Columbia University extracts lithium from synthetic brine with thermo-responsive solvent
Engineers demonstrated a laboratory method that extracts lithium using temperature-triggered solvent shifts, bypassing traditional solar ponds.
Columbia University engineers have demonstrated a laboratory proof of concept to extract lithium from salty water using a temperature-responsive solvent, Earth.com reported 
earth.comEarth.comearth.comOpen source ↗. The researchers, led by associate professor Ngai Yin Yip, tested the liquid chemical system on simulated brine formulated to mirror the geothermal waters of California's Salton Sea earth.comEarth.comearth.comOpen source ↗. Published in the journal Joule, the study shows that lithium can be separated without relying on conventional solar evaporation ponds or hard-rock mining earth.comEarth.comearth.comOpen source ↗.
Solvent behavior and selectivity
The extraction process relies on a solvent that alters its affinity for water based on temperature earth.comEarth.comearth.comOpen source ↗. At room temperature, the liquid chemical absorbs both water and lithium directly from the brine earth.comEarth.comearth.comOpen source ↗. Upon applying modest heat, the solvent switches to repelling water, releasing a purified stream containing the extracted lithium while returning to its initial state for subsequent cycles earth.comEarth.comearth.comOpen source ↗. According to Yip, this desorption step requires only low-grade thermal energy, which can be supplied by industrial waste heat or solar collectors earth.comEarth.comearth.comOpen source ↗.
Natural brines contain high concentrations of chemically similar alkali metals, particularly sodium and potassium, complicating lithium isolation earth.comEarth.comearth.comOpen source ↗. The solvent maintained a chemical preference for lithium even when lithium concentrations were 1,000 times lower than those of competing ions earth.comEarth.comearth.comOpen source ↗. In tests with simulated Salton Sea brine, the system demonstrated selectivity ratios of approximately 13 to 1 over sodium and 24 to 1 over potassium earth.comEarth.comearth.comOpen source ↗. Because the solvent is alkaline, it also caused dissolved magnesium contaminants to precipitate out as solids, resulting in the complete removal of magnesium from the treated mixture earth.comEarth.comearth.comOpen source ↗.
Lab recovery and scaling limits
Over four consecutive operating cycles using a single batch of solvent, the setup extracted nearly 40% of the lithium dissolved in the simulated brine earth.comEarth.comearth.comOpen source ↗. The authors noted that approximately 60% of the target metal remained unrecovered, as the early-stage setup has not yet been optimized for maximum yield or processing efficiency earth.comEarth.comearth.comOpen source ↗. The researchers noted that real-world geothermal brines contain additional impurities that were absent in the synthetic mixtures, meaning the technology's selective performance and capacity must still be verified under industrial plant conditions earth.comEarth.comearth.comOpen source ↗.
