Computational Investigation on Interactions between Some Munition Compounds and Humic Substances

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 − NH 4 +, N-methyl-p-nitroaniline (nMNA), 1-nitroguanidine (NQ), 3nitro-1,2,4-triazol-5-one (NTO; neutral and anionic forms), 2,4,6-trinitrotoluene (TNT), and 1,3,5-trinitro-1,3,5-triazinane (RDX). A humic acid model 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.

Properties and Mechanisms for PFAS Adsorption to Aqueous Clay and Humic Soil Components

“…Additionally, having been well characterized and parameterized with the ClayFF force field made this substance an attractive candidate for our studies. The structure of the humic substance model comes from previous literature, includes all the most prominent structural features that have been identified for humic materials, and is a representative of a major component of the organic carbon content found in soils . In the literature, meta-analysis approaches have been used to link the fate and transport models to the underlying binding phenomenology. − By investigating PFAS interactions with clays and organic carbons, we begin to elucidate the individual mechanisms of PFAS sorption.…”

Properties and mechanisms for PFAS adsorption to aqueous clay and humic soil components

“…The structure of the humic substance model comes from previous literature, 24 includes all the most prominent structural features that have been identified for humic materials, and is a representative of a major component of the organic carbon content found in soils. 25 In the literature, meta-analysis approaches have been used to link the fate and transport models to the underlying binding phenomenology. 26−29 By investigating PFAS interactions with clays and organic carbons, we begin to elucidate the individual mechanisms of PFAS sorption.…”

New liquid chromatography columns for highlighting the interaction of ligand candidates with humic acid

“…HA molecular dynamic models were developed to characterize the molecular binding mechanism of HSs with molecular ligands [10–14]. Among these models, the structural properties of the Temple Northeastern‐Birmingham HA monomer model [15, 16] were in good agreement with the real experimental conditions [16].…”