Study on the synergistic extraction of vanadium by mixtures of acidic organophosphorus extractants and primary amine N1923

•Mixtures of organophosphorus acids and N1923 were used for the extraction of V(IV).•Extraction effects of V(IV) with the mixtures were investigated.•Extracted complexes and equilibrium constants were determined with D2EHPA+N1923.•The synergistic extraction of V(IV) with D2EHPA+N1923 is endothermic in nature.•The synergistic extraction system had potential to separate vanadium, nickel, and chromium. In the present study, the solvent extraction of vanadium from chloride medium with acidic organophosphorus extractants, primary amine N1923, and their mixtures were investigated. The organophosphorus acids included di(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP), and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272). The extraction effects from chloride medium were studied in detail, illustrating that all the three mixtures of organophosphorus acids and N1923 have synergistic effects on vanadium. As a representative, extraction stoichiometries of vanadium with D2EHPA+N1923 were studied with the methods of slope and constant mole. The extraction capacity of temperature dependency was also investigated. Moreover, the separation of vanadium, nickel, and chromium with mixtures of D2EHPA+N1923 was studied.