A two-step strategy for the preparation of anion-exchange membranes based on poly(vinylidenefluoride-co-hexafluoropropylene) for electrodialysis desalination

Abstract

The development of a facile approach to fabricate anion exchange membranes (AEMs) with efficient ionic transport and desirable stabilities (mechanical and dimensional) for various applications is meaningful. In this work, a two-step strategy for the preparation of AEMs with 3D network structure, via cross-linking reaction between 2-chloroacetamide (CAA) modified poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and N,N,N′,N′-tetramethyl-1,4-diaminobutane (TMDAB) has been reported. The as-prepared AEMs with ion-exchange capacity (IEC) in the range of 1.38–1.84 mmol g−1, exhibit the much lower water uptake (13.14–22.45%, 80 °C) relative to the un-crosslinked AEM (35.89%, 80 °C). In addition, due to the presence of fluorine-based 3D network structure, the as-prepared AEMs show much enhanced mechanical and thermal stability in comparison with the un-crosslinked AEM. In the electrodialysis (ED) application, the optimized AEM shows the higher current efficiency (78.6%) and lower energy consumption (2.01 kWh kg−1 NaCl) than those of commercial AEM AEM-Type II (76.4%; 2.26 kWh kg−1), respectively, within 150 min of operation interval. The proposed facile fabrication protocol and the better-performance of optimized PVDF-HFP -based AEM demonstrate the potential ED application.