Preparation of underwater superoleophobic SiO 2 /CS/PVA coating on 304 stainless-steel mesh with excellent oil–water separation performance and stability

The wide application prospect of super-wetting materials in the field of oil–water separation has aroused extensive scholarly interest. With the aid of SEM, EDS, and FTIR, it was proved that the SiO 2 /CS/PVA underwater superoleophobic coating was successfully prepared by etching and dip coating. The surface of the coating formed a mountain-like microstructure and with the extension of etching time, the roughness of the mountain-like microstructure increased. After more than 10 min of etching, the roughness of microstructure was basically unchanged and the underwater OCA was as high as 160.3°. The results indicated that 10 min was the best time for etching reaction. The performance of oil–water separation was tested. The separation efficiency after 50 separation cycles was still more than 98.5%. The results showed that the coating had excellent oil–water separation performance and separation cycle characteristics. The stability of the SiO 2 /CS/PVA underwater superoleophobic coating was tested. After being placed in acidic solution, alkaline solution or air, the underwater OCA of the coating was higher than 155° and the oil–water separation efficiency was as high as 98%. The experimental results proved the excellent long-term and pH stability. In addition, the coating had self-cleaning ability and low adhesion performance, which can arrest oil phase pollution.