Toward mechanistic understanding of highly extraction efficiency for boron from Salt Lake brine: kinetics, mass transfer, and modeling

BACKGROUND

The kinetic study of boron extraction from Salt Lake brine is the essence and mechanism of solvent extraction process. A thorough understanding of the kinetic competition between desired Ionic liquid (IL)-isooctyl alcohol (2-EH) extraction processes and any detrimental diffusion resistance is required to achieve high extraction efficiency of boron in Salt Lake brine.

RESULTS

The extraction experiments of boron from Salt Lake brine with highly extraction efficiency (93.6%) in 3-dodecyl-1-methylimidazolium hydrogen sulfate ([C₁₂mim][HSO₄])-2-EH extraction system was performed in a constant interfacial area stirred Lewis cell. The work uniquely employs a laminar constant interface surface cell as the research object, offering a more precise measurement of the extraction kinetics compared to traditional methods. Furthermore, the impacts of key parameters such as extraction temperature, stirring speed, phase interface area, and the initial concentrations of boron [C₁₂mim][HSO₄] and 2-EH were thoroughly examined, revealing their significant influence on extraction efficiency.

CONCLUSION

The results showed that the extraction process mainly occurred in the two-phase interfacial region and was controlled by aqueous diffusion reaction. The activation energy was determined to be about 23.90 kJ·mol⁻¹. Meanwhile, thermodynamic parameters (ΔH, ΔS, and ΔG) revealed that the extraction of boron was an endothermic and non-spontaneous process. According to data analysis, boron extraction is approximately first-order, and a novel rate equation and extraction mechanism are proposed. The results will provide referential values for the development of more efficient separation processes. © 2025 Society of Chemical Industry (SCI).