Scale-Up Strategies for Redox-Mediated Electrodialysis for Desalination: The Role of Electrode and Channel Stacks.

Abstract

Redox-mediated electrodialysis (redox-ED) enhances the economic and energy feasibility of conventional electrodialysis by substituting water splitting and costly metal-basedelectrodes with reversible redox reactions and porous carbon electrodes. Despite growing interest, the development of scale-up strategies for redox-ED remains limited, delaying its industrial implementation. This study proposes a scale-up strategy by examining the impact of stacking electrodes and channels on the desalination performance of the system, aiming to enable economically viable desalination. The results show that electrode and channel stacking (up to three stacks) significantly enhances desalination performance, resulting in a 6.8-fold increase in the salt removal rate, and a 30% improvement in productivity. These enhancements can be attributed to synergistic effects of electrode and channel stacking, which improve the redox reaction rate by increasing the surface area and enhancing the system capacity by increasing the volumetric flow rate. Technoeconomic analysis underscores the economic viability of the scale-up strategy proposed in this study, showing 18% and 32% reductions in capital and operating costs, respectively, compared with multiple unit cell systems. Overall, incorporating multiple stacks of electrodes and channels offers an effective strategy for scaling up redox-ED systems with high economic viability, thereby providing a pathway for their industrial utilization.