Anti-fouling PVDF composite membrane with SBMA@AgNPs hybrid separation layer: Fabrication, performance and organic-inorganic coupling synergistic enhancement antifouling mechanism

In this study, the flat-sheet membrane of polyvinylidene fluoride (PVDF)/polystyrene-maleic anhydride (SMA) was fabricated via the thermally induced phase separation (TIPS) technique. Subsequently, a dual-functional anti-fouling hybrid separation layer was developed by co-immobilizing zwitterionic SBMA and silver nanoparticles (AgNPs) onto the polymer membrane upper surface through Michael addition reaction and in-situ dopamine generation method. An organic-inorganic hybrid layer exhibiting dual resistance to both protein fouling and microbial fouling was constructed via the "SBMA-AgNPs" synergistic modification strategy. Furthermore, the antifouling mechanism and performance of the membrane system were systematically investigated. The results demonstrated that when BSA and Escherichia coli (E. coli) were employed as organic and microbial foulant models respectively, the membrane loaded with both zwitterionic SBMA and inorganic AgNPs achieved a flux recovery ratio (FRR) of 96.8 % and antibacterial efficiency exceeding 99.9 %, significantly outperforming membranes loaded with only either AgNPs or SBMA. Meanwhile, the irreversible resistance during operation reduced to 4.5 % and the pure water flux (PWF) decay rate reduced to 20.7 %. Finally, based on the evaluation of the long-term stability and FRR of post-backwashing, the synergistic enhancement anti-fouling mechanism of "organic-inorganic" coupling was elucidated by combining the hydration layer theory of zwitterionic SBMA and the antibacterial mechanism of AgNPs. This study offers novel insights and approaches for the future advancements of water treatment membrane technology.