A synergistic nanoscale zero valent iron-hydrogen peroxide technology for treatment of insensitive munitions wastewaters
Date
2021
Authors
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Publisher
University of Delaware
Abstract
The U.S. Army is phasing out legacy munitions compounds that are prone to accidental detonation and replacing them with insensitive munitions compounds (IMCs). The major IMCs, namely 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and nitroguanidine (NQ), are not compatible with existing munitions wastewater treatment technologies such as granular activated carbon due to their high water solubilities. In this study, a two-stage process employing nanoscale zero-valent iron (nZVI) and hydrogen peroxide (H2O2) was evaluated as a potential technology for destructive treatment of IMC wastewater. In the first stage, nZVI rapidly and completely degraded all three IMCs and generated dissolved Fe(II). NTO and DNAN were degraded via nitro reduction to 3-amino-1,2,4-triazol-5-one and 2,4-diaminoanisole, respectively. In the second stage, H2O2 was added to oxidize the IMC reduction products through Fenton reaction. nZVI-treated NTO and DNAN samples showed 66% and 63% TOC removal, respectively, after oxidation. In contrast, NQ reduction products exhibited negligible mineralization. The results with individual IMCs were confirmed through an experiment using a synthetic wastewater containing all three IMCs (TOC = 42 mg/L per IMC). Furthermore, a 50-fold scale-up of the reactor size and volume in a pilot study to demonstrate the use of the technology at military facilities showed results consistent with those at smaller scales. This study illustrates the potential feasibility of an nZVI–H2O2 technology for treating IMC-ladened wastewaters at military facilities.
Description
Keywords
Fenton oxidation, Insensitive munitions compounds, Mineralization, Nano-zerovalent iron, Reduction, Wastewater treatment