Filter Sand-Phosphate Buffer Effect on 2,4-Dinitrotoluene Ozonation

The objective of this study is to evaluate the effects of different sands and phosphate buffer on ozone decomposition by measuring the observed ozone decomposition rate constant of three different natural sands at pH 7 with and without the presence of phosphate buffer and with and without sand (i.e., aqueous ozone only). In addition, this study evaluated phosphate buffer effect on the heterogeneous catalysis of ozone for the destruction of 2,4-dinitrotoluene (DNT) by measuring the observed DNT degradation rate constant (kDNT). Ozone decomposition rates in the presence of NaOH buffer and sand were up to 7.9 times greater and 3.4 times in the presence of phosphate. In the absence of phosphate, sand reduced the observed rate of DNT degradation. In the presence of phosphate, sands enhance the observed DNT degradation rate by a factor approximately proportional to their surface manganese concentration. A proposed mechanism was developed explaining the observed effects of the phosphate in a sand ozone system.