Effect of Drop Size on the Degradation of VX in Concrete
Abstract
The effect of drop size on the degradation rate of VX, O-ethyl S-[2-(diisopropylamino)ethyl]methylphosphonothioate, in fresh concrete has been examined using 31P NMR. Drops of neat VX, ranging in size from 4 micro-L to 0.2 micro-L, applied to small concrete coupons (8 mm x 15 mm) were observed to degrade at different rates, with the 1 micro-L and smaller drops reacting in less than 4 days, and the larger droplets reacting in less than 11 days. Additionally, 4 micro-L VX predissolved in hexane to evenly spread it over the concrete coupon likewise reacted faster, degrading in less than 5 days. The fresh concrete, less than 2 months old, exhibited significantly faster VX degradation for all drop sizes than that observed for "aged" concrete in a previous study where VX persisted for months. The enhanced reactivity of the "fresh" concrete for VX was maintained for at least a 1-year period. The pH of water containing crushed "fresh" and "aged" concrete was 10.0 and 9.0, respectively. The higher pH of the "fresh" concrete is one reason for its enhanced reactivity toward VX. An additional contribution to the enhanced reactivity of the "fresh" concrete is suggested by the increased mobility of its sorbed VX as evidenced by its significantly narrower peak in NMR spectra.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 24, 2004
- Accession Number
- ADA515759
Entities
People
- Carol A. Brevett
- George Wayne Wagner
- Jennifer L. Edwards
- Richard J. O'connor
Organizations
- Edgewood Chemical Biological Center