Membrane separation technology is an important method of treating oily wastewater with great potential for development. However, preparation of membranes for efficiently separating complex oil-water mixtures continues to be challenging. In this study, a strategy for efficient construction of asymmetric wetting surfaces was designed, and successfully prepared an asymmetric super wetting Janus polyvinylidene fluoride (PVDF) modified separation membrane to separate complex oil-water emulsion. The composite PVDF membrane was prepared using a non-woven fabric substrate and phase conversion method. Subsequently, composite membrane was rapidly hydrophilic modified on one side using tannic acid and 3-aminopropyltriethoxysilane under the strong oxidizing effect of oxidant sodium periodate. Then non-woven fabric substrate was peeled off to obtain a Janus PVDF modified separation membrane. The front and back sides of the separation membrane have highly asymmetric micromorphology and wettability. The front side has hydrophilic/underwater oleophobic wettability (with a water contact angle of 31°). The separation efficiency of oil-in-water emulsion is up to 99.5%, while the back side has super lipophilic/underoil hydrophobic wettability (with a water contact angle of 131°). The separation efficiency of water-in-oil emulsion is up to 98.6%, improving the efficiency of oil in water separation and application range.

中文翻译：

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无纺布基材上简单方法制备的非对称超润湿Janus PVDF油水分离膜


膜分离技术是处理含油废水的重要方法，具有巨大的发展潜力。然而，制备用于有效分离复杂油水混合物的膜仍然具有挑战性。本研究设计了高效构建非对称润湿表面的策略，并成功制备了非对称超润湿Janus聚偏二氟乙烯（PVDF）改性分离膜来分离复杂的油水乳状液。采用无纺布为基材，采用相转化法制备复合PVDF膜。随后，在氧化剂高碘酸钠的强氧化作用下，利用单宁酸和3-氨丙基三乙氧基硅烷对复合膜的一侧进行快速亲水改性。然后将无纺布基材剥离，得到Janus PVDF改性分离膜。分离膜的正面和背面具有高度不对称的微形貌和润湿性。正面具有亲水/水下疏油润湿性（水接触角为31°）。水包油乳液分离效率高达99.5%，背面具有超亲油/油下疏水润湿性（水接触角131°）。油包水乳液分离效率高达98.6%，提高了油水分离效率和应用范围。