Diffusion and Flux of Explosive-Related Compounds in Plastic Mine Surrogates
Abstract
Canine detection of buried land mines is thought to be an olfactory process and efforts are now underway to develop electronic sensing of explosives vapors. The quantity of these vapors is critical to any chemical-sensing-based procedure for detecting land mines. Plastic-cased mines release vapors of explosive-related compounds (ERC) by permeation through the casing as well as through holes and cracks. Measurement of permeation contributions to the release flux was reported previously for a few intact mines. Here we determine permeation-driven fluxes and diffusivities by analysis of ERC release into water as a function of time. The solubility of TNT and diffusivities of TNT, 2,4-DNT, and 1,3-DNB in five polymeric materials potentially used in mine casings are reported for the first time. This information can be used to estimate ERC fluxes from TNT-filled mines encased in any of these materials. Direct measurement of the release fluxes from intact mines are feasible and were described previously. Calculated diffusivities of the nitroaromatics in these materials were similar to those reported in the literature for other aromatic vapors. Diffusion was generally non-Fickian (concentration-dependent). TNT fluxes into Tedlar bags were also measured at 3, 13, and 22 degrees C for the five materials. The temperature dependence is well described by simple exponential relations of the van't Hoff/Arrhenius type, and an activation energy was calculated for the process. The temperature dependence of the fluxes was similar for all five materials. Fluxes of individual ERC components were also determined at 22 degrees C and reflected their abundance in the head space of the source explosive. Plastic/air partition coefficients of the contaminants ranged from 1 x 10(exp 3) to 3 X 10 (exp 3) and were about an order of magnitude higher for TNT than for DNB and were intermediate for DNT.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2003
- Accession Number
- ADA421294
Entities
People
- Daniel C. Leggett
- James H. Cragin
Organizations
- Engineer Research and Development Center