Oxidation of hexacyanoferrate(II) by peroxodisulphate in aqueous perchloric acid-A kinetic and mechanistic study

1090-1094The kinetics of the reaction between hexacyanoferrate(II) and peroxodisulphate has been studied spectroscopically in perchloric acid. The reaction is first order each in peroxodisulphate and hexacyanoferrate(II) concentrations. Increase in perchloric acid concentration increases the reaction rate. The order with respect to perchloric acid concentration is less than unity. The active species of hexacyanoferrate(II) and peroxodisulphate are HFe(CN)₆³⁻ and S₂O₈²⁻ respectively. A suitable mechanism is proposed for the studied reaction. The thermodynamic quantities with respect to the first step and the activation parameters with respect to the slow step of the mechanism have been calculated. Numerical simulation with this mechanism agrees well with the experimental results