Chelator auxiliary electrodialysis (CAED) for efficient and sustainable lithium extraction and magnesium co-recovery from salt lake brines

The demand for lithium (Li) has been increasing due to the rapid expansion of the lithium-ion battery market. Lithium extraction from salt-lake brine has proven to be both sustainable and economical. Electrodialysis is an emerging green process for recovering valuable metals from salt-lake brine with complex compositions. However, substantial challenges remain, particularly regarding the poor selectivity against magnesium, a major competing species, which limits the efficiency of the extraction processes. This study focuses on the separation and recovery of lithium and magnesium from low Li⁺/Mg²⁺ ratio brine via chelator auxiliary electrodialysis process (CAED), enabling direct lithium extraction and efficient magnesium by-product recovery. By leveraging the selective binding between Mg²⁺ and [EDTA]⁴⁻, our process achieves a lithium recovery rate exceeding 97.64 %, with an exceptionally high magnesium retention of 85 % and an unprecedented Li⁺/Mg²⁺ separation factor (SF) of 592.96 under constant current conditions (20 mA/cm²). Furthermore, through the utilization of endogenously generated base from electrode reaction, over 85 % of Mg²⁺ is converted to Mg(OH)₂, while more than 90 % of [EDTA]⁴⁻ is regenerated. The scalable nature of this process ensures efficient lithium resource recovery with minimal reagent loss, minimizing environmental impact while maximizing resource utilization. This work contributes to the advancement of sustainable lithium extraction technologies, supporting the global transition toward cleaner energy solutions.