Facile and effectual surface modification of polyacrylonitrile (PAN)-based ultrafiltration membranes via manipulating the synergistic interaction of dopamine and enzymes

Abstract

A drastic improvement in the overall permeability and antifouling performance was observed for the polyacrylonitrile (PAN) ultrafiltration (UF) membrane by the co-incorporation of dopamine (DA), protease (E1), and lipase (E2) in a facile multi-step synthetic scheme. SEM was utilized to indicate the successful formation of modifying layers on the membrane surface, whereas ATR-FTIR and zeta potential were used to provide deeper insight into the membrane surface chemistry. AFM and contact angle were used to assess the membrane's surface roughness and hydrophilicity, respectively. The optimally modified membrane surface was found to be quite hydrophilic, as indicated by the water contact angle value (39.8 ± 0.8°), and water flux across the membrane of 78.09 ± 1.6 kg/m2·h. Simultaneously, natural organic matter (NOM), including milk powder (MP), bovine serum albumin (BSA), and humic acid (HA), were efficiently removed, resulting in 99.9, 92.5, and 80.5 % removal efficiencies, respectively. Notably, the enzyme-immobilized membrane demonstrated outstanding antifouling performance as well as long-term stability. The dynamic anti-NOM fouling studies indicated that the surface modification was potentially capable of overcoming the tradeoff between membrane permeability and selectivity, resulting in FRR values of >90 %. The antibacterial properties of the surface-modified membranes against E. coli and S. aureus were also explored, and the optimal enzyme-immobilized membrane was found to be substantially antibacterial. Overall, this study aims to pave the way for the development of sustainable chemistry in designing innovative and highly efficient membranes.