Robust Zwitterionic Poly(imidazolium)-Coated PVDF Membrane for Oily Water Treatment with Antibacterial and Anti-Biofouling Performances

Membranefouling remains a major challenge during oily wastewaterpurification, resulting in reduced water flux and separation efficiency.Zwitterionic polymers have been introduced to the PVDF membrane andshown their fouling resistance ability. However, most current zwitterionslack bactericidal effects and tend to be fouled by the attachmentof bacteria and biofilm formation in long-term service. Herein, asynthetic zwitterionic poly(imidazolium), poly(ZIM-co-VTS), was introduced onto the PVDF membrane by co-assembly withpolydopamine (PDA) and tetraethyl orthosilicate (TEOS) as a silicasource. The in situ covalent bond can be formed betweenthe catechol from PDA and silanol groups from both TEOS and imidazole-basedpolymers. Further, Fe3+ cross-linking contributes to therobust chemical stability of modified PVDF. The as-prepared coatingexhibits superhydrophilicity and underwater superoleophobicity underharsh conditions (pH = 1 and 13), remaining high separation efficiency(>99%) toward various surfactant-stabilized oil-in-water emulsionswithout an apparent water flux (>1013 L m(-2) h(-1) bar(-1)) decline. More importantly,the cationic imidazolium in poly(ZIM-co-VTS) enduesthe excellent bacterial killing efficiency toward Staphylococcusaureus (4.5 log(10) reduction) and Escherichia coli (4.7 log(10) reduction).The zwitterionic poly(imidazolium)-modified PVDF exhibited long-termdurability with anti-biofouling properties and was a promising candidatefor practical oily wastewater remediation.