Emerging membranes for separation of organic solvent mixtures by pervaporation or vapor permeation

Separation of organic-organic solvent mixtures is energy-intensive by using conventional methods, which is also a challenging task for membrane technology. Over the past decade, pervaporation (PV) and vapor permeation (VP) have been continuously studied for the separation of organic solvent mixtures. The PV and VP processes are limited by thermodynamic vapor–liquid equilibrium (VLE) and thus consume less energy compared with conventional distillation technology. In this review, we focus on the membrane materials toward organic solvent PV/VP separation, including polymeric membranes, microporous membranes, mixed-matrix membranes and other emerging membranes, and separation systems in the recent decade, and define the current state-of-the-art for membrane materials and performance. The separation mechanism of different membrane materials such as affinity and size sieving, or the synergy of both is discussed, aiming to understand the priority permeation orders in different types of membrane materials, and provide fundamental insights for the design of high-performance membrane materials and structures. Additionally, the PV/VP process is compared with reverse osmosis (RO) process toward organic solvent separation in terms of membrane materials, separation performance and transport mechanism. Finally, we outlook the potential opportunities and challenges of applying advanced membrane materials for PV/VP separation of organic solvent mixtures.