Preparation of super hydrophilic-underwater super oleophobic photoinduced self-cleaning Al₂O₃ @TiO₂ ceramic membrane and separation performance of oil-in-water emulsion

Membrane hydrodynamic irreversible oil fouling is a pressing issue. Here, an antifouling Al₂O₃ @TiO₂ membrane with excellent wettability was created using the sol-gel method to create an anatase nano-TiO₂ coating on the surface of an Al₂O₃ ceramic membrane. Analyzing the separation performance of an Al₂O₃ @TiO₂ membrane on simulated oily emulsions determined the amount of TiO₂ covered on the membrane surface (0.8 mol·L⁻¹). Under the synergy of hydrophilic nano-TiO₂ and ultraviolet (UV) light, the Al₂O₃ @TiO₂ membrane demonstrated improved wettability and self-cleaning ability and maintained favorable separation performance (769.23 L·m⁻²·h⁻¹, 97.75%, 1.23 mg·L⁻¹) after 6 h of continuous separation of the actual oilfield produced water. After 30 min of UV illumination, the membrane flux recovered completely. This is due to the fact that the active substances (eg.,·OH,·O_2, and ¹O₂) generated in situ on TiO₂ on the membrane surface after UV illumination weakened the interaction of membrane surface fouling, resulting in less oil fouling. In addition, the Al₂O₃ @TiO₂ membrane maintained extremely outstanding oil resistance stability and recoverability during high-intensity hydraulic flushing and 25 cycles of testing. This study provides a theoretical basis for the engineering application of ceramic membranes in oilfield-produced water treatment.