Reactive-Transport Modeling of Oxidation Pathways of Insensitive High Munitions in Porous Flow-Through Electrodes

A mathematical reactive-transport model was developed to investigate the electrochemical oxidation pathways of 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and 3-nitro-1,2,4-triazol-5-one (NTO), which are insensitive high explosives (IHEs) produced by the Department of Defense. Proposed electrochemical oxidation pathways for DNAN, NQ, and NTO were validated using reactive-transport modeling, density functional theory (DFT) simulations, and experimental data. The reactive-transport model was calibrated to experimental data collected with and without NaCl to evaluate the effects of hydroxyl radicals (OH•) and the chlorine evolution reaction (CER) on IHE oxidation pathways. DFT simulations provided further insight into the reactions between IHE and reactive chlorine species (RCSs). The findings revealed that the initial electrochemical oxidation step of DNAN and NTO was primarily by direct electron transfer, with minimal contribution from reactions with OH•. In contrast, NQ exhibited electrode surface blocking due to electrochemical polymerization in the absence of NaCl. However, the presence of NaCl generated RCSs that reacted with NQ, reducing electrode surface blocking. The model also accounted for solvent decomposition and background species reactions, providing a comprehensive understanding of the electrochemical oxidation processes for DNAN, NQ, and NTO. The model can be applied to guide electrochemical treatment of IHEs at Department of Defense sites.