Oxidation of Binary DNAPL Mixtures Using Potassium Permanganate with a Phase Transfer Catalyst

Phase transfer catalysts (PTCs) can enhance the oxidation of pure DNAPLs using potassium permanganate by facilitating reactions in the organic phase. This study examined the influence of pentyltriphenylphosphonium bromide (PTPP) as a PTC on the rate of permanganate (MnO 4 ‐ ) oxidation of DNAPLs in pure phases and mixtures. Kinetic batch experiments with trichloroethylene (TCE), 1,1,2‐trichloroethane (TCA), tetrachloroethylene (PCE), 1,1,2,2‐tetrachloroethane (TECA), and their mixtures, (1:1, v/v) were performed in test tubes to assess reaction rates. The disappearance of MnO 4 ‐ was quantified by capturing digital images pf the tubes. This rapid photographic monitoring approach was validated by comparison with an UV‐Vis spectrometer method. The PCE/TCA mixture was selected to examine the impact of relative contents of a component in the binary mixture on the MnO 4 ‐ disappearance. The comparative rates of MnO 4 ‐ consumption for pure phases were TCE > TECA > PCE > TCA. PTPP increased MnO 4 ‐ consumption rates, especially for TCE and TECA as pure, phases. The consumption rates of mixtures without PTPP were lower than those including the pure phases. However, due to their high extraction capability for PTPP‐MnO 4 ‐ ion pairs, TCA and TECA appeared to increase the MnO 4 ‐ consumption significantly when they were mixed with TCE or PCE, The increase in consumption rates with PTPP was most remarkable with the mixture of PCE and TCA. Chloride concentration showed faster increases for the mixtures with relative PCE contents ranging about 5 % to 90%, maximum at about 50% PCE, than for pure phases of PCE and TCA when the PTC assisted the reactions. The PTC appears to be promising in its ability to increase oxidation rates of DNAPL mixtures.