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 TiO 2 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. • Fabrication of Polycarbonate (PC) membrane using the NIPS method with PVP as an additive to enhance porosity and optimize membrane structure for oil-water separation • Incorporation of Tannic acid layer on the membrane surface using NaIO 4 oxidant and formation of an intermediate layer to coat the functionalized TiO 2 nanoparticles with Gallic acid, which increases the hydrophilicity and antifouling properties and ensures uniform distribution without agglomeration. • Developing an optimized membrane with high flux at near-zero operating pressure, excellent oil rejection, and strong fouling resistance, offering a cost-effective and eco-friendly solution for oily wastewater separation.