Shi Yongxuan, Zheng Qifeng, Ding Liujie, Yang Fenglin, Jin Wenbiao, Tang Chuyang Y, Dong Yingchao
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China.
Environ Sci Technol. 2022 Apr 5;56(7):4518-4530. doi: 10.1021/acs.est.2c00336. Epub 2022 Mar 8.
Conventional separation membranes suffer from evitable fouling and flux decrease for water treatment applications. Herein, a novel protocol of electro-enhanced membrane separation is proposed for the efficient treatment of microsized emulsions (∼1 μm) by rationally designing robust electroresponsive copper metallic membranes, which could mitigate oil fouling and coenhance permeance (from ∼1026 to ∼2516 L·m·h·bar) and rejection (from ∼87 to ∼98%). High-flux Cu membranes exhibit superior ductility and electrical conductivity, enabling promising electroactivity. Separation performance and the fouling mechanism were studied under different electrical potentials and ionic strengths. Application of negative polarization into a large-pore (∼2.1 μm) Cu membrane is favorable to not only almost completely reject smaller-sized oil droplets (∼1 μm) but also achieve antifouling and anticorrosion functions. Moreover, surfactants around oil droplets might be redistributed due to electrostatic repulsion, which effectively enhances the steric hindrance effect between neighboring oil droplets, mitigating oil coalescence and consequently membrane fouling. Furthermore, due to the screening effect of surfactants, the presence of low-concentration salts increases the adsorption of surfactants at the oil-water interface, thus preventing oil coalescence via decreasing oil-water interfacial tension. However, under high ionic strengths, the fouling mechanism converts from cake filtration to a complete blocking model due to the reduced electrostatic repulsion between the Cu membrane and oil droplets. This work would provide mechanistic insights into electro-enhanced antifouling for not only oil emulsion separation but also more water treatment applications using rationally designed novel electroresponsive membranes.
传统的分离膜在水处理应用中存在不可避免的污染和通量下降问题。在此，通过合理设计坚固的电响应性铜金属膜，提出了一种用于高效处理微米级乳液（约1μm）的电增强膜分离新方案，该方案可以减轻油污并同时提高渗透率（从约1026提高到约2516 L·m·h·bar）和截留率（从约87%提高到约98%）。高通量铜膜具有优异的延展性和导电性，具有良好的电活性。研究了在不同电势和离子强度下的分离性能和污染机理。对大孔（约2.1μm）铜膜施加负极化不仅有利于几乎完全截留较小尺寸的油滴（约1μm），还能实现防污和防腐功能。此外，油滴周围的表面活性剂可能会因静电排斥而重新分布，这有效地增强了相邻油滴之间的空间位阻效应，减轻了油的聚结，从而减轻了膜污染。此外，由于表面活性剂的屏蔽作用，低浓度盐的存在增加了表面活性剂在油水界面的吸附，从而通过降低油水界面张力来防止油的聚结。然而，在高离子强度下，由于铜膜与油滴之间的静电排斥减弱，污染机理从滤饼过滤转变为完全堵塞模型。这项工作不仅将为油乳液分离，而且为使用合理设计的新型电响应膜的更多水处理应用提供电增强防污的机理见解。
