Speciation of vanadium (V) extracted from acidic sulfate media by trioctylamine in n-dodecane modified with 1-tridecanol

The speciation of vanadium (V) extracted from acidic sulfate media by protonated trioctylamine in n-dodecane modified with 5% (wt) 1-tridecanol has been investigated by Fourier transformed infrared spectroscopy (FTIR) and ⁵¹V nuclear magnetic resonance spectroscopy (⁵¹V NMR). In aqueous sulfate solutions, vanadium (V) exists both as VO₂⁺ and VO₂SO₄⁻ ions. The FTIR spectra of 0.2 mol kg^− 1 protonated trioctylamine in n-dodecane modified with 5% (wt) 1-tridecanol, loaded with various concentrations of vanadium (V) by extraction from 1 mol kg^− 1 H₂SO₄, indicate that vanadium (V) exists in organic phases as polyvanadates, likely as decavanadates. The condensed nature of the extracted form of vanadium (V) was neither confirmed nor precluded by ⁵¹V NMR as the micellar structure of these organic phases imposes local conditions which allow the transformation of VO₂⁺ and VO₂SO₄⁻ into polyvanadates, but also modify the chemical shifts compared to the ones observed in bulk aqueous solutions for mononuclear and polynuclear vanadium (V) species.