Photocatalytically Driven Self-Cleaning and Underwater Superoleophobic Copper Mesh Modified with Hierarchical Bi₂WO₆@CuO Nanowires for Oil/Water Separation

Abstract

Oily wastewater derived from oil spill accidents and illegal discharge of oil-related industries has brought an enormous challenge to the ecosystems and economic development. Herein, hierarchical Bi2WO6@CuO nanowire arrays (NWA) were grown on the surfaces of copper meshes by a combined process of chemical oxidation and hydrothermal deposition to introduce superwetting and self-cleaning functionality for highly efficient separation of oil/water mixtures. The resultant Bi2WO6@CuO NWA-coated copper meshes exhibited superior underwater superoleophobicity and separation ability with a water flux of around 60 kL·m–2·h–1 and oil residue in the filtrate water less than 15 ppm. Under visible-light illumination, the as-fabricated copper mesh was demonstrated to possess excellent photocatalytic oxidation ability to decompose oily contaminants to achieve self-cleaning for repeated usage. Various stability tests such as thermal resistance, salt and acid/alkali corrosion, and abrasion tests were conducted to ascertain the thermal, physiochemical, and mechanical durability and stability in practical applications. Thus, the Bi2WO6@CuO NWA-coated inorganic metal mesh is a potentially promising candidate for oily wastewater treatment owing to its high separation efficiency, visible-light-driven self-cleaning ability, and high environmental stability.