A robust and high-throughput superhydrophobic-superoleophilic Zn/Ni composite coating prepared on stainless steel mesh for oil-water separation

Frequent oil spills and the discharge of oily wastewater have adverse effects on the environment and ecosystems. Against the backdrop of escalating environmental concerns, developing high-performing and eco-friendly oil-water separation techniques is crucial. In this study, we successfully created a PFOTS-Zn/Ni superhydrophobic-superoleophilic coating, abbreviated as PZNM, by electroplating Zn²⁺ and Ni²⁺ on the stainless steel mesh, followed by modification with perfluorooctyltriethoxysilane-ethanol solution. The wettability test results show that the water contact angle (WCA) reaches 161.3°, with a water sliding angle (WSA) of 2°, and the oil contact angle (OCA) is approximately 0°. Subsequently, the PZNM samples were subjected to tests including blade scratching combined with sandpaper abrasion, tape peeling, bending tests, submerging in acidic and alkaline solutions, high-temperature gradient exposure, and electrochemical corrosion to verify their outstanding long-term durability. Most importantly, it can be shaped into a practical continuous oil-water separation device. In the oil-water separation test, it was found that the superhydrophobic-superoleophilic PZNM achieves highly efficient oil-water separation, with a water/n-hexadecane separation efficiency of up to 93.2 % and a water-chloroform separation flux of 6450±30 L·m⁻²·h⁻¹. The preparation process is straightforward and green, providing an economical solution. This design holds considerable prospects for applications in the domain of oil-water separation.