The kinetics of the oxidation of chromium(II), titanium(III), and vanadium(IV) by hydrogen peroxide and hydroxyl radicals

The reaction rate constants of Mⁿ⁺ + H₂O₂ were measured for Mⁿ⁺ = Cr^II, Ti^III, and V^IV, using the stopped-flow technique, in perchloric and sulphuric acid media. These rate constants, for T^III and V^IV were found to increase on increasing the pH in the range 0-2.5. The rate constants for the reaction of these metal ions with OH radicals were measured through competition with thiocyanate anions, using the pulse radiolysis technique. It was found that k_Mⁿ⁺+OH = (1.2 ± 0.2) × 10¹⁰, (3.0 ± 0.3) × 10⁹, and (6.4 ± 04) × 10⁸M^-1 s^-1 for Cr^II, Ti^III, and V^IV respectively.