Institute of Process Engineering, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria.
Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06520-8286, USA; Rohsenow Kendall Heat Transfer Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge MA 02139-4307, USA.
Water Res. 2018 Aug 1;139:329-352. doi: 10.1016/j.watres.2018.03.058. Epub 2018 Mar 30.
Membrane distillation (MD) is a rapidly emerging water treatment technology; however, membrane pore wetting is a primary barrier to widespread industrial use of MD. The primary causes of membrane wetting are exceedance of liquid entry pressure and membrane fouling. Developments in membrane design and the use of pretreatment have provided significant advancement toward wetting prevention in membrane distillation, but further progress is needed. In this study, a broad review is carried out on wetting incidence in membrane distillation processes. Based on this perspective, the study describes the wetting mechanisms, wetting causes, and wetting detection methods, as well as hydrophobicity measurements of MD membranes. This review discusses current understanding and areas for future investigation on the influence of operating conditions, MD configuration, and membrane non-wettability characteristics on wetting phenomena. Additionally, the review highlights mathematical wetting models and several approaches to wetting control, such as membrane fabrication and modification, as well as techniques for membrane restoration in MD. The literature shows that inorganic scaling and organic fouling are the main causes of membrane wetting. The regeneration of wetting MD membranes is found to be challenging and the obtained results are usually not favorable. Several pretreatment processes are found to inhibit membrane wetting by removing the wetting agents from the feed solution. Various advanced membrane designs are considered to bring membrane surface non-wettability to the states of superhydrophobicity and superomniphobicity; however, these methods commonly demand complex fabrication processes or high-specialized equipment. Recharging air in the feed to maintain protective air layers on the membrane surface has proven to be very effective to prevent wetting, but such techniques are immature and in need of significant research on design, optimization, and pilot-scale studies.
膜蒸馏（MD）是一种快速发展的水处理技术；然而，膜孔润湿是 MD 广泛应用于工业的主要障碍。膜润湿的主要原因是液体入口压力超过和膜污染。膜设计的发展和预处理的使用为膜蒸馏中的防润湿提供了重大进展，但仍需要进一步的进展。本研究对膜蒸馏过程中的润湿发生率进行了广泛的综述。基于这一观点，本文描述了膜润湿的机制、原因和检测方法，以及 MD 膜的疏水性测量。本综述讨论了目前对操作条件、MD 配置和膜非润湿性特征对润湿现象的影响的理解和未来研究领域。此外，还强调了数学润湿模型和几种润湿控制方法，如膜制造和改性，以及 MD 中膜修复技术。文献表明，无机结垢和有机污染是膜润湿的主要原因。发现润湿 MD 膜的再生具有挑战性，得到的结果通常不理想。几种预处理工艺被发现可以通过从进料溶液中去除润湿剂来抑制膜润湿。各种先进的膜设计被认为可以使膜表面达到超疏水性和超双疏水性的非润湿性状态；然而，这些方法通常需要复杂的制造工艺或高专业化的设备。向进料中注入空气以在膜表面上保持保护性空气层已被证明是非常有效的防止润湿的方法，但这些技术还不成熟，需要在设计、优化和中试研究方面进行大量研究。
