Fabrication of TiO2/SiO2 superhydrophobic coating for efficient oil/water separation

As the increasing discharge of industrial oily wastewater posed a severe threat to the ecological environment and human health, various oil/water separation technology has been proposed all over the world. In recent years, superhydrophobic film for oil/water separation has gained much more attention. A simple method was explored in this paper to prepare superhydrophobic TiO2/SiO2 nanoparticle coating with varied particle size and ratio. Superhydrophobic metal mesh, sponge and loofah were fabricated by simple spraying method. The topological structure and surface wettability of the prepared coating was characterized by SEM, TEM as well as contact angle measurements. The nano-scale pore structure and the convex nano-nipple structure were observed on the surface of the coating, which supply the microstructure evidence to explain its superhydrophobic characteristics, water contact angle (WCA) ≥ 155° and oil contact angle (OCA) ≈ 0°. The oil/water separation efficiency of the superhydrophobic coating with different substrates was around 95% during a series of experimental investigation for varied oil/water mixtures. In addition, the separation efficiency can remain above 90% after 60 separation cycles, which indicated the better sustainability of the coating. The developed materials with their stable hydrophobicity, recyclability, durable oil resistance and water resistance displayed potential application for oil/water separation in industry and daily life.