Poly(arylpiperidine) anion-exchange membranes utilizing varied side-chain cross-linking for enhanced electrodialytic ion separation in alkaline waste treatment

Abstract

Electrodialysis with anion-exchange membranes (AEMs) is effective for reclaiming alkaline substances from industrial effluents, but conventional AEMs suffer from active group degradation under harsh alkaline conditions. To address this limitation, we designed novel polyarylpiperidine-based AEMs using 1,6-dibromohexane as the cross-linker and incorporating varied side-chain groups. The optimized PBP-co-COOH AEM exhibited exceptional alkali stability: nuclear magnetic resonance confirmed polymeric backbone stability after 1200 ​h of exposure to 2.0 ​M NaOH at 80 ​°C, and thermogravimetric analysis showed minimal mass loss (<8.7 ​%). In practical electrodialysis (feed concentration: 0.40 ​M–0.11 ​M), this membrane achieved a high current efficiency of 90.21 ​% and low energy consumption of 2.22 ​kW ​h ​kg⁻¹, outperforming the commercial Neosepta AHA membrane (80.31 ​% current efficiency, 2.75 ​kW ​h ​kg⁻¹ energy consumption) in both metrics. These results demonstrate that modulating ionic moieties in membrane side chains significantly enhances electrodialysis performance. This membrane design provides a promising strategy for developing alkali-resistant AEMs, with valuable implications for optimizing alkaline reclamation processes and advancing industrial-scale applications.