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.