Synergistic extraction of vanadium(IV) in sulfuric acid media using a mixture of D2EHPA and EHEHPA

In the present study, the mechanisms and thermodynamics of vanadium extraction by a mixture of bis-2-ethylhexyl phosphorous acid (D2EHPA) and 2-ethylhexyl phosphorous acid mono-2-ethylhexyl ester (EHEHPA) from sulfate medium were investigated. It was found that the maximum synergistic factors obtained at XD2EHPA = 0.2 and the reaction of the synergistic extraction is exothermical. Results showed that the mixture system in the presence of complexing agents exhibit a higher extraction efficiency and require a lower acid consumption during the stripping process of vanadium. Fourier transform infrared (FT-IR) spectroscopy showed that P-O-H and PO of the extractants are responsible for the synergistic extraction of VO2 + species by cation exchange mechanism and some hydrogen bonds between EHEHPA and D2EHPA formed in the synergistic extraction system. With the slope analysis method, the reaction of the synergistic extraction was mainly predicted.