Superwetting sea urchin-like BiOBr@Co₃O₄ nanowire clusters-coated copper mesh with efficient emulsion separation and photo-Fenton-like degradation of soluble dye

The development of superwetting materials for the separation of oily wastewater and emulsified oil/water mixtures has been accelerated to handle the ever-increasing oil spills from industrial and sanitary wastewaters that contain organic contaminates (e.g., dyes). Herein, sea urchin-like BiOBr@Co₃O₄ nanowire clusters were fabricated on the copper mesh substrates via combination of hydrothermal synthesis and calcination of Co₃O₄ nanowire clusters, and hydrothermal deposition of a BiOBr photocatalyst. Such a hierarchical nanostructure composite membrane acquired superhydrophilicity and underwater superoleophobic properties, and consequently presented excellent self-cleaning and anti-fouling with an underwater oil contact angle of 160.6 ± 2°. The membrane had high emulsion separation efficiency and permeation flux for both surfactant-free (≥99.98%, up to 4656.33 L·m⁻²·h⁻¹) and surfactant-stabilized oil-in-water emulsions (≥98.66%, up to 887.67 L·m⁻²·h⁻¹). Moreover, the deposition of BiOBr enhanced the photo-Fenton-like catalytic activity so that the membrane could degrade ≥96.0% methylene blue (50 mL, 10 ppm) within 60 min under visible light irradiation. Furthermore, the as-fabricated superwetting mesh membrane demonstrated great reusability as well as good mechanical and corrosion resistance when exposed to harsh environmental conditions. Thus, this study presents a novel high-performance superwetting material with great potential in efficient removal of insoluble and soluble organic contaminants from oily wastewater.