Green recovery of low-concentration lithium from high-temperature geothermal fluids

Abstract

Geothermal fluids represent a novel source of liquid lithium resources, but extracting lithium from such sources is challenging due to their inherent high-temperature and low-concentration characteristics. Herein, a high-temperature-resistant inorganic composite specifically for lithium extraction from geothermal fluids was developed. By leveraging a high-temperature conversion mechanism, β-Li₂TiO₃ with enhanced adsorption properties for low-concentration lithium was synthesized in a controllable and large-scale manner. Because using AlOOH·nH₂O as the precursor for Al₂O₃ enables the preparation of β-Al₂O₃ without inducing a crystal phase transformation in β-Li₂TiO₃. It allows an in situ conversion procedure to produce β-Al₂O₃-supported β-Li₂TiO₃ (Li₂TiO₃/β-Al₂O₃) with high thermal stability and a large specific surface area. To achieve granulation of the highly viscous AlOOH·nH₂O slurry containing β-Li₂TiO₃, a droplet-forming device equipped with a high-pressure pneumatic metering pump was further designed and constructed, by which the large-scale preparation of Li₂TiO₃/β-Al₂O₃ was accomplished. Investigation into the adsorption mechanism and kinetics of Li₂TiO₃/β-Al₂O₃ revealed that lithium uptake is primarily driven by β-Li₂TiO₃, and elevated temperatures favor the extraction process. When applied to a high-temperature (353 K) geothermal fluid containing low-concentration lithium (25.85 mg·L⁻¹), an adsorption capacity of 22.92 mg·g⁻¹ with more than 90% recovery rate was achieved. Because of the minimal environmental impact, this method offers a promising strategy for sustainable lithium extraction from geothermal fluids.