Dual-functional underliquid superhydrophobic and superoleophobic stainless steel mesh decorated with Ni3S2 nanorods for continuous oil/water separation

Abstract

Frequent oil leakages and ever-increasing oily sewage have brought about serious damage to the ecological balance and human health. Therefore, effective and durable separation strategies and use of effective materials are highly desirable. In this work, a superwetting Ni3S2 coating was fabricated on stainless steel mesh (SSM) to achieve continuous oil/water separation. This mesh was superoleophilic in air but superhydrophobic and superoleophobic under oil and water. Once immersed in a liquid, oil/water droplets displayed large contact angles and lower adhesion. A bidirectional T-tube device integrated with two meshes at the two exit ends with inverse wettability was employed to separate oil/water mixtures. This system displayed high separation efficiencies and flux regardless of the oil density, and the separation efficiency was largely maintained after 100 cycles of separation. The same device could also separate immiscible organic solvents. Moreover, the Ni3S2@SSM showed photocatalysis to degrade water-soluble dyes targeting to further relief the water pollution. This multi-superwetting Ni3S2@SSM is expected to be a promising material for practical oil/water separation.