Preparation of anion exchange membrane by efficient functionalization of polysulfone for electrodialysis

In this study, a chloromethylated polysulfone with controlled degree of chloromethylation (DCM) was synthesized for the preparation of anion exchange membranes (AEMs). The reported method avoided using the hazardous chemicals chloromethyl ether but achieved the same high DCM (up to 1.95) under mild experimental conditions. Various process parameters, including reaction time and temperature, solvent type and volume, and catalyst feeding mode and volume, were discussed to demonstrate how a relatively high DCM could be achieved through this process. AEMs with varied DCM were prepared and their performances were characterized. The reported AEM-1.95 possessed better properties as a result of the high molality of chloromethyl groups, such as higher ion exchange capacity and ionic conductivity, better thermal stability and alkaline stability, as well as better mechanical properties. Additionally, electrodialysis (ED) experiments were conducted to determine the feasibility of AEMs in practical applications. Results showed that the AEM prepared by higher DCM exhibited better desalination properties and lower energy consumption. The desalination rate of AEM-1.95 could be up to 94.5% and the energy consumption was only 7.5 kWh/kg. All the results demonstrate that the proposed route for efficient and non-toxic fabrication of CMPSF with high DCM exhibits significantly potential and may be a promising candidate for the preparation of AEMs with high performances.