A facile approach to fabricate composite anion exchange membranes with enhanced ionic conductivity and dimensional stability for electrodialysis

摘要

It is significant to develop anion exchange membranes (AEMs) with efficient ionic transport and desirable stabilities (mechanical and dimensional) for various applications, including electrodialysis (ED). In this paper, three types of composite AEMs based on quaternized polysulfone (QPSU) and polyvinyl alcohol (PVA) blends: QPSU/PVA composite AEM (M-0), potassium thioacetate (PT) modified QPSU blending with PVA (M-1) and QPSU blending with 4-formylbenzoic acid (FBA) modified PVA (M-2-X, X = mass ratio of the FBA with the values of 0.05 and 0.20), have been investigated. Our investigation demonstrates that the swelling ratios of M-1 and Mr 0.05 were significantly reduced to 10.9% and 4.7% at 20 degrees C, much lower than Mo (16.9%). This can be due to the formed hydrogen-bonding network via -OH from PVA and > C=O from PT structure on PSU within M-1 or the ionic crosslinking interactions between -COO- from FBA and > N+-on QPSU within M-2. Though the free volume inside AEM matrix is reduced, the chloride ion conductivities of M-1 and M-2-0.05 reach 20.5 mS cm(-1) and 23.5 mS cm(-1) at 20 degrees C. In ED application, the optimized M-2-0.05 has the highest NaCI removal ratio of 74.6% within 120 min (vs. 61.06% of the commercial AEM-Type II), and exhibits better desalination performance with high current efficiency (98.0% vs.92.8%) and lower energy consumption (2.2 kWh kg(-1) NaCl vs. 2.4 kWh kg(-1)). The simple preparation process and good ED performance of M-2-0.05 are indicative of its potential ED application.