Acid enrichment via electrodialyser fabricated with poly(vinyl chloride)-based anion exchange membrane: Effect of hydrophobicity of aliphatic side-chains tethered on imidazolium groups

Electrodialysis (ED) technology equipped with proton blocking anion exchange membranes (AEMs) has great potential applications in recovering acidic wastewater. To develop high performance proton-blocking AEMs, in this work, a series of imidazolium functionalized poly(vinyl chloride) (PVC) AEMs are designed. In particular, the length of alkyl side chains tethered on the imidazole compound is optimized to adjust the micro-structure of AEM. Our research demonstrates that the density of 1-butylimidazole functionalized PVC AEM matrix is enhanced, which has been proved by water uptake and thermogravimetric analysis . Hence, the acid blocking performance of optimized AEM (PVC-Im-4C) is strengthened. The maximum concentration of H + in concentrate chamber of electrodialyser enriched by the PVC-Im-4C AEM is 1.81 M through the 24 h ED process at a current density of 20 mA·cm −2 (the initial concentration of hydrogen ions: 1.0 M). The result suggests that the optimized PVC-Im-4C AEM with long alkyl side chain on imidazole shows the excellent capacity in acid enrichment. This work should provide guidance for the follow-up design of the advanced proton blocking AEMs.