Boron (B) and lithium (Li) are two key elements in salt lake brine. The increasing demand for them has prompted people to pay more attention to their extraction. Traditional extraction methods often suffer from environmental hazards and process complexity, limiting their industrial applicability.

In a study published in Journal of Hazardous Materials, the research group led by Prof. SUN Xiaoqi from Fujian Institute of Research on the Structure of Matter (FJIRSM) of Chinese Academy of Sciences, reported a type of green solvents called deep eutectic solvents which are thermally stable, low volatility, low-cost, easy to synthesize. Deep eutectic solvents, especially low melting point mixed solvents (LoMMs), have significant advantages in the field of extraction and separation due to their adjustable properties and environmental sustainability.

The researchers developed some LoMMs, which use trioctylphosphine oxide as a hydrogen bond acceptor and 2-ethyl-1,3-hexanediol as a hydrogen bond donor for selective extraction of boric acid from salt lake brine. Under optimized conditions, the extraction experiment showed that the extraction system achieved a 99% B extraction rate.

The mechanism study of Fourier-transform infrared spectra and quantum chemical calculations confirmed the formation of stable B complexes through hydrogen bonding and esterification reactions.

After removing B, the researchers used a novel LoMMs composed of menthol, tributyl phosphate, and FeCl₃ to synergistically extract Li, achieving an extraction rate of 82%.

This study demonstrates the potential of a comprehensive resource extraction strategy for salt lake brine based on LoMMs.

Illustration of the Research (Image by Prof. SUN’s group)

Contact:

Prof. SUN Xiaoqi

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: xqsun@fjirsm.ac.cn