Design, Development, and Outlook of Superwettability Membranes in Oil/Water Emulsions Separation

Abstract Oil leakage and discharge of industrial organic solvents are the main reasons for the oily wastewater. The separation of oil/water emulsions has been a global challenge due to the small particle size of the emulsions and their stabilities. An effective method is needed to resolve these issues. Superwettability membrane method has demonstrated a high separation efficiency, fast separation speed, low energy consumption, good scalability, easy operation, and recyclability. In essence, the special wettability of material is mainly determined by two factors: the chemical compositions of material surface and the surface morphology. Herein, in this review, the development of special wettability separation membranes is discussed including different preparation methods, and material preparation, such as superhydrophobic/super lipophilic, superhydrophilic/underwater superoleophobic, superlipophilic/superhydrophobic under oil, smart membranes with switchable wettability, and special wettability membranes with self‐healing or self‐cleaning property. The representative works of each part are introduced, focusing on preparation methods, innovations and separation performance of membranes. Finally, challenges and future directions in this field are also described.