Superhydrophilic Al₂O₃ composite meshes for continuous high-efficiency oil-water separation

Superhydrophilic and underwater superoleophobic alumina composite meshes (Al₂O₃@Meshes) were prepared by two different methods: the in-situ growth method and the impregnation method. The in-situ growth method used aluminum powder to react with sodium hydroxide and formed cluster-like Al₂O₃ on the sintered wire mesh after calcination. As for the impregnation method, the sintered wire mesh was impregnated with the saturated aluminum nitrate solution and formed papillary Al₂O₃ on the mesh after calcination. The hydrophilic and rough Al₂O₃ were capable of forming a water layer and endowed Al₂O₃@Meshes with superhydrophilicity, which made the meshes to transport water but to intercept oil. The Al₂O₃@Meshes exhibited excellent separation efficiency for various oil-water mixtures even under low concentrations in the intermittent device. Meanwhile, the Al₂O₃@Meshes performed well in recyclability and thermostability for oil-water separation at high temperature (95 °C). Furthermore, the continuous oil-water separation was achieved by assembling Al₂O₃@Meshes on the fabricated device. A continuous device could separate oil-water mixtures efficiently over 80 L in the consecutive 12 h and the separation efficiency maintained over 99.8% at the whole process.