A novel D2EHPA-based synergistic extraction system for the recovery of chromium (III)

• Cr (III) was recovered by D2EHPA–isooctanol synergistic extraction system.
• Influence factors in synergistic extraction process were studied in detail.
• Stripping of Cr (III) from the synergistic extraction system was investigated.
• Mechanism on Cr (III) extraction by mixed extractant was studied by UV–vis, FT-IR.

A synergistic solvent extraction method for recovering chromium (III) was proposed using the mixed extractant consisting of di (2-ethylhexyl) phosphoric acid (D2EHPA) and isooctanol. Based on the synergistic effect and the price of extractant, isooctanol was selected as the effective synergistic extractant in the D2EHPA-based extraction system. The chromium (III) extraction was found to increase and then decrease with increasing isooctanol concentration. The effects of D2EHPA concentration, initial pH, contact time, temperature, and anions concentration on the synergistic extraction of chromium (III) were investigated. The comparative study on the stripping of chromium from the loaded D2EHPA–isooctanol and the loaded D2EHPA was carried out. Based on the experiment results and the analysis of UV–vis and FT-IR spectra, the mechanism on the synergistic extraction of chromium (III) by D2EHPA–isooctanol mixed extractant was discussed.