Comparison of potassium permanganate and hydrogen peroxide as chemical oxidants for organically contaminated soils

Laboratory experiments were completed to compare the treatment efficiency of KMnO4 with H2O2 (alone or with amendments) for sand and silty clay soil contaminated with either a mixture of volatile organic compounds (VOCs) [trichloroethylene (TCE), tetrachloroethene (PCE), and 1,1,1-trichloroethane (TCA)] or semivolatile organic compounds (SVOCs) (naphthalene, phenanthrene, and pyrene). The relatively treatment effects of soil type, oxidant loading rate and dosing, and reaction period, as well as the use of surfactant or iron amendments and pH adjustment were examined using batch experiments with contaminated soil slurries. When KMnO4 was applied to low organic carbon, acidic, or alkaline soils, at loading rates of 15-20 g/kg it was found to degrade consistently 90% or more of the alkene VOCs (TCE and PCE) and 99% of the polyaromatic SVOCs (naphthalene, pyrene, and phenanthrene). H2O2 was more sensitive to contaminant and soil type and VOC treatment efficiencies were somewhat lower as compared with KMnO4 under comparable conditions, particularly with the sandy soil and even when supplemental iron was added. In clay soil, H2O2 with iron addition degraded over 90% of the SVOCs present compared with near zero in sandy soil, unless the pH was depressed to pH 3 and iron amendments were increased, whereby the treatment efficiency in the sandy soil was increased slightly. With both H2O2 and KMnO4, treatment efficiency increased to varying degrees as the oxidant loading rate (g/kg) and reaction time (h) were increased. Multiple oxidant additions or surfactant addition were not found to have any significant effect on VOC treatment efficiency. Also, very limited TCA treatment was observed with either H2O2 Or KMnO4.