Facile Preparation of Robust Superhydrophobic Stainless Steel Mesh Coated with Urushiol-based Polybenzoxazine and SiO2 for Efficient Oil/water Separation

Separating oil/water mixtures via superhydrophobic stainless steel mesh (SSM) is a kind of efficient methods of treating oily wastewater, and the superhydrophobic SSM with a low cost, simple fabrication process and robust usability remains a challenge. Herein, urushiol-based benzoxazine (U-D) with a strong substrate adhesion and low surface free energy was used to anchor SiO 2 particles on the SSM surface to obtain a durable superhydrophobic SSM (PU-D/SiO 2 /SSM) through a simple dip-coating process, meanwhile, epoxy resin was also introduced to further improve the adhesion between coating and SSM. PU-D/SiO 2 /SSM could successfully separate various immiscible oil-water mixtures with a separation efficiency of over 96% and a flux up to 27 100 L/m 2 h only by gravity, respectively. Especially, the modified SSM could effectively remove water from water-in-oil emulsion with a separation efficiency of 99.7%. Moreover, PU-D/SiO 2 /SSM had an outstanding reusability, whose water contact angle and separation efficiency only slightly decreased after 20 cycles of separating oil/water mixture. In addition, the modified SSM also displayed a satisfactory abrasion resistance, chemical stability and self-cleaning property. Thereby, the robust PU-D/SiO 2 /SSM prepared by cheap raw materials and facile dip-coating method exhibits a high potential for separating oil/water mixtures.