Lithium recovery from artificial brine using energy-efficient membrane distillation and nanofiltration

Herein, we introduce a novel membrane-based process for lithium recovery and compare it to the conventional solar evaporation followed by chemical precipitation process. Conventional technologies have limitations to meet the recent demand for massive lithium production due to several drawbacks of solar evaporation. Recently, in order to reduce the dependency of solar evaporation, several technologies have been proposed such as precipitation, ion-exchange, liquid-liquid extraction, adsorption, and electrodialysis. We suggest a novel membrane-based lithium recovery process by combining membrane distillation (MD) and nanofiltration (NF) to concentrate a brine solution containing lithium and to remove divalent ions. The proposed membrane-based process was demonstrated to concentrate 100 ppm lithium solution in artificial brine to 1200 ppm lithium solution within several days and exhibited up to 60 times higher water flux (22.5 L m−2 h−1) than that of solar evaporation (0.37 L m−2 h−1 at 30 °C and 0.56 L m−2 h−1 at 50 °C). Moreover, the NF process can suppress crystal formation to prevent process failure while alleviating the massive chemical usage of the conventional process. As a result, the proposed membrane-based process showed a possibility to utilize the low concentration of lithium brine with one-tenth of capital cost, process time, and foot-print of the conventional process, and represented a competitive operating cost with the conventional process which can be reduced further by harnessing the waste heat from the industrial plants and solar energy.