Electrospun SiNPs/ZnNPs-SiO2/TiO2 nanofiber membrane with asymmetric wetting: Ultra-efficient separation of oil-in-water and water-in-oil emulsions in multiple extreme environments
Superwetting interfacial porous membranes with different wettabilities have enormous potential for wastewater treatment. The wettability of most smart separation membranes is controlled by external environmental factors such as temperature, pH, and pressure. In a constant environment, they have only one kind of wettability and can separate only one type of emulsion, and in multiple extreme environments, they become “unintelligent” and even lose their separation ability. Inspired by China's “Face-Changing in Sichuan Opera,” we have prepared a novel electrospun SiNPs/ZnNPs-SiO 2 /TiO 2 (SZST) nanofiber membrane by a calcining-spraying method. The obtained membrane can rapidly switch its wettability in various environments for the controllable separation of both oil-in-water and water-in-oil emulsions. The advanced electrospinning, combined with micro-nano hierarchical structures, greatly improved the wettability and porosity of the membrane, making the separation efficiency more than 99% stable. Additionally, the flux was maintained at about 2000 L/m 2 h. Interestingly, the separation efficiency showed almost no change in various harsh environments (e.g., strongly acidic and alkaline conditions, high or low temperatures, and even salty media), and the developed membrane exhibited excellent recyclability. In addition to good corrosion resistance and chemical stability, the membrane demonstrated excellent fire and frost resistance. Therefore, the SZST nanofiber membrane has great practical value in industrial production.
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