Does Concrete Self-Decontaminate VX; Conference paper

摘要

A preliminary study has been done to examine the sorption and reaction of VX in an aged sample of concrete using P31 NMR. Facile sorption of neat liquid VX into concrete is observed. The half-life for this process is about 2 min, and is attributed to VX penetrating the surface pores to form a sorbed phase tentatively assigned to a solid protonated form of VX. Once sorbed, the VX slowly hydrolyzes to non-toxic ethyl methylphosphonic acid (EMPA) with a half-life of about 3 months. Closer examination of the reaction of neat liquid VX with crushed concrete reveals a two-step behavior in the kinetics. An initial reaction with a half-life of about 2 h consumes 12% of the VX. After about 1 h, a much slower steady state hydrolysis ensues exhibiting a half-life of 28 days. EMPA is the sole hydrolysis product detected in the P31 MAS NMR spectra; no toxic EA-2192 is observed. Considering the concrete surface area, one monolayer would accommodate 13% of the applied VX. Thus the observed kinetic behavior is consistent with the concrete surface possessing a limited reactive capacity corresponding to about one VX monolayer.