Cellulose is a widely used hydrophilic material due to its rich hydrophilic hydroxyl groups. However, the presence of its lipophilic segment will affect the antifouling performance. Finding strategies to improve this problem has attracted considerable attention. In this work, a layer of silica was applied to a cellulose-deposited polyvinylidene fluoride membrane through a straightforward in-situ bionic silicification process of tetraethyl orthosilicate. The contact angle and oil droplet contact test proved that the high-hydrophilicity and underwater superoleophobicity of the silicified membranes were significantly enhanced. The surface structure and composition were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results of show that this improvement was mainly attributed to the presence of silicon hydroxyl groups, buried cellulose chains, and micro-nanostructures composed of cellulose and silica. The stable silica coating also provided protection for the polymeric membrane against degradation after water washing for 24 h, ultrasonic treatment (40 KHZ) for 10 min or exposure to different pH levels (pH=1, 4, 9 and 12) and saturated sodium chloride solution for 24 h. Furthermore, the silicified membrane showed outstanding oil adhesion resistance and permeation flux, enabling effective purification of different oil-in-water emulsions that were stabilized by emulsifiers. Notably, the membrane achieved a high oil removal rate (> 99.4 %) of various emulsions (toluene-in-water, cyclohexane-in-water, tetrachloroethane-in-water, soybean oil-in-water, toluene-in-salt solution, toluene-in-acid solution and toluene-in-alkaline solution emulsions). In particular, for toluene-in-water emulsions (oil droplets in the emulsion ranged from 58.77 nm to 615.1 nm), a significantly enhanced permeation flux (4777 L·m·h·bar) was obtained at 0.8 bar pressure. Even after multiple cycles of separation, the flux was higher than that of the unsilicified membrane. Overall, this approach is mild, simple, efficient, and easily scalable, making it an ideal method for producing superhydrophilic coatings with substantial application potential.

中文翻译：

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纤维素介导的 PVDF 膜的仿生表面硅化显着增强超亲水性和抗油粘附性，实现超快油/水乳液分离


纤维素因其丰富的亲水羟基而成为一种广泛应用的亲水材料。但其亲脂链段的存在会影响防污性能。寻找改善这一问题的策略引起了相当多的关注。在这项工作中，通过原硅酸四乙酯的简单原位仿生硅化工艺，将一层二氧化硅施加到纤维素沉积的聚偏二氟乙烯膜上。接触角和油滴接触测试证明硅化膜的高亲水性和水下超疏油性显着增强。通过扫描电子显微镜、傅里叶变换红外光谱和X射线光电子能谱分析了表面结构和成分。结果表明，这种改善主要归因于硅羟基、埋入式纤维素链以及由纤维素和二氧化硅组成的微纳米结构的存在。稳定的二氧化硅涂层还可以保护聚合物膜在水洗 24 小时、超声波处理 (40 KHZ) 10 分钟或暴露于不同 pH 水平 (pH=1、4、9 和 12) 和饱和氯化钠后不发生降解溶液放置24小时。此外，硅化膜表现出优异的抗油粘附性和渗透通量，能够有效净化乳化剂稳定的不同水包油乳液。值得注意的是，该膜对各种乳液（水包甲苯、水包环己烷、水包四氯乙烷、水包大豆油、盐包甲苯）实现了高除油率（> 99.4 %）溶液、甲苯酸溶液和甲苯碱溶液乳液）。 特别是，对于水包甲苯乳液（乳液中的油滴范围为 58.77 nm 至 615.1 nm），在 0.8 bar 压力下获得了显着增强的渗透通量（4777 L·m·h·bar）。即使经过多次分离循环，通量仍高于未硅化膜。总体而言，这种方法温和、简单、高效且易于扩展，使其成为生产具有巨大应用潜力的超亲水涂层的理想方法。