Sustainable Recovery of Lithium from Contaminated Soil through Halophyte Salt Excretion

Increasing levels of lithium (Li) contamination, caused by ongoing escalations in Li production, represent a contemporary environmental issue that requires effective resolution. Phytoremediation, in which metals in contaminated soil are accumulated by plants for remediation, is energy- and cost-intensive, as the recovered plants are typically burned with the aim of concentrating the metals. In this study, we propose a Li recovery method that entails harvesting the salts excreted by Li-tolerant halophytes. Acids exuded from the roots of halophytic Rhodes grass can leach Li⁺ ions from soil-borne Li ore, thereby facilitating Li absorption via the roots and subsequent excretion through leaf salt glands. Li concentrations in the salts excreted by Rhodes grass grown in soil containing Li ore (amblygonite) at 200 mg Li kg^-1 were 110-fold higher than those in the soil. Efficient recovery of Li from Li-containing soil as excreted salts thus reduces soil contamination and ultimately contributes to a sustainable Li cycle with low environmental impact.