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.