Ion-selective properties of metastable (VO)0.09V0.18Mo0.82O3 · 0.54H2O

This paper describes a thin-film solid electrode with an ion-sensitive membrane based on the mixed oxide (VO)0.09V0.18Mo0.82O3 · 0.54H2O. The electrode is selective for tetravalent vanadium in the concentration range 3 ≤ pCV4+ ≤ 5 and acidity range 4.5 ≤ pH ≤ 6, with a slope close to the theoretical value. In the range 1 ≤ pH < 5, the electrode responds to changes in hydrogen ion concentration, with a slope of 50 ± 2 mV/pH. Its alkali-metal-ion response shows up in the range 1 ≤ pCM+ ≤ 4 for pH ≥ 6. We examine the effect of the Li+, K+, Na+, Cs+, Rb+, Mg2+, Ca2+, Sr2+, Ba2+, Co2+, Ni2+, Mn2+, Al3+, Cr3+, and VO2+ ions on the potential of the electrode and determine its selectivity coefficients for these cations.