Bifunctional Crosslinker Enables Antifouling PVA-Based Anion Exchange Membranes with Enhanced Dimensional Stability for Electrodialysis Applications

Membrane fouling is a challenging problem that negatively affects the membrane performance. To suppress the fouling, in this work, a series of bipyridine-containing crosslinked anion exchange membranes (AEMs) (denoted as PVA-Bpy-CHO-X) have been prepared, where poly­(vinyl alcohol) (PVA) is the membrane substrate and Bpy-CHO with a rigid structure is the crosslinker. The optimized PVA-Bpy-CHO-0.40 possesses an appropriate swelling ratio (11.3%), low surface area resistance (3.21 Ω·cm2), and enhanced hydrophilicity (water contact angle: 76.4°). Especially, PVA-Bpy-CHO-0.40 also exhibits a superior NaCl removal ratio of 85.16 ± 0.9% within 210 min, which is higher than that of commercial AEM-Type-II (84.46 ± 0.8%). As for the antifouling performance of AEMs, the electrodialysis (ED) stack was fed with a solution containing 0.05 M NaCl (aq.) and contaminant model of 0.8 g·L–1 SDBS. The antifouling potential is evaluated by transition time, which is defined as the time that passes when voltage across the membrane (ΔE) presents a sharp rise for the increased surface area resistance when the fouling occurs. As a result, PVA-Bpy-CHO-0.40 shows a longer transition time of 750 min relative to AEM-Type-II (620 min), suggesting its superior antifouling performance and the potential to be a good candidate for ED in organic foulant systems.