Iron and Electron Shuttle Mediated (Bio)degradation of 2,4-Dinitroanisole (DNAN)

Abstract

The Department of Defense has developed explosives with the insensitive munition 2,4-dinitroanisole (DNAN), to prevent accidental detonations during training and operations. Understanding the fate and transport of DNAN is necessary to assess the risk it may represent to groundwater once the new ordnance is routinely produced and used. Experiments with ferrous iron or anthrahydroquinone-2,6-disulfonate (AHQDS) were conducted from pH 6.0 to 9.0 with initial DNAN concentrations of 100 μM. DNAN was degraded by 1.2 mM Fe(II) at pH 7, 8, and 9, and rates increased with increasing pH. Greater than 90% of the initial 100 μM DNAN was reduced within 10 min at pH 9, and all DNAN was reduced within 1 h. AHQDS reduced DNAN at all pH values tested. Cells of Geobacter metallireducens were added in the presence and absence of Fe(III) and/or anthraquinone-2,6-disulfonate (AQDS), and DNAN was also reduced in all cell suspensions. Cells reduced the compound directly, but both AQDS and Fe(III) increased the reaction rate, via the production of AHQDS and/or Fe(II). DNAN was degraded via two intermediates: 2-methoxy-5-nitroaniline and 4-methoxy-3-nitroaniline, to the amine product 2,4-diaminoanisole. These data suggest that an effective strategy can be developed for DNAN attenuation based on combined biological-abiotic reactions mediated by Fe(III)-reducing microorganisms.

Different Mechanisms of Alkaline and Enzymatic Hydrolysis of the Insensitive Munition Component 2,4-Dinitroanisole Lead to Identical Products

“…However, contrary to expectations from the large normal C-AKIE, which implies a preferential transformation of C isotopologues of DNAN, DNP is not enriched in C compared to DNAN. In fact, even after 30% of DNAN conversion (i.e., c/c 0 = 0.7, Figure 1a) the δ 13 C of DNP is larger than that of DNAN, meaning that the produced DNP contains more 13 group was isotopically very light (−99 to −110 ) and substantially more negative than existing data for this functional group in organic compounds. 43 While the magnitude of C isotope fractionation due to alkaline hydrolysis of DNAN to DNP quantified with eqs.…”

“…To derive C or N isotope enrichment factors ( C and N ) for each reaction, eqs. 1 and 2 below were fit to the measured 13 C/ 12 C and 15 N/ 14 N ratios.…”

“…The nitroaromatic compound (NAC) 2,4-dinitroanisole (DNAN), developed as an alternative to 2,4,6-trinitrotoluene (TNT), is of particular interest due to its potential toxicity. 5,6 Similar to other NACs, 3,[7][8][9][10] DNAN can be reduced to the corresponding aromatic amines [11][12][13][14] and transformed photolytically. [15][16][17] Interestingly, DNAN can also be hydrolyzed either abiotically at high pH 18,19 or biologically by DNAN O-demethylase from Nocardioides sp.…”

Anaerobic Bacterial Immobilization and Removal of Toxic Sb(III) Coupled With Fe(II)/Sb(III) Oxidation and Denitrification

“…Fe(II) is more stable at neutral or alkaline pH in anoxic environments (Kappler and Straub, 2005). The Fe redox reactions are coupled with carbon, nitrogen, oxygen and sulfur cycles and are involved in important environmental processes such as methane oxidation, aromatic hydrocarbon degradation, heavy metal passivation and immobilization (Vodyanitskii, 2010; Niedźwiecka et al, 2017; Yan et al, 2018; Yuan et al, 2018). Many studies have documented that Fe(II) oxidation is closely associated with the fate of heavy metals in anoxic environments (Vodyanitskii, 2010).…”

Biotransformation and photolysis of 2,4-dinitroanisole, 3-nitro-1,2,4-triazol-5-one, and nitroguanidine

“…68 Iron coupled to electron shuttling organisms has been demonstrated to reduce DNAN. 69 Finally, zero-valent iron was used to reduce DNAN waste before Fenton's oxidation and polishing with a biological treatment scheme. 70 DNAN reduction products can be oxidized by manganese oxides and DNAN can be reduced by various iron redox systems.…”