Sustainable lithium extraction and magnesium hydroxide co-production from salt-lake brines

Abstract

In recent years, the demand for lithium (Li) has been on the rise as Li-ion batteries are playing an increasingly important role in powering the global transition to a low-carbon society. In contrast to the predominant production of lithium from hard rock, lithium extraction from brine sources has proven more economical and sustainable. However, substantial challenges remain, including the low efficiency of the extraction process, especially for brines of high salinity, complex composition and poor selectivity against magnesium, the major competing species. Here we show a loose nanofiltration process involving ethylenediaminetetraacetic acid (EDTA) for direct and efficient Li+ extraction as well as effective Mg2+ utilization from salt-lake brines. Taking advantage of selective binding between EDTA4− and Mg2+, our process achieves ultrahigh Mg2+ rejection of 99.85%, ultrafast Li+ flux of ~4.34 mol m−2 h−1 and unprecedented Li+/Mg2+ separation factor (~679) under industrial conditions (127.06 g l−1). More importantly, the Li+ recovery rate reaches 89.90% through a two-stage filtration process, while Mg2+ waste is converted to nanostructured Mg(OH)2 and 98.87% of EDTA4− can be regenerated. Our scalable process minimizes environmental impact while maximizing resource utilization, thereby catalysing the shift toward a more sustainable future. The global race to a net-zero economy depends heavily on lithium—to power electric vehicles and to store renewable energy. Here the authors show a selective lithium extraction process from salt-lake brines, together with magnesium utilization.