In situ fabrication dynamic carbon fabrics membrane with tunable wettability for selective oil–water separation

Abstract

Achieving reversible wetting properties of separation membrane for on-demand separate oil/water mixture remains challenging, especially for the oil/water mixtures with complex impurities. Herein, hierarchical porous dynamic separation membranes involving primary fiber membrane and secondary nanostructures are fabricated by in situ growth ZnO nanowires on the surface of carbon fibers. Based on the effect of oxygen-related defects of ZnO nanowires coating, the as-fabricated dynamic separation membrane is capable of switching wetting property between high-hydrophobicity and superhydrophilicity via simply annealing alternatively under vacuum and air environment, achieving the switching between oil-removing mode and water-removing mode according to the type of oil/water mixtures. Moreover, the dynamic separation membrane can be extended to separate the oil/water mixtures containing suspended solids using the reconstruction of ZnO dynamic coating. Through removing the ZnO dynamic coating via soaking the clogged membrane in the hydrochloric acid–ethanol and refabricating the ZnO-dynamic coating, the membrane blocked by impurities could be readily re-formed, which effectively expand its scope of application and enhance its anti-fouling property. This work not only provides a simple and on-demand solution for pure oily wastewater, but also extends the separation membrane to separate oil/water mixtures containing suspended solids.