
膜接触破乳——用于油包水乳液分离的超疏水ZIF-8@rGO膜
Jiahui Gu, Zhou Qu, Xiangning Zhang, Hongwei Fan, Chunxi Li, Jürgen Caro, Hong Meng
工程(英文) ›› 2023, Vol. 23 ›› Issue (4) : 73-81.
膜接触破乳——用于油包水乳液分离的超疏水ZIF-8@rGO膜
Membrane Contact Demulsification: A Superhydrophobic ZIF-8@rGO Membrane for Water-in-Oil Emulsion Separation
水-油界面不平衡是实现油包水乳液破乳的关键。传统膜通常是依赖较高的跨膜压力破坏界面平衡而实现破乳。本文提出了可自然、快速地破坏水-油界面平衡的“接触破乳”的概念,开发了一种对有机组分具有高通量的新型破乳分离膜。具体制备过程分为两步,首先通过真空辅助抽滤法在聚四氟乙烯(PTFE)基底上组装ZIF-8@rGO微球(ZGS)层,再采用聚二甲基硅氧烷(PDMS)交联溶液进行固定化处理。由于ZGS表面为微纳米阶层结构,所制备的ZIF-8@rGO@PDMS/PTFE(ZGPP)膜表面展现出超疏水性特性,当表面活性剂稳定的油包水乳液接触到膜表面时,微纳结构的超疏水膜表面会引起水-油界面不平衡。ZGPP膜对油包水乳液具有良好的分离破乳性能,在0.15 bar(15 kPa)的低跨膜压力下,分离效率可以达到99.57%,通量可达到2254 L·m‒2·h‒1,且对于表面活性剂稳定的纳米级甲苯水乳液(平均液滴尺寸为57 nm)的体系也可以实现破乳分离。“接触破乳”概念的提出有望为开发新一代油包水乳液分离的破乳膜提供新的思路。
Achieving a water–oil interface imbalance has been identified as a critical factor in the demulsification of water-in-oil emulsions. However, conventional demulsifying membranes generally break the interface balance by depending on a relatively high transmembrane pressure. Here, we present a ″contact demulsification″ concept to naturally and quickly achieve disruption of the water–oil interface balance. For this purpose, a novel demulsifying membrane with a high flux of the organic component has been developed via the simple vacuum assembly of zeolitic imidazolate framework-8 (ZIF-8)@reduced graphene oxide (rGO) microspheres (ZGS) on a polytetrafluoroethylene (PTFE) support, followed by immobilization processing in a polydimethylsiloxane (PDMS) crosslinking solution. Due to the micro-nano hierarchies of the ZGS, the prepared ZIF-8@rGO@PDMS/PTFE (ZGPP) membranes feature a unique superhydrophobic surface, which results in a water–oil interface imbalance when a surfactant-stabilized water-in-oil emulsion comes into contact with the membrane surface. Under a low transmembrane pressure of 0.15 bar (15 kPa), such membranes show an excellent separation efficiency (~99.57%) and a high flux of 2254 L·m–2·h–1, even for surfactant-stabilized nanoscale water-in-toluene emulsions (with an average droplet size of 57 nm). This ″contact demulsification″ concept paves the way for developing next-generation demulsifying membranes for water-in-oil emulsion separation.
Water-in-oil emulsion / Demulsification / Oil/water separation / Superhydrophobic membrane
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