Highly selective lithium recovery from high Mg/Li ratio brines

Here, we report a new liquid-membrane electrodialysis capable of selectively recovering lithium from high Mg/Li ratio brines. The liquid membrane is composed of an ionic liquid system as the Li+ carrier that presents high selectivity toward Li+ and long-term sustainability, and 2 solid cation-exchange membranes to sandwich the carrier. Recognition and selective electromigration of Li+ can be achieved by the sandwiched liquid membrane assisted by an electric field. The Mg/Li decreases from 50:1 in the initial feeding brine to 0.5:1 in the receiving solution after electrodialysis at a current density of 4.375 A·m−2 for 12 h. Moreover, higher current efficiency (65%) and lower specific energy consumption (16 Wh·g−1 Li) are obtained compared to typical electrodialysis processes. From the perspective of practical application, the Mg/Li drops to 0.26:1 from 53:1 in the old brine from West Taijinair, and K+ and Ca2+ in the brine are almost completely blocked by the liquid membrane. This method displays a great perspective on the application for lithium recovery from high Mg/Li brines owing to its high selectivity, efficient energy utilization, and environmental friendliness.