Fabrication of hydrophilic and underwater superoleophobic SiO2/silk fibroin coated mesh for oil/water separation

Abstract

Anti-fouling silk fibroin (SF)-silicon dioxide (SiO2) nanocomposites membrane is fabricated by spraying composite on the stainless steel mesh. The optimal membrane with water contact angles (CAs) of 10° and oil CAs of 150° exhibited superior stability, underwater superoleophobicity, ultralow oil-adhesion and wear resistance, and hence it could separate the diesel/water mixture with high efficiency of 99.7%. The separation efficiency of other oils (kerosene, petrol, hexane) is also above 99.1%. In addition, after 50 cycles, the mesh still maintains high separation efficiency, which is larger than 98.6%. Meanwhile, the as-prepared meshes can not only separate oil-water mixtures in a mild environmental condition, but also can effectively function in harsh environments (including high salt concentration and extreme pH values). The prepared mesh has strong mechanical stability, and its underwater superoleophobicity is stable after long-term exposure to the air, rendering it promising for actual oil-water mixture separation applications.