Fabrication of robust superhydrophobic–superoleophilic mesh for oil–water separation

Frequent oil spillage at sea and waste oily water draining cause severe harm to the environment and economy. Although various extremely wettable materials are designed to achieve oil–water separation, there are still limitations, such as expensive materials, fluorine-containing reagents and poor robustness of oil–water-separating materials. Here, the authors resolved the aforementioned problems by proposing a simple and low-cost sandblasting plating method with nickel (Ni), phosphorus (P) and 1-octadecanethiol modification to manufacture a robust superhydrophobic stainless steel mesh for separating oily water under harsh environments. The mesh can separate light and heavy oily water with outstanding separating efficiency and high purity. It can be also used to separate hydrochloric acid (HCl) solution–oil, sodium hydroxide (NaOH) solution–oil and sodium chloride (NaCl) solution–oil, with separating efficiency higher than 95%. Moreover, the mesh is still superhydrophobic and has outstanding oil–water-separating efficiency after sandpaper abrasion, tape stripping, simulated seawater corrosion and natural environment corrosion tests. Therefore, the robust superhydrophobic stainless steel mesh proposed in this work can very efficiently separate oily water in harsh environments.