Columbia University extracts lithium from synthetic brine with thermo-responsive solvent

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. Published in the journal Joule, the study shows that lithium can be separated without relying on conventional solar evaporation ponds or hard-rock mining.

Solvent behavior and selectivity

The extraction process relies on a solvent that alters its affinity for water based on temperature. At room temperature, the liquid chemical absorbs both water and lithium directly from the brine. 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. According to Yip, this desorption step requires only low-grade thermal energy, which can be supplied by industrial waste heat or solar collectors.

Natural brines contain high concentrations of chemically similar alkali metals, particularly sodium and potassium, complicating lithium isolation. The solvent maintained a chemical preference for lithium even when lithium concentrations were 1,000 times lower than those of competing ions. 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. 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.

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. 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.