Facile and scalable preparation of superhydrophobic brass mesh for efficient and rapid separation of oil and water

A facile method for preparing superhydrophobic brass mesh is proposed based on electrochemical etching and surface modification. The impact of processing time and the electric potential of the electrochemical etching were studied on the contact angle (CA) of the mesh. The samples were examined using scanning electron microscopy, Energy-dispersive X-ray spectroscopy analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. The electrochemical etching process caused the decrement of wires' thickness and imposed roughness. Results showed more dissolution of zinc than copper under 3 V of the electric potential and the processing times of 3 and 6 min. The optimum condition of electrochemical etching was obtained under the electric voltage of 3 V for a processing time of 6 min, which led to a CA of 155.5 +/- 3.2 degrees. The thickness of the mesh wires decreased by 17.7% due to electrochemical etching in this sample. This sample also showed low adhesion for a water drop. The efficiency of oil/water separation was above 95 for the xylene and ethyl acetate in a batch system. The effect of the flow rate of the oil-water mixture on separation efficiency was also examined. The optimum flow rate was 0.8 ml s-1 with a high separation efficiency of 96.8% for xylene/oil separation.