Electrochemical reduction of simulated munitions wastewater in a bench-scale batch reactor

2,4,6-Trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are major constituents of munitions production wastewater discharged from explosive manufacturing units and munitions load, assembly, and pack operations. Experiments were carried out to study the electrochemical reduction of DNT and a mixture of TNT and RDX. The effect of various parameters including current, stir rate, and presence and absence of dissolved oxygen was investigated. Experiments were conducted using glassy carbon rods as the cathode and platinum wire as the anode. End products were also analyzed for the experiments to obtain molar balance closure for the conversion of the nitroaromatic to intermediates. The experimental results showed that the electrochemical reduction of nitroaromatics follow pseudo first-order rate kinetics. The first-order rate constants for the reduction of nitroaromatics were observed to increase with an increase in current or stir rate. The rate of reduction of the nitroaromatics was observed to be significantly higher under anoxic conditions (dissolved oxygen = 0.2 mg/L) than under anoxic conditions (dissolved oxygen = 8.4 mg/L). A molar balance closure of 60-90% could be obtained for experiments conducted under oxic conditions.