Modified metal mesh with bipolar wettability for rapid and gravity-driven oil-water separation and oil collection

Oil contamination from oilfield geothermal water severely restricts the efficient utilization of geothermal energy. Oil-water separation pretreatment via removing oil from water may provide a kind of possibility to mitigate the oil pollution problem. Stainless steel filtration mesh with bipolar wettability was successfully fabricated to attempt the gravity-driven separation of various oil-water mixtures. The highly hydrophilic mesh was prepared by liquid phase deposition of TiO2, and the hydrophobic mesh was realized via the subsequent modification of fluorosilane on highly hydrophilic mesh deposited by TiO2. Only with relatively small pore size, the highly hydrophilic mesh and the hydrophobic mesh were applicable for separating oil-water mixtures. Besides, microscopic morphologies, surface chemical compositions, contact angles, water wetting behaviors, water-holding capacities, abrasion test and oil collection were also investigated. In general, the modified mesh with bipolar wettability presents gravity-driven oil-water separation for various oil-water mixtures, which may have potential industry application value such as the pretreatment of oilfield geothermal water.