Adsorption and oxidation of 3-nitro-1,2,4-triazole-5-one (NTO) and its transformation product (3-amino-1,2,4-triazole-5-one, ATO) at ferrihydrite and birnessite surfaces.
Environ Pollut
; 240: 200-208, 2018 Sep.
Article
em En
| MEDLINE
| ID: mdl-29738948
ABSTRACT
The emerging insensitive munitions compound (IMC) 3-nitro-1,2,4-triazole-5-one (NTO) is currently being used to replace conventional explosives such as 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but the environmental fate of this increasingly widespread IMC remains poorly understood. Upon release from unexploded solid phase ordinances, NTO exhibits high aqueous solubility and, hence, potential mobilization to groundwater. Adsorption and abiotic transformation at metal oxide surfaces are possible mechanisms for natural attenuation. Here, the reactions at ferrihydrite and birnessite surfaces of NTO and its biotransformation product, 3-amino-1, 2, 4-triazol-5-one (ATO), were studied in stirred batch reactor systems at controlled pH (7.0). The study was carried out at metal oxide solid to solution ratios (SSR) of 0.15, 1.5 and 15â¯gâ¯kg-1. The samples were collected at various time intervals up to 3â¯h after reaction initiation, and analyzed using HPLC with photodiode array and mass spectrometric detection. We found no detectable adsorption or transformation of NTO upon reaction with birnessite, whereas ATO was highly susceptible to oxidation by the same mineral, showing nearly complete transformation within 5â¯minâ¯at 15â¯gâ¯kg-1 SSR to urea, CO2(g) and N2(g). The mean surface-area-normalized pseudo-first order rate constant (k) for ATO oxidation by birnessite across all SSRs was 0.05⯱â¯0.022â¯h-1â¯m-2, and oxidation kinetics were independent of dissolved O2 concentration. Both NTO and ATO were resistant to oxidation by ferrihydrite. However, NTO showed partial removal from solution upon reaction with ferrihydrite at 0.15 and 1.5â¯gâ¯kg-1 SSR and complete loss at 15â¯gâ¯kg-1 SSR due to strong adsorption. Conversely, ATO adsorption to ferrihydrite was much weaker than that measured for NTO.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Triazóis
/
Substâncias Explosivas
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Modelos Químicos
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Nitrocompostos
Idioma:
En
Revista:
Environ Pollut
Ano de publicação:
2018
Tipo de documento:
Article