Kinetics of Contaminant Degradation by Permanganate

To provide a more complete understanding of the kinetics of in situ chemical oxidation (ISCO) with permanganate (MnO₄^-), we measured the kinetics of oxidation of 24 contaminantsmany for which data were not previously available. The new data reported here were determined using an efficient method based on continuous measurement of the MnO₄^- concentration by absorbance spectrometry. Under these conditions, the kinetics were found to be first-order with respect to both contaminant and MnO₄^- concentrations, from which second-order rate constants (k‘ ‘) were readily obtained. Emerging contaminants for which k‘ ‘ was determined (at 25 °C and pH 7) include 1,4-dioxane (4.2 × 10^-5 M^-1 s^-1), methyl t-butyl ether (MTBE) (1.0 × 10^-4 M^-1 s^-1), and methyl ethyl ketone (MEK) (9.1 × 10^-5 M^-1 s^-1). Contaminants such as 2,4,6-trinitrotoluene (TNT), the pesticides aldicarb and dichlorvos, and many substituted phenols are oxidized with rate constants comparable to tetrachloroethene (PCE) and trichloroethene (TCE) (i.e., 0.03−1 M^-1 s^-1) and therefore are good candidates for remediation with MnO₄^- in the field. There are severalsometimes competingmechanisms by which MnO₄^- oxidizes contaminants, including addition to double bonds, abstraction of hydrogen or hydride, and electron transfer.