Remediating RDX-Contaminated Water and Soil Using Zero-Valent Iron
- J. Singh,
- S. D. Comfort * and
- P. J. Shea
Soil and water contaminated with RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) pose a serious threat to the environment and human health. Our objective was to determine the potential for using zero-valent iron (Fe0) to remediate RDX-contaminated water and soil. Mixing an aqueous solution of 32 mg RDX L−1 (spiked with 14C-labeled RDX) with 10 g Fe0 L−1 resulted in complete RDX destruction within 72 h. Nitroso derivatives of RDX accounted for approximately 26% of the RDX transformed during the first 24 h; these intermediates disappeared within 96 h and the remaining 14C products were water soluble and not strongly sorbed by iron surfaces. When RDX-contaminated soil (30 mg RDX kg−1 spiked with 14C-RDX) was treated with a single amendment of Fe0 (20 g kg−1 soil) in a static soil microcosm, more than 60% of the initial 14C-RDX was recovered as 14CO2 after 112 d. Treating surface and subsurface soils containing 3600 mg RDX kg−1 with 50 g Fe0 kg−1 at a constant soil water content (0.35–0.40 kg H2O kg−1 soil) resulted in a 52% reduction in extractable RDX following 12 mo of static incubation. A second Fe0 addition at 12 mo further reduced the initial extractable RDX by 71% after 15 mo. These results support the use of zero-valent iron for in situ remediation of RDX-contaminated soil.
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