Continuous Separation of Oil/Water Mixture by a Double-Layer Corrugated Channel Structure with Superhydrophobicity and Superoleophilicity

Abstract Superhydrophobic materials can rapidly separate oil/water mixtures, however, their engineering applications are rare owing to the lack of an appropriate design. In this work, a double-layer corrugated channel (DCC) structure with a superhydrophobic/superoleophilic stainless steel mesh (SSSM) is designed for continuous oil/water separation. The DCC exhibits stable operation for 15 days, with an oil recovery rate can reach 99.9%. The oil content of the separated water is less than 10 mg/L, and the chemical oxygen demand is less than 15 mg/L. The residual water content of the oil phase is only 2.68 × 10-4%. The results confirm that only oil penetrates the SSSM upper layer, flows laterally, and is collected through the side wall of the DCC. Water is confined in the channel and flows until it is discharged. The oil/water separation efficiency depends mainly on the oil residence time in the channel, which is determined by the oil mixture conditions, including concentration and flow rate, and by the channel geometry, including channel length, height, and width. The design provides a superhydrophobic material that is suitable for large-scale industrial oil/water separation.