Separation of organic liquid mixture by flexible nanofibrous membranes with precisely tunable wettability

Abstract

Separation of liquid mixtures, especially organic liquid mixtures, is widely used in industrial processes but still faces challenges with respect to separation in a high-efficiency, low-energy mode. In this work, we report a flexible wettability-tunable nanofibrous membrane composed of a high-performance fluoro-polymer as the matrix and fluorosilane as a surface energy regulator that can be successfully applied in immiscible organic liquid mixture separation. The separation is achieved by tuning the surface energy of a membrane to a value between the surface tensions of two organic liquids. Moreover, for use in different mixed liquid systems, we programmatically designed nanofibrous membranes with the proper surface energy that could intercept the relatively high surface tension liquid and allow the low surface tension liquid to pass through. These membranes are expected to become a competitive candidate for complex organic chemical product separation, resource recycling, and environmental protection. Polymer nanofibre membranes with tunable wetting properties can match the surface tension of complex liquids and separate them. Purifying organic liquids with similar physical properties often requires energy-intensive methods. However, a membrane developed by Yong Zhao from Beihang University in China and colleagues offers high-throughput separation, thanks to incorporate of ‘dopants’ made from long silicon fluorocarbon chains, which repel both water and oil, into electrospun nanofibres made from poly(vinylidene fluoride-co-hexafluoropropylene enabled the team to selectively adjust membrane wetting to match organic liquid targets. With organic liquids having slightly different surface tensions, such as propylene glycol and benzene solutions, the membranes intercepted the high-surface tension liquid while the other passed through spontaneously. The flexible membrane offers improved mechanical properties over conventional ceramic membranes and is promising for cleaning oil spills and treating other environmental problems. Organic liquid separation is currently an important but troublesome issue, which closely related to resource recycling and environmental protection. Here we reported a wettability-tunable nanofibrous membrane that can be used for efficient separation of wide ranges of immiscible organic liquid mixtures.