Abiotic transformation of high explosives by freshly precipitated iron minerals in aqueous FeII solutions

Hardiljeet K. Boparai, Steve D. Comfort, Tunlawit Satapanajaru, Jim E. Szecsody, Paul R. Grossl, Patrick J. Shea

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Zerovalent iron barriers have become a viable treatment for field-scale cleanup of various ground water contaminants. While contact with the iron surface is important for contaminant destruction, the interstitial pore water within and near the iron barrier will be laden with aqueous, adsorbed and precipitated FeII phases. These freshly precipitated iron minerals could play an important role in transforming high explosives (HE). Our objective was to determine the transformation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and TNT (2,4,6-trinitrotoluene) by freshly precipitated iron FeII/FeIII minerals. This was accomplished by quantifying the effects of initial FeII concentration, pH, and the presence of aquifer solids (FeIII phases) on HE transformation rates. Results showed that at pH 8.2, freshly precipitated iron minerals transformed RDX, HMX, and TNT with reaction rates increasing with increasing FeII concentrations. RDX and HMX transformations in these solutions also increased with increasing pH (5.8-8.55). By contrast, TNT transformation was not influenced by pH (6.85-8.55) except at pH values <6.35. Transformations observed via LC/MS included a variety of nitroso products (RDX, HMX) and amino degradation products (TNT). XRD analysis identified green rust and magnetite as the dominant iron solid phases that precipitated from the aqueous FeII during HE treatment under anaerobic conditions. Geochemical modeling also predicted FeII activity would likely be controlled by green rust and magnetite. These results illustrate the important role freshly precipitated FeII/FeIII minerals in aqueous FeII solutions play in the transformation of high explosives.

Original languageEnglish (US)
Pages (from-to)865-872
Number of pages8
JournalChemosphere
Volume79
Issue number8
DOIs
StatePublished - May 1 2010

Fingerprint

Minerals
explosive
Trinitrotoluene
Iron
aqueous solution
HMX
trinitrotoluene
iron
mineral
Ferrosoferric Oxide
rust disease
Groundwater
Magnetite
magnetite
porewater
Impurities
pollutant
triazine
cleanup
Aquifers

Keywords

  • Green rust
  • HMX
  • High explosives
  • Magnetite
  • RDX
  • TNT

ASJC Scopus subject areas

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

Cite this

Abiotic transformation of high explosives by freshly precipitated iron minerals in aqueous FeII solutions. / Boparai, Hardiljeet K.; Comfort, Steve D.; Satapanajaru, Tunlawit; Szecsody, Jim E.; Grossl, Paul R.; Shea, Patrick J.

In: Chemosphere, Vol. 79, No. 8, 01.05.2010, p. 865-872.

Research output: Contribution to journalArticle

Boparai, Hardiljeet K. ; Comfort, Steve D. ; Satapanajaru, Tunlawit ; Szecsody, Jim E. ; Grossl, Paul R. ; Shea, Patrick J. / Abiotic transformation of high explosives by freshly precipitated iron minerals in aqueous FeII solutions. In: Chemosphere. 2010 ; Vol. 79, No. 8. pp. 865-872.
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AU - Comfort, Steve D.

AU - Satapanajaru, Tunlawit

AU - Szecsody, Jim E.

AU - Grossl, Paul R.

AU - Shea, Patrick J.

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AB - Zerovalent iron barriers have become a viable treatment for field-scale cleanup of various ground water contaminants. While contact with the iron surface is important for contaminant destruction, the interstitial pore water within and near the iron barrier will be laden with aqueous, adsorbed and precipitated FeII phases. These freshly precipitated iron minerals could play an important role in transforming high explosives (HE). Our objective was to determine the transformation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and TNT (2,4,6-trinitrotoluene) by freshly precipitated iron FeII/FeIII minerals. This was accomplished by quantifying the effects of initial FeII concentration, pH, and the presence of aquifer solids (FeIII phases) on HE transformation rates. Results showed that at pH 8.2, freshly precipitated iron minerals transformed RDX, HMX, and TNT with reaction rates increasing with increasing FeII concentrations. RDX and HMX transformations in these solutions also increased with increasing pH (5.8-8.55). By contrast, TNT transformation was not influenced by pH (6.85-8.55) except at pH values <6.35. Transformations observed via LC/MS included a variety of nitroso products (RDX, HMX) and amino degradation products (TNT). XRD analysis identified green rust and magnetite as the dominant iron solid phases that precipitated from the aqueous FeII during HE treatment under anaerobic conditions. Geochemical modeling also predicted FeII activity would likely be controlled by green rust and magnetite. These results illustrate the important role freshly precipitated FeII/FeIII minerals in aqueous FeII solutions play in the transformation of high explosives.

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