Dual-functional tight ultrafiltration membrane constructed from aminoquinone networks for sufficient dye/salt selectivity and bacterial inactivation

Membranes used for the treatment of highly saline textile wastewater generally suffer from low dye/salt selectivity and biofouling issues. Herein, the facile assembly of vanillic acid/ε-polylysine-based aminoquinone networks (AQN) on a porous PES substrate is proposed for the construction of a dual-functional tight ultrafiltration membrane with high dye/salt separation efficacy and superior antimicrobial functionality. By regulating the assembly duration, the surface structure and properties (i.e., thickness, roughness, hydrophilicity and pore size) of the composite AQN coating can be precisely tailored. Specifically, the optimized AQN-60 tight ultrafiltration composite membrane (MWCO of 3450 Da) experienced >98.50 % dye rejection and <3.56 % NaCl rejection for various dye/salt mixtures. Additionally, the prepared AQN-60 composite membrane demonstrated stable fractionation performance with an eventual dye rejection of 98.70 % and salt rejection of 3.98 % after 24-h filtration of a reactive blue 2/NaCl mixed solution. Furthermore, the integration of ε-polylysine onto the AQN-60 composite membrane markedly enhanced the antimicrobial ability of the tight ultrafiltration membrane, which showed good inhibition efficiency (98.75 %) against E. coli bacteria.