Chlorine-Induced Membrane Degradation in Bipolar Membrane Electrodialysis: Mechanisms, Performance Impacts, and Mitigation Strategies

Abstract Bipolar membrane electrodialysis (BMED) has emerged as a promising electrochemical process for producing acids, bases, and value-added chemicals from saline solutions, while also offering pathways for carbon dioxide removal through ocean alkalinity enhancement. However, despite recent advances in energy efficiency and process design, most studies have focused on short-term performance, leaving critical gaps in understanding the durability of BMED systems under continuous or repeated operation. In this work, we investigate the stability of BMED membranes and process performance over an extended testing period totaling more than 1 month and under accelerated aging conditions, using sodium chloride solutions as feedwater. We systematically evaluate the impact of operating conditions and electrode rinse solution (ERS) concentration on chlorine generation, membrane degradation, and overall performance. Our findings quantify the degree to which higher ERS concentrations delay the onset of chlorine formation, mitigating one of the key causes of anion-exchange membrane failure and significantly extending stable operation. Moreover, we show how chlorine species produced during operation impact membrane integrity, progressively reducing performance. This study represents one of the first systematic durability evaluations of BMED over multicycle operation, directly addressing the scalability challenges of BMED. The results not only clarify fundamental performance–stability trade-offs but also provide a practical foundation for industrial application of BMED in areas such as brine valorization and large-scale carbon removal technologies.