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.