Nanowire-Haired Inorganic Membranes with Superhydrophilicity and Underwater Ultralow Adhesive Superoleophobicity for High-Efficiency Oil/Water Separation
Nanowire-Haired Inorganic Membranes with Superhydrophilicity and Underwater Ultralow Adhesive Superoleophobicity for High-Efficiency Oil/Water Separation
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DOI：
10.1002/adma.201301480
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发表时间：
2013-08-14
影响因子：
29.4
通讯作者：
Jiang, Lei
中科院分区：
文献类型：
--
作者：
Zhang, Feng;Zhang, Wen Bin;Jiang, Lei
随着工业含油废水排放的增加和原油泄漏的频繁发生，油水分离已成为一个世界性的课题传统的油水分离技术，如气浮、重力分离结合撇油、吸油材料、混凝、絮凝等，受分离效率低、能源成本低、分离仪器复杂等限制，不能有效分离水中的微小油滴，需要进一步处理超滤（UF）等聚合物定向过滤膜已成功地应用于外部压力驱动下表面活性剂稳定的水包油乳液的分离但过滤膜最严重的缺陷是由于油吸附和/或油滴堵塞孔隙，导致通量低，渗透率下降快，从而导致严重的污染问题，难以清洗此外，由于水和油在渗透时都在膜表面润湿，它们不能有效分离不含表面活性剂的分散油水混合物或水包油乳液。由于油和水的不同界面效应，利用固体表面的润湿行为来设计油水分离过程被认为是有效的。通过设计超疏水或超疏油表面，结合表面化学和表面粗糙度，制备了一系列超湿材料Jiang等人首次报道了一种具有超疏水性和超亲油性的聚四氟乙烯（PTFE）涂层网膜，用于油和水的分离从那时起，超疏水材料被广泛研究并用于去除水中的油由于水的密度通常比油高，它往往会形成一个屏障层来防止油的渗透。此外，这些材料容易被粘附或吸附的油污染，从而导致通量和分离效率迅速下降，并造成二次污染。因此，超疏水材料不适用于富水油水混合物或水包油乳液的分离。从实际应用的角度来看，开发超疏油/超亲水表面可能为油水分离提供一种可行的替代方法。然而，由于水的表面张力高于油，根据杨氏方程，疏油表面也是疏水的此外，由于大多数固体的高表面能性质，超疏油材料的制造相当稀少，并且很少有关于其用于油水分离的报道。实现超疏油的最有效方法是在微/纳米级结构上引入氟化低表面能化学物质Tuteja最近取得了一项突破，他展示了一种氟癸基POSS+ x-PEGDA（多面体低聚硅氧烷+ x-聚乙二醇二丙烯酸酯）共混涂层的水响应网状膜，该膜在空气和水下都是超亲水和超疏油的。该膜可用于分离粒径大于1 μm.[10]的油水乳液除了氟化化学品对环境的影响问题外，氟化超疏油表面只能在空气中稳定，接触水一般会剥夺其超疏油性能，导致疏油功能丧失近年来，利用具有亲水特性的高能材料在油/水/固三相体系中构建水下超疏油表面的新概念被提出。
Oil/water separation has been a worldwide subject because of increasing release of industrial oily wastewater as well as frequent crude oil leakage.[1] Traditional techniques for oil/water separation such as air flotation, gravity separation combined with skimming, oil-absorbing materials, coagulation, and flocculation are limited by low separation efficiency, energy-cost, and complex separation instruments, etc. and are not effective for separating tiny oil droplets from water, making further treatment necessary.[2] Polymer-oriented filtration membranes such as for ultrafiltration (UF) have been successfully applied for the separation of surfactant-stabilized oil-in-water emulsions driven by external pressure.[3] But the most serious limitation of filtration membranes is the low flux and quick decline of permeation due to oil adsorption and/or pore plugging by oil droplets, which lead to severe fouling issues and are hard to clean.[4] In addition, they are not effective to separate surfactant-free dispersed oil/water mixtures or oil-in-water emulsions due to both water and oil wetting on the membrane surface when permeating. Owing to the different interfacial effects of oil and water, utilizing the wetting behavior of solid surfaces to design an oil/water separation process has been considered effective. A series of superwetting materials have been fabricated by designing superhydrophobic or superoleophobic surfaces in combination with surface chemistry and roughness.[5] Jiang et al. first reported a teflon (PTFE) coated mesh film with superhydrophobicity and superoleophilicity for separation of oil and water.[6] Since then superhydrophobic materials have been extensively investigated and used to remove oils from water.[7] As water usually has a higher density than oils, it tends to form a barrier layer to prevent oil permeation. In addition, these materials are easily fouled by adhered or adsorbed oils thus result in the quick decrease of flux and separation efficiency, as well as secondary pollution. Therefore, superhydrophobic materials are unsuitable for the separation of water-rich oil/water mixtures or oil-in-water emulsions. From a practical point of view, developing superoleophobic/superhydrophilic surfaces may provide an alternative and feasible way for oil/water separation. However, due to the higher surface tension of water than oil, the oleophobic surfaces are also hydrophobic according to Young's equation.[8] Moreover, the fabrication of superoleophobic materials is rather sparse due to the high-surface-energy nature of most solids and significantly few reports appear on their application for oil/water separation. The most effective way to achieve superoleophobicity is by introducing fluorinated lowsurface-energy chemicals on micro/nano-hierarchical structures.[9] A breakthrough was recently achieved by Tuteja who demonstrated a fluorodecyl POSS+ x-PEGDA (polyhedral oligometric silsesquioxiane+ x-poly (ethylene glycol) diacrylate) blend-coated hygro-responsive mesh membrane which is both superhydrophlic and superoleophobic in air and under water. This membrane is valuable for separation of an oil/water emulsion with a droplet size larger than 1 μm.[10] Besides the issue of the effect of fluorinated chemicals on the environment, the fluorinated superoleophobic surfaces can only stabilize in air, the superoleophobic property of which would be generally deprived when touching water and lead to the loss of oil repellency function.[11] Recently, a new concept of taking advantage of high-energy materials with water-favoring property to construct underwater superoleophobic surfaces in oil/water/solid three-phase systems is proposed, which is inspired by the …