L-Cysteine functionalized halloysite nanotubes/PVDF ultrafiltration membrane for improving anti-fouling performance

L-Cysteine is a hydrophilic zwitterionic amino acid, which contributes to the hydrophilicity and anti-fouling properties of the membrane. In this manuscript, an innovative nanocomposite (Cys-PDA-HNTs) was synthesized by spreading polydopamine on the outside of halloysite nanotubes (HNTs) as a secondary reaction platform and covalently grafting L-Cysteine by Michael addition reaction. A series of PVDF based ultrafiltration (UF) membranes were produced by mixing with different amounts of Cys-PDA-HNTs nanocomposite. XPS and FTIR were used to demonstrate the successful preparation of composite membranes, and their performance was characterized by WCA, water flux, BSA rejection ratio and anti-fouling measurements. It is found that M4 (with 1 wt% Cys-PDA-HNTs) had the greatest DI water flux (251.3 L.m(-2).h(-1)), lowest irreversible pollution ratio (18.5%), highest flux recovery ratio (81.5%) and the best long-term anti-protein fouling performance. This study offers a promising strategy to design novel UF membranes in the field of water purification.