22 Apr 2021

Computational Investigation on Interactions between Some Munition Compounds and Humic Substances

Note: This document was originally published as a journal article or conference proceeding. The link and document will be accessible after a 12-month embargo expires (December 14, 2021 for this document). For more information, see "Frequently Asked Questions on Public Access to Federally Funded Journal Articles" at https://discover.dtic.mil/pdfs/padf/DTIC_FAQs_Public_Access.pdf Abstract: Humic acid substances (HAs) in natural soil and sediment environments affect the retention and degradation of insensitive munition compounds and legacy high explosives (MCs): 2,4-dinitroanisole (DNAN) DNi−NH4+, N-methyl-p-nitroaniline (nMNA), 1-nitroguanidine (NQ), 3-nitro-1,2,4-triazol-5-one (NTO; neutral and anionic forms), 2,4,6-trinitroto-luene (TNT), and 1,3,5-trinitro-1,3,5-triazinane (RDX). A humic acid mode compound has been considered using molecular dynamics, thermodynamic integration, and density functional theory to characterize the munition binding ability, ionization potential, and electron affinity compared to that in the water solution. Humic acids bind most compounds and act as both a sink and source for electrons. Ionization potentials suggest that HAs are more susceptible to oxidation than the MCs studied. The electron affinity of HAs is very conformation-dependent and spans the same range as the munition compounds. When HAs and MCs are complexed, the HAs tend to radicalize first, thus buffering MCs against reductive as well as oxidative attacks.