Using γ‐Valerolactone as a Nontoxic Solvent for Fabricating Anion‐Exchange Membrane via Nonsolvent‐Induced Phase Separation

ABSTRACT The nonsolvent induced phase separation (NIPS) method and its variants have garnered significant attention for the fabrication of ion‐exchange membranes (IEMs) due to several potential advantages, including ease of scalability, reduced material requirements, and enhancements in operational performance. However, the hazards associated with traditional membrane fabrication solvents poses a considerable limitation to the advancement and application of NIPS. This study explores the use of a green solvent, specifically γ‐valerolactone (GVL), for the first time in the preparation of IEMs via the NIPS technique. Initially, fundamental investigations, including thermodynamic and kinetic analyses of the casting solution composed of GVL and chloromethylated polysulfone (CMPS), as well as assessments of membrane morphology and electrochemical properties, are conducted to evaluate the feasibility of IEM production in comparison to the NMP/CMPS system. Additionally, some applied experiments, such as desalination by electrodialysis (ED) and acid recovery via diffusion dialysis (DD), are performed to examine the impacts of casting solution composition on the performances of the resulting membranes. The results from the ED experiments indicate that the membrane produced from a 19 w.% GVL/CMPS solution can achieve a 27% reduction in energy consumption while maintaining a comparable current efficiency to commercial membranes. Furthermore, the DD experiments reveal that this membrane exhibits a H + dialysis coefficient of m/h and a separation factor of 256, significantly surpassing the performance metrics of commercial membranes. These findings clearly demonstrate that GVL is a viable green solvent for the preparation of polysulfone IEMs with highly competitive performance characteristics.