Oxidative Degradation of 2,4,6-Trinitrotoluene by Ozone in an Electrohydraulic Discharge Reactor

Abstract

The electrohydraulic discharge process in the presence of ozone has been used to investigate the rapid degradation and mineralization of aqueous 2,4,6-trinitrotoluene (TNT) solutions that were directly exposed to high-energy electrical discharges between two submerged electrodes. The 165 μM solutions of TNT were completely (>90%) mineralized over the course of 300 electrical discharges of 7 kJ each. The kinetics of TNT degradation were investigated as a function of the aqueous-phase ozone concentration, pH, discharge energy, and electrode gap length. The rate of TNT degradation increases with an increase in aqueous-phase ozone concentration of up to 150 μM, an increase in pH from 3.0 to 7.9, an increase in discharge energy from 5.5 to 9 kJ, and a decrease in the electrode gap length from 10 to 6 mm. The rapid rates of mineralization (e.g. 12 ms) are attributed to the action of UV light in the reactor chamber on O_3 to produce a high flux of hydroxyl radicals per discharge (1 μM discharge^(-1)). The primary reaction intermediates were 2,4,6-trinitrobenzaldehyde and trinitrobenzene.