Abstract:
Analytical methodologies for characterization and determination of vanadium in vanadium electrolyte solutions in sulphuric acid media have been developed. Determination of total vanadium over a wide concentration range was performed using atomic absorption spectrometric technique for the ppm region, and by UV-VIS spectrophotometric and potentiometric techniques for the higher concentration region. Standard addition was required for determination of total vanadium and trace impurities, such as Cu, Fe and Pb, in vanadium electrolyte solution. Influence of matrix or ionic environment of vanadium, e.g. acid content, sulphate ion and trace impurities was carefully studied. The unique characteristics of UV-VIS absorption spectra of vanadium species with various oxidation states were systematically studied and applied for speciation of vanadium species in standard mixtures and in real samples. The first derivative spectra have the advantages of overcoming overlap of peaks and identifying characteristic wavelengths. Moreover, the stability of V(III) species in H(,2)SO(,4) solution with and without chloride ion was also investigated. The acid-base and oxidation-reduction behaviours of vanadium species were studied by potentiometric techniques, using combination glass and Pt electrodes, respectively. V(III) and V(IV) species exhibited less proton affinities than V(V) species. Comparisons between UV-VIS spectrophotometric and potentiometric techniques for speciation of vanadium species with different oxidation states are summarized.