The PEGylation of plant polyphenols/polypeptide-mediated loose nanofiltration membrane for textile wastewater treatment and antibacterial application

Abstract In this study, a novel versatile composite NF membrane for textile wastewater treatment was reported. The e-Poly-L-lysine (e-PL) and natural material pyrogallic (PG) were co-deposited on negative charged hydrolyzed polyacrylonitrile (HPAN) substrate by Michael addition/Schiff base reaction. Then, the four-arm polyethylene glycol methoxy (4-arm-PEG) was firmly immobilized to form the “pine-shaped” structure on the surface of the modified HPAN substrate owing to the e-PL/PG-mediated surface, which was advantageous to PEG-binding. The membrane prepared at optimized condition (the mass ratio of e-PL to pyrogallic was 1:1 in coating solution and the concentration of 4-arm-PEG was 0.4 g/L) achieved a high permeability (76.3 L/(m 2  h MPa)), high rejection for dyes (methyl blue 98.9%) and low NaCl rejection (17%). Meanwhile, this membrane also possessed good hydrophilicity (35°), high removal rate of COD (89.1%), NH 3 N (84.5%) and satisfactory antifouling performance (flux recovery ratio 85%) in the long-term operation for actual textile wastewater. Besides, excellent antibacterial activity against E. coli and S. aureus was observed for the prepared membrane. Therefore, the prepared versatile loose composite NF membrane in this paper can be served as a potential competitor in textile wastewater treatment.