Preparing a wettability-controllable stainless-steel mesh and its oil–water separation performance

Abstract

The ability to regulate and apply surface wettability has attracted much attention in the surface engineering field. In this study, a simple chemical etching method was used to construct a rough micro/nano structure on 304 stainless steel mesh; this rough surface was subsequently decorated with fatty acids of varying chain length to regulate wettability. The wettability, composition, and morphology of the surface were characterized and analyzed by measuring contact angles, and by atomic force microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy . The superhydrophobic and superoleophilic properties of the mesh modified with long-chain fatty acids were examined for oil-water separation performance and reusability. The surface had a micro/nano hierarchical morphology with ordered carbon chains, and the hydrophilic-to-superhydrophobic transformation was achieved by adjusting the chain length of the fatty acid to deliver contact angles in the range of 30°~154°. The oil contact angle was always 0°, irrespective of the chain length fatty acid, and oil drops quickly penetrated the mesh surface. A fatty acid with a longer chain afforded a more hydrophobic and oleophilic mesh surface and better oil–water separation efficiency (up to 96%), which still exceeded 85% after 50 cycles of oil–water separation testing. Consequently, the prepared surface with controllable wettability has excellent prospects for use in intelligent response interfaces and oil–water separation applications.