An Al2O3@ZnO membrane for oil-in-water emulsion separation with photocatalytic regeneration prepared via a simple deposition route

Water resources are polluted by a large amount of oil, and the inorganic ceramic membrane separation technology for purification of the oil-in-water emulsion became a key research trend. Exploring and using composite ceramic membranes prepared by introducing functional materials was a new strategy to solve oil-in-water pollution. In this paper, a sea urchin-like nano zinc oxide (ZnO) was prepared using a simple and costeffective water bath method. The oil could be degraded by the urchin-like nano ZnO under UV and simulated sunlight, and the degradation efficiency was 82 % in UV light, higher than in simulated sunlight. An Al2O3@ZnO membrane was formed by depositing urchin-like nano ZnO on an alumina support, which demonstrated hydrophilicity in the air, superoleophobicity underwater, and pure water permeability of 4875.1 h(- 1)& sdot;m(- 2)& sdot;bar(-l). Under 0.4 bar, for separating sunflower seed oil-in-water emulsion of 1000 mg & sdot;L- 1, the stable permeation flux was 230.79 L & sdot;h(- 1)& sdot;m(- 2), and the separation efficiency was 98.26 %. After four cycles of regeneration, the final permeate flux stabilized at 171.7 L & sdot;h(- 1)& sdot;m(- 2) and the separation efficiency was 96.9 %, the Al2O3@ZnO membrane could be easily regenerated under UV light. This work demonstrated a new Al2O3@ZnO membrane for separating oil-in-water emulsions, featuring easy regeneration in UV light, representing a sustainable and environmentally friendly approach for oily wastewater treatment.