Design and Application of Redox-Mediated Flow Electrode Electrodialysis for Ion Removal and Recovery

To meet the growing demand for freshwater driven by population growth and rising living standards, the first desalination plants were established in the late 1950s. As energy costs have risen over time, research has increasingly focused on reducing the overall cost of water treatment. Electrodialysis (ED), which facilitates the migration of anions and cations across ion exchange membranes under the influence of an electric field, has gained significant attention as a treatment method for saline water and brine due to its simplicity, low cost, and scalability. However, its traditional batch operation mode and the potential for generating flammable gases have limited its development, highlighting the need for improvements. Also, in recent years, as global populations and economies have grown rapidly, alongside advancements in science and technology, the demand for critical materials has surged. This has created a pressing need for new extraction and separation technologies. ED, whose versatility has long been underappreciated, is now receiving increased attention for applications beyond its conventional uses. In this work, we present the design of a redox-mediated flow electrode electrodialysis (RED) system and its initial application in desalination. This system enables fast, energy-efficient, green energy-compatible, and, most importantly, continuous desalination across various water sources, paving the way for industrial-scale applications. Additionally, we explore its broader potential, including research on the adsorption and release of different ions in the LSTH selective membrane, enabling the RED system to directly extract vi lithium from brines. High-purity lithium is successfully recovered from various brine sources, including seawater, through this selective membrane. Moreover, we have investigated the subtle differences in the diffusion coefficients and bond energies of isotopes, demonstrating the RED system's capability for isotope separation, effectively achieving lithium isotope enrichment with a high separation factor.