Science & Technology: More Efficient Extraction of Lithium from Geothermal Brine

A Quantitative Metric for the Design of Selective Supercritical CO2 Extraction of Lithium from Geothermal Brine (Wiley Online Library)

By Andrew W. Ruttinger, Cornell University, Ithaca NY, USA, et al. 

As demand grows for lithium, its recovery from geothermal brines provides an attractive alternative to slow mining. One promising extraction method uses crown ethers as extractants in supercritical carbon dioxide with cation exchangers to facilitate extraction from brine.

Binding free energy gives a suitable metric to describe extraction efficiency. Differences in the binding free energies of sodium and lithium to crown ethers determine the extraction selectivity. Fluorine groups are found to exert a positive influence to optimize extraction efficiency. Of the systems studied, F14C4 with TPFOS offers the most selective and efficient extraction system.

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