TY - JOUR
T1 - Treatment of the insensitive munitions compound, 3-nitro-1,2,4-triazol-5-one (NTO), in flow-through columns packed with zero-valent iron
AU - Yu, Youngjae
AU - Root, Robert A.
AU - Sierra-Alvarez, Reyes
AU - Chorover, Jon
AU - Field, Jim A.
N1 - Publisher Copyright:
© 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2023/5
Y1 - 2023/5
N2 - The need for effective technologies to remediate the insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) is emerging due to the increasing use by the US Army and environmental concerns about the toxicity and aqueous mobility of NTO. Reductive treatment is essential for the complete degradation of NTO to environmentally safe products. The objective of this study is to investigate the feasibility of applying zero-valent iron (ZVI) in a continuous-flow packed bed reactor as an effective NTO remediation technology. The ZVI-packed columns treated an acidic influent (pH 3.0) or a circumneutral influent (pH 6.0) for 6 months (ca. 11,000 pore volumes, PVs). Both columns effectively reduced NTO to the amine product, 3-amino-1,2,4-triazol-5-one (ATO). The column treating the pH-3.0 influent exhibited prolonged longevity in reducing NTO, treating 11-fold more PVs than the column treating pH-6.0 influent until the breakthrough point (defined as when 85% of NTO was removed). The exhausted columns (defined as when only 10% of NTO was removed) regained the NTO reducing capacity by reactivation using 1 M HCl, fully removing NTO. After the experiment, solid-phase analysis of the packed-bed material showed that ZVI was oxidized to iron (oxyhydr)oxide minerals such as magnetite, lepidocrocite, and goethite during NTO treatment. This is the first report on the reduction of NTO and the concomitant oxidation of ZVI in continuous-flow column experiments. The evidence indicates that treatment in a ZVI-packed bed reactor is an effective approach for the removal of NTO. Graphical abstract: [Figure not available: see fulltext.]
AB - The need for effective technologies to remediate the insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) is emerging due to the increasing use by the US Army and environmental concerns about the toxicity and aqueous mobility of NTO. Reductive treatment is essential for the complete degradation of NTO to environmentally safe products. The objective of this study is to investigate the feasibility of applying zero-valent iron (ZVI) in a continuous-flow packed bed reactor as an effective NTO remediation technology. The ZVI-packed columns treated an acidic influent (pH 3.0) or a circumneutral influent (pH 6.0) for 6 months (ca. 11,000 pore volumes, PVs). Both columns effectively reduced NTO to the amine product, 3-amino-1,2,4-triazol-5-one (ATO). The column treating the pH-3.0 influent exhibited prolonged longevity in reducing NTO, treating 11-fold more PVs than the column treating pH-6.0 influent until the breakthrough point (defined as when 85% of NTO was removed). The exhausted columns (defined as when only 10% of NTO was removed) regained the NTO reducing capacity by reactivation using 1 M HCl, fully removing NTO. After the experiment, solid-phase analysis of the packed-bed material showed that ZVI was oxidized to iron (oxyhydr)oxide minerals such as magnetite, lepidocrocite, and goethite during NTO treatment. This is the first report on the reduction of NTO and the concomitant oxidation of ZVI in continuous-flow column experiments. The evidence indicates that treatment in a ZVI-packed bed reactor is an effective approach for the removal of NTO. Graphical abstract: [Figure not available: see fulltext.]
KW - Chemical degradation
KW - Groundwater remediation
KW - Iron oxidation
KW - NTO reduction
KW - Water treatment
KW - Zero-valent iron
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U2 - 10.1007/s11356-023-26922-5
DO - 10.1007/s11356-023-26922-5
M3 - Article
C2 - 37071366
AN - SCOPUS:85152961074
SN - 0944-1344
VL - 30
SP - 64606
EP - 64616
JO - Environmental Science and Pollution Research
JF - Environmental Science and Pollution Research
IS - 23
ER -