Superhydrophilic fish-scale-like CuC2O4 nanosheets wrapped copper mesh with underwater super oil-repellent properties for effective separation of oil-in-water emulsions

The development of efficient, facile and stable approach to separate water from oilfield emulsified oily wastewater is highly desired. In our work, inspired by oil-repellent property of fish scales with a thin layer of mucus and hierarchical structures, pioneering fish-scale-like CuC2O4 nanosheets wrapped (i.e., CuC2O4 NSW) on copper mesh surfaces were fabricated by a facile in-situ chemical etching. The unique vertically grown crisscross CuC2O4 nanosheet layer delivered a strong water capture ability to form a firm water film for achieving rapid and super oil repellence functionality. The 300-mesh CuC2O4 NSW copper mesh exhibited superior underwater superoleophobicity and was proven to treat emulsified oily wastewater effectively (with a water permeation flux being circa 2200 L·m−2·h−1 and COD value in filtrate at circa 54 mg·L−1). Furthermore, the 500-mesh CuC2O4 NSW copper mesh was demonstrated to effectively separate surfactant-stabilized oil-in-water emulsions (with a water permeation flux of 1000–2000 L·m−2·h−1 and COD value in filtrate < 55 mg·L−1). The good chemical, mechanical and thermal stability of the as-prepared mesh was further ascertained by different stability tests. With the efficient separation capability, good underwater super oil-repellent and self-cleaning abilities, the novel membrane prepared by the easily scaled-up method shows great potential for industrial applications.