The zein-based fiber membrane with switchable superwettability for on-demand oil/water separation

Abstract Zein, a type of natural material possessing adaptable wettability toward oil and water, is applied in on-demand oil/water separation. The SiO2/zein/PAN fiber membranes are fabricated by electrospraying zein/SiO2 spheres onto the electrospun zein/PAN fibers. The synergistic effects of the amphiphilic property of zein and the hierarchically micro-/nanostructured roughness surface endow the SiO2/zein/PAN fiber membrane with in-air superamphiphilicity, underwater superoleophobicity and underoil superhydrophobicity. The fiber membrane with switchable wettability selectively suitable for both in water and in oil circumstances is capable of on-demand oil/water separation upon prewetting the membrane surface with water and oil. The fiber membrane exhibits the separation performance with high separation efficiency and separation flux for both the oil/water mixtures and surfactant-stabilized oil/water emulsions. Benefitting from the hierarchical structures on roughness surface, the fiber membrane with excellent antifouling capability shows the good cyclic stability and reusability. Such a novel type of zein-based fiber membranes may offer exciting opportunities in on-demand oil/water separation and expand the applications of natural materials.