Creating superhydrophobic mild steel surfaces for water proofing and oil–water separation

A simple and inexpensive two-step immersion method is reported to make mild steel superhydrophobic. Micro–nano-scale roughness and surface chemistry modifications were created via immersing mild steel into a salt solution followed by treatment with a low surface-energy polymer. The fabricated mild steel has water contact angles greater than 150° and remarkable water bouncing properties. This method was also used to treat a mild steel mesh for oil–water separation. In this paper, a new, facile and reusable gravity-induced separation system is proposed to collect floating oil, the oil collection rate can reach >96%.