Fabrication of superhydrophobic nano-soil coated surfaces for oil/water separation and metal corrosion protection

Abstract

Low-cost and scalable fabrication processes are needed to prepare efficient superhydrophobic materials, particularly for oil/water separation and metal protection against severe oil spills and metal corrosion. Here, an effective oil/water separation mesh with long-lasting acid/base durability and corrosive resistance is reported. In this work, the mesh was fabricated by simply spraying nano soil particles cross-linked with melamine resin and impregnating them with polyethylene (PE) solution. The multi-layered morphology obtained from the spraying and impregnating process which provides the unique wetting properties for the stainless steel (SS) mesh, such as superhydrophobicity and low water adhesion. Also the low chemical activity of alkyl sp3 carbon-hydrogen bonds provides acid/base resistance for the manufactured material. By utilizing these unique properties, not only can gravity-driven efficient oil/corrosive fluid separation be achieved, but the fabricated superhydrophobic stainless steel (SSS) mesh retains high separation efficiency (> 99%) and superhydrophobicity (water contact angle, WCA > 150°) in reuse process of wastewater in treated oil. More importantly, this excellent protection can effectively reduce the corrosion rate of the mesh by more than two orders of magnitude (SS mesh icorr 1.82 × 10−8 A·cm−2; SSS mesh icorr 9.84 × 10−11 A·cm−2) which providing a long-lasting protection even after 16 days of immersion in 3.5 wt% NaCl solution. All in all, the easy operation, acid/base resistance, high separation efficiency, and corrosion inhibition efficiency of the SSS mesh give them great potential for oil/water separation and metal protection applications.