Nacre-inspired mineral-hydrogel PVDF membrane with superhydrophilicity, antifouling and antimicrobial properties for food oily wastewater treatment

Membrane fouling caused by oil droplets and organic contaminants remains a significant challenge in food oily wastewater treatment. Inspired by nacre's architecture, a superhydrophilic PVDF-PCT-Cu membrane was fabricated via a combination of deposition with polydopamine, carboxymethyl chitosan and tetrabutyl titanate and mineralization with Cu²⁺. The membrane exhibited superhydrophilicity (water contact angle: 0°) and underwater superoleophobicity (underwater oil contact angle: 152.65° ± 0.88°). It achieves high permeation fluxes (290.20-342.71 L m^-2 h^-1) and separation efficiency (98.34-99.78 %) for four oil/water emulsions (soybean oil, corn oil, blended oil, and rapeseed oil). PVDF-PCT-Cu membrane also demonstrated excellent antioilfouling performance (flux recovery rate: 91.19 %), chemical stability across acidic, alkaline, and saline conditions, and strong antimicrobial activity against Escherichia coli and Staphylococcus aureus. In treating actual food oily wastewater, PVDF-PCT-Cu membrane achieved over 90.87 % separation efficiency, significantly reducing pollutants and improving clarity, showing great potential for food oily wastewater treatment.