Enhanced Reactivity of Superoxide in Water−Solid Matrices

Superoxide is unreactive in deionized water, but aqueous systems containing added solvents, including H2O2 at >100 mM, show significantly increased reactivity of superoxide with oxidized organic compounds such as highly chlorinated aliphatics. The potential for solid surfaces to similarly increase the reactivity of superoxide in water was investigated. Heterogeneous birnessite (γ-MnO2)-catalyzed decomposition of H2O2 promoted the degradation of the superoxide probe hexachloroethane (HCA) at H2O2 concentrations as low as 7.5 mM, while no measurable HCA degradation was found in parallel homogeneous iron(III)−EDTA−H2O2 systems at H2O2 concentrations