Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one: Emerging munitions compounds

Julie B. Becher, Samuel A. Beal, Susan Taylor, Katerina M Dontsova, Dean E. Wilcox

Research output: Contribution to journalArticle

Abstract

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. Here, we irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths (254 nm, 300 nm, and 350 nm) and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were ≥80% for all three wavelengths, and consisted of large amounts of guanidine, nitrate, and nitrite, and smaller amounts of cyanamide, cyanoguanidine, urea, and ammonium. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h, with the major aqueous products identified as ammonium, nitrate, nitrite, and a urazole intermediate. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

Original languageEnglish (US)
Pages (from-to)418-426
Number of pages9
JournalChemosphere
Volume228
DOIs
StatePublished - Aug 1 2019

Fingerprint

Degradation
Nitrites
Wavelength
Nitrates
wavelength
Cyanamide
degradation
nitrite
Recovery
Water
Guanidine
Photodegradation
Ammonium Compounds
Urea
photodegradation
ammonium nitrate
half life
urea
Mathematical transformations
transform

Keywords

  • 3-nitro-1,2,4-triazol-5-one (NTO)
  • Nitroguanidine (NQ)
  • Transformation pathways
  • Transformation products
  • UV irradiation

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

Cite this

Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : Emerging munitions compounds. / Becher, Julie B.; Beal, Samuel A.; Taylor, Susan; Dontsova, Katerina M; Wilcox, Dean E.

In: Chemosphere, Vol. 228, 01.08.2019, p. 418-426.

Research output: Contribution to journalArticle

Becher, Julie B. ; Beal, Samuel A. ; Taylor, Susan ; Dontsova, Katerina M ; Wilcox, Dean E. / Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : Emerging munitions compounds. In: Chemosphere. 2019 ; Vol. 228. pp. 418-426.
@article{fc9fdb95f5d1423fa3062218a9a844c3,
title = "Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one: Emerging munitions compounds",
abstract = "Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. Here, we irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths (254 nm, 300 nm, and 350 nm) and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10{\%} degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were ≥80{\%} for all three wavelengths, and consisted of large amounts of guanidine, nitrate, and nitrite, and smaller amounts of cyanamide, cyanoguanidine, urea, and ammonium. NTO degradation was greatest at 300 nm with 3{\%} remaining after 32 h, followed by 254 nm (7{\%} remaining) and 350 nm (20{\%} remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48{\%} by 32 h, with the major aqueous products identified as ammonium, nitrate, nitrite, and a urazole intermediate. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.",
keywords = "3-nitro-1,2,4-triazol-5-one (NTO), Nitroguanidine (NQ), Transformation pathways, Transformation products, UV irradiation",
author = "Becher, {Julie B.} and Beal, {Samuel A.} and Susan Taylor and Dontsova, {Katerina M} and Wilcox, {Dean E.}",
year = "2019",
month = "8",
day = "1",
doi = "10.1016/j.chemosphere.2019.04.131",
language = "English (US)",
volume = "228",
pages = "418--426",
journal = "Chemosphere",
issn = "0045-6535",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one

T2 - Emerging munitions compounds

AU - Becher, Julie B.

AU - Beal, Samuel A.

AU - Taylor, Susan

AU - Dontsova, Katerina M

AU - Wilcox, Dean E.

PY - 2019/8/1

Y1 - 2019/8/1

N2 - Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. Here, we irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths (254 nm, 300 nm, and 350 nm) and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were ≥80% for all three wavelengths, and consisted of large amounts of guanidine, nitrate, and nitrite, and smaller amounts of cyanamide, cyanoguanidine, urea, and ammonium. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h, with the major aqueous products identified as ammonium, nitrate, nitrite, and a urazole intermediate. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

AB - Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. Here, we irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths (254 nm, 300 nm, and 350 nm) and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were ≥80% for all three wavelengths, and consisted of large amounts of guanidine, nitrate, and nitrite, and smaller amounts of cyanamide, cyanoguanidine, urea, and ammonium. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h, with the major aqueous products identified as ammonium, nitrate, nitrite, and a urazole intermediate. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

KW - 3-nitro-1,2,4-triazol-5-one (NTO)

KW - Nitroguanidine (NQ)

KW - Transformation pathways

KW - Transformation products

KW - UV irradiation

UR - http://www.scopus.com/inward/record.url?scp=85064905704&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85064905704&partnerID=8YFLogxK

U2 - 10.1016/j.chemosphere.2019.04.131

DO - 10.1016/j.chemosphere.2019.04.131

M3 - Article

C2 - 31051343

AN - SCOPUS:85064905704

VL - 228

SP - 418

EP - 426

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

ER -