Optimizing Operational Parameters for Lithium Hydroxide Production via Bipolar Membrane Electrodialysis

Traditional lithium hydroxide production techniques, like lithium sulfate and lithium carbonate causticizing methods, suffer from drawbacks including high specific energy consumption, time-consuming processes, and low recovery rates. The conversion of lithium chloride to lithium hydroxide using bipolar membrane electrodialysis is straightforward; however, the influence of operational parameters on bipolar membrane electrodialysis performance have not been investigated. Herein, the impact of the current density (20 mA/cm2~80 mA/cm2), feed concentration (0.5 M~2.5 M), initial feed pH (2.5, 3.5 and 4.5), and the volume ratio of the feed and base solution (1:1, 2:1 and 3:1) on the current efficiency and specific energy consumption in the bipolar membrane electrodialysis was systematically investigated. The bipolar membrane electrodialysis process showed promising results under optimal conditions with a current density of 50 mA/cm2 and an initial lithium chloride concentration of 1.5 M. This process achieved a current efficiency of 75.86% with a specific energy consumption of 3.65 kwh/kg lithium hydroxide while also demonstrating a lithium hydroxide recovery rate exceeding 90% with a purity of about 95%. This work will provide valuable guidance for hands on implementation of bipolar membrane electrodialysis technology in the production of LiOH.