Electro-deionization (EDI) technology for enhanced water treatment and desalination: A review

Extensive industrialization, agricultural development, and continued population growth have triggered economic and physical water scarcity. Advanced water treatment and desalination technologies with high ion removal capacity and energy efficiency are highly desirable to mitigate water pollution and shortage. Electrochemical separation techniques have exciting features such as chemical selectivity, versatility, compact size, decreased generation of secondary waste, and broad applicability in ion separation and water purification. Electrodeionization (EDI), which combines the synergistic properties of ion exchange resins (ion exchange, IX) and ion-selective membranes (Electrodialysis, ED), is one such promising electrochemical process. Herein, we briefly introduce the fundamentals of the EDI process, including its configuration, working principle, ion removal mechanism, and critical evaluation metrics for EDI performance. Various advantages and drawbacks of EDI are also discussed, along with scientific strategies to mitigate the bottleneck and improve the process. Furthermore, novel tailored applications are specifically addressed, including heavy metal ion removal, water desalination, and low-level radioactive waste removal. On top of that, the review also compares EDI with other conventional techniques regarding removal efficiency, energy consumption, and resin regeneration. Lastly, the current global market, remaining challenges, and potential research directions are summarized to offer strategies for future development in this promising field.