In situ colloidal MnO2 deposition and ozonation of 2,4-dinitrotoluene

Laboratory experiments are presented that demonstrate a novel in situ semip assive reactive barrier for the degradation of 2,4 dinitrotoluene created b y coating aquifer surfaces by deposition of colloidal MnO2, which catalyzes ozone degradation and enhances contaminant oxidation. Ozone is added to th e reactive barrier and is transported through the zone with the contaminant s by existing hydraulic gradients. The communication presents the prelimina ry laboratory investigation demonstrating the viability of this method. Stu dies were conducted by coating Ottawa sand with colloidal MnO2. Results sho w that concentrations of MnO2 in the range of 0.2 mg/g can be deposited wit h no measurable change in hydraulic conductivity, that there is significant coverage of the sand material by MnO2, and the deposition was not reversib le under a wide range of chemical conditions. Ozonation of 2,4-dinitrotolue ne in the presence of MnO2-coated sand was demonstrated to result in pseudo -first-order degradation kinetics with respect to DNT with half-lives rangi ng from 28 to 22 min (at pH 6 and 7, respectively), approximately 25% faste r than experiments performed in the absence of MnO2.