Superhydrophilic-underwater superoleophobic TiO2-coated mesh for separation of oil from oily seawater/wastewater

Oil/water separation is a topic of interest worldwide because of increasing release of industrial oily wastewater and frequent leakage of crude oil. Superhydrophilic and underwater superoleophobic meshes were fabricated by simple and fast dip-coating of nanosized TiO2 on a stainless steel mesh with a 50 mu m pore size. The coated mesh was used for oil/water separation by gravity-driven filtration without additional energy. After acid treatment and TiO2 coating of the mesh, its surface property was altered from hydrophobic to superhydrophilic and superoleophobic. Oil/water separation was achieved in 3 s with an efficiency of 98-99%, irrespective of oily water type (seawater or wastewater). Initial separation efficiency was maintained during a test involving 20 recycles. Therefore, the as-made TiO2-coated mesh can be used in practical applications such as for wastewater purification, and in the petroleum industry.