Efficient lithium extraction by membrane capacitive deionization incorporated with monovalent selective cation exchange membrane

Membrane capacitive deionization (MCDI) is an effective water purification technology. In this work, a monovalent selective cation exchange membrane (CIMS) was assembled in MCDI system (denoted as MSCDI) to separate lithium from magnesium. The effects of feed water quality and operating conditions on the lithium removal selectivity were systematically investigated. Specifically, in optimized conditions, the lithium selectivity coefficient reached 2.95. Furthermore, a custom-made large MSCDI module was applied to the selective removal of lithium. The removal rates of Li+ and Mg2+ in large module reached 38.4% and 19.2%, respectively. It is worth noting that the specific energy consumption was 0.0018 kWh mol−1, which is much lower than that of electrodialysis (0.04-0.27 kWh mol−1). Therefore, relying on its low energy consumption and environmental friendliness, MSCDI has considerable economic benefits for the efficient lithium extraction.