Multifunctional Membranes for Simultaneous Oil/Water Separation and Organic Pollutant Removal: A Review

Oily wastewater commonly contains dissolved organic contaminants such as dyes, antibiotics, and phenolic compounds. Conventional stepwise treatment processes involve complex operation, high energy consumption, and severe membrane fouling. Multifunctional membranes integrating oil/water separation, pollutant adsorption or catalytic degradation, and membrane self-cleaning provide a promising solution for treating complex oily wastewater. This review summarizes recent advances in multifunctional membranes based on metal oxides, two-dimensional (2D) materials, three-dimensional (3D) porous structures, and biomass-derived materials. Key strategies, including micro and nanoscale structure regulation, wettability control, interlayer channel optimization, heterojunction construction, and active site engineering, are discussed together with the synergistic mechanisms involving oil/water separation, adsorption enrichment, photocatalysis, and Fenton reactions. Approaches for improving membrane flux, separation efficiency, degradation activity, antifouling performance, and cycling stability are also reviewed. Finally, challenges related to scalable fabrication, adaptability to real wastewater, long-term stability, and standardized evaluation are outlined, providing guidance for the design and practical application of multifunctional membranes.