 Na2SO4 aqueous

solution, the water flux of NFM2 increased from 25.2 L m_2 h_1 to 68.4 L m_2 h_1 at 25 _C and 0.6 MPa compared to the traditional piperazine (PIP)–trimesoyl chloride (TMC) membrane, while around 98.3%. Na2SO4

rejection was

maintained. Moreover, the membranes were endowed with easy-cleaning properties,

which can remarkably prevent foulant adhesion, with the water flux recovery ratio being as high as 98.9%. The

developed TFC membranes also showed excellent anti-adhesive and antimicrobial

activities against Gram-negative Escherichia coli K12 (E. coli), Gram-positive Bacillus pumilus LDS33 (B.

pumilus) and Aspergillus

parasiticus JFS (A.

parasiticus). Therefore, the

resultant guanidinium-functionalized NF membranes which have integrated high

permselectivity and superior fouling resistance properties are promising

materials for fabricating a new generation of anti-fouling/antimicrobial

surfaces that are applicable to many applications such as water desalination

and softening and wastewater treatment.