Surface-modified porous polycarbonate membrane with tannic acid anchored by functionalized TiO2@GA for efficient oily water separation

Oily wastewater poses substantial environmental challenges. To address the accumulation of organics and contaminants on the membrane surface and the reduced lifespan of membranes, in this study, a novel surface modification strategy was developed involving the deposition of tannic acid (TA) as an intermediate layer on polycarbonate (PC) membranes, followed by the incorporation of gallic acid (GA)-functionalized TiO₂ nanoparticles (NPs). This hybrid coating enhanced the surface hydrophilicity and antifouling properties by preventing NPs agglomeration and ensuring uniform distribution. Characterization confirmed improved surface properties, including higher wettability, with a lower water contact angle of 16.5°and an underwater oil contact angle (158.9°). The optimized membrane demonstrated exceptional performance, achieving an oil/water separation flux of 310.11 L/m².h, 99.72 % oil rejection, and an excellent fouling recovery ratio (FRR) of 93.77 % at a near-zero operating pressure. These findings suggest that an eco-friendly, low-cost, high-performance modified membrane is desirable for oil-water separation in industrial applications with limited facilities.