Oxidation of Vanadium(lll)by Hydrogen Peroxide and the Oxomonoperoxo Vanadium(V)Ion in Acidic Aqueous Solutions:A Kinetics and Simulation Study

摘要

The reaction between vanadium(lll)and hydrogen peroxide in aqueous acidic solutions was investigated.The rate law shows first-order dependences on both vanadium(lll)and hydrogen peroxide concentrations,with a rate constant,defined in terms of-d[H_2O_2]/df,of 2.O_6(+-)0.O_3 L mol~(-1)s~(-1)at 25 degC;the rate is independent of hydrogen ion concentration.The varying reaction stoichiometry,the appreciable evolution of dioxygen,the oxidation of 2-PrOH to acetone,and the inhibition of acetone formation by the hydroxyl radical scavengers,dimethyl sulfoxide and sodium benzoate,point to a Fenton mechanism as the predominant pathway in the reaction.Methyltrioxorhenium-(VII)does not appear to catalyze this reaction.A second-order rate constant for the oxidation of V~(3+)by OV(O_2)~+ was determined to be 11.3(+-)0.3 L mol~(-1)s~(-1)at 25 degC.An overall reaction scheme consisting of over 20 reactions,in agreement with the experimental results and literature reports,was established by kinetic simulation studies.