In Situ Growth of ZnFe-LDHs on Ti-Tannic Acid Coordination Polymers to Construct Superhydrophilic PVDF Oil/Water Separation Membranes with a Photoinduced Self-Cleaning Ability

This study demonstrates a novel two-step strategy to fabricate a polyvinylidene fluoride (PVDF) membrane with integrated superhydrophilicity, underwater superoleophobicity, and photoinduced self-cleaning capability. A mussel-inspired, adhesive, porous coordination polymer (PCP) was first synthesized from tannic acid and tetrabutyl titanate. ZnFe-layered double hydroxides (ZnFe-LDHs) were subsequently grown in situ on the PCP via coprecipitation to form a stable PCP/LDHs composite dispersion, which was then coated onto a commercial PVDF membrane. The prepared membrane exhibits a water contact angle approaching 0° and underwater–oil contact angles exceeding 150°. During separation tests, it demonstrated high efficiency of over 99.8% for various oil-in-water emulsions, achieving a high permeability of up to 4983 L m–2 h–1 bar–1. Leveraging the semiconducting properties of ZnFe-LDHs, the membrane effectively degrades adsorbed organic pollutants under light irradiation, restoring its antifouling properties and showcasing an excellent self-cleaning ability. This work provides a practical approach for designing high-performance, durable membranes for oily wastewater treatment.