Hierarchical WO3@Cu(OH)2 nanorod arrays grown on copper mesh with superwetting and self-cleaning properties for high-performance oil/water separation

To realize highly efficient oil/water separation of inorganic metallic membranes for potential industrial application, hierarchical WO3@Cu(OH)2 nanorod arrays (NRA) were grown on copper mesh surfaces by combination of facile chemical oxidation and hydrothermal deposition. The WO3@Cu(OH)2 NRA-coated mesh was endowed with superhydrophilic, underwater superoleophobic and photocatalytically-driven self-cleaning functionalities to effectively separate oil and water from kerosene/water mixture, oilfield wastewater, and surfactant-stabilized emulsion. Results demonstrated that the water flux of surfactant-stabilized emulsion was up to 1.29 kL m−2 h−1 and the oil residues in filtrate was about 50 mg L−1. The visible-light-driven self-cleaning ability of the as-fabricated mesh was verified by the restored superwettability upon 80-min irradiation of visible light. Meanwhile, the WO3@Cu(OH)2 NRA coatings on copper mesh surfaces was found to maintain high stability and durability under extreme environment conditions, such as immersion tests in salt, acidic and alkaline solutions, high temperature and mechanical abrasion tests. With the inherent merits of high separation efficiency photocatalytically-activated self-cleaning and high stability, the as-fabricated WO3@Cu(OH)2 NRA-coated copper mesh is a potentially promising type of inorganic membranes for the treatment of oily wastewater in practical industrial fields.