Advancing Lithium Recovery: Evaluation of Electrodialysis, Capacitive Deionization, and a Hybrid Electrochemical System

Because of the increasing demand for lithium, interest has grown in developing highly efficient methods to separate lithium from non-conventional sources such as lithium clays. This study assesses electrodialysis (EDU) and capacitive deionization (CDI), as well as a combined EDU–CDI method, for recovering and purifying lithium from a chloride-containing leachate solution obtained from lithium clays. This study examined the initial stage of the EDU process. Under different conditions (voltage, treatment time, and flow rates), the concentration depletion and enrichment of lithium, as well as its recovery and selectivity, were investigated. All electrochemical experiments were conducted at ambient laboratory temperature. CDI was examined as a polishing technique, with particular attention to lithium recovery and discrimination between Li+ and Na+ ions using modified carbon-based electrodes. The results show that the EDU technique can promote lithium transport and enrichment; however, Li/Na selectivity remains low because the monovalent ions are transported simultaneously. The CDI technique has demonstrated a greater degree of lithium enrichment compared to that of Na+ ions, which shows its potential as a selective separation step. When combined, the techniques show complementary effects: EDU performs bulk ion separation, while CDI improves the quality of the lithium-enriched solution. Furthermore, preliminary tests have indicated promising behavior of the LiMn2O4-based electrodes.