Extraction of boron from salt lake brine using 2-ethylhexanol

• Extraction process was investigated for boron from real salt lake brine.
• Extraction reaction using 2-ethylhexanol was exothermic.
• Washing step using the stripping solution significantly improved product purity.
• Process parameters were optimized to obtain a boron of 99.5%.

A systematic investigation on the extraction of boron from salt lake brine using 2-ethylhexanol as the extractant is reported with an emphasis on the extraction thermodynamics and extraction process design in order to obtain high purity boron product. The extraction parameters were optimized with respect to the time of extraction, volume percentage of extractant, phase ratio, and the concentration of magnesium. Logarithm linear regression revealed an average association constant of 0.7 for 2-ethylhexanol and boric acid. Thermodynamic modeling results indicate that the association is an exothermic, enthalpy driven process. A three-stage countercurrent extraction and stripping was designed in order to assess the process feasibility. Results showed an overall boron extraction efficiency of 99.5% with a purity of 95.5%. In addition, attempts were also made on improving the product purity with a two-stage washing step. These results indicate the application potential of present extraction process.