Superwetting and photocatalytic Ag₂O/TiO₂@CuC₂O₄ nanocomposite-coated mesh membranes for oil/water separation and soluble dye removal

A novel oily wastewater treatment strategy of simultaneously removing insoluble oily compounds and soluble organic pollutants is highly desirable. Herein, a hierarchical Ag₂O/TiO₂ heterojunction-loaded CuC₂O₄ nanosheet-decorated copper mesh (Ag₂O/TiO₂@CuC₂O₄ CM) was rationally designed by a combination of chemical etching and solvothermal deposition methods to implement the strategy. The Ag₂O/TiO₂@CuC₂O₄ CM with hierarchical nanostructures derived from hydrophilic CuC₂O₄ nanosheets and belt-like Ag₂O/TiO₂ heterojunction was proven to exhibit superior superhydrophilicity, underwater superoleophobicity, and photocatalytic ability, which greatly improved the antipollution ability of the substrate mesh. The as-fabricated mesh with a reasonable mesh number can efficiently separate oil/water mixtures with an ultra-high flux (∼70 kL m⁻² h⁻¹) and surfactant-stabilized oil-in-water emulsions with an ultra-low residue oil content in filtrate (<60 mg L⁻¹). More importantly, the loaded heterojunction on the CM showed a high photodegradation efficiency of about 94.1% toward soluble methylene blue and self-cleaning ability to regenerate oil-contaminated mesh within 60 min under visible light irradiation by photo-Fenton-like reaction. Besides, the favorable salt resistance, acid and alkali resistance, and stability of the CM for long-term use were also observed. Thus, this study provides a new way for the treatment of complex oily wastewater.