Polysaccharide-Thickened Aqueous Fluoride Solutions for Rapid Destruction of the Nerve Agent VX. Introducing the Opportunity for Extensive Decontamination Scenarios

Among the chemical warfare agents, the extremely toxic nerve agent VX (<i>O</i>-ethyl <i>S</i>-2-(diisopropylamino)­ethyl methylphosphonothioate) is a target of high importance in the development of decontamination methods, due to its indefinite persistence on common environmental surfaces. Liquid decontaminants are mostly characterized by high corrosivity, usually offer poor coverage, and tend to flow and accumulate in low areas. Therefore, the development of a noncorrosive decontaminant, sufficiently viscous to resist dripping from the contaminated surface, is necessary. In the present paper we studied different polysaccharides-thickened fluoride aqueous solutions as noncorrosive decontaminants for rapid and efficient VX degradation to the nontoxic product EMPA (ethyl methylphosphonic acid). Polysaccharides are environmentally benign, natural, and inexpensive. Other known decontaminants cannot be thickened by polysaccharides, due to the sensitivity of the latter toward basic or oxidizing agents. We found that the efficiency of VX degradation in these viscous solutions in terms of kinetics and product identity is similar to that of KF aqueous solutions. Guar gum (1.5 wt %) with 4 wt % KF was chosen for further evaluation. The benign nature, rheological properties, adhering capabilities to different surfaces, and decontamination from a porous matrix were examined. This formulation showed promising properties for implementation as a spray decontaminant for common and sensitive environmental surfaces

Solvent Effects on the Reactions of the Nerve Agent VX with KF/Al₂O₃: Heterogeneous or Homogeneous Decontamination?

Solvent effects on the reactions of the extremely toxic nerve agent VX with KF/Al₂O₃ powder were explored. Small quantities of water or methanol (5–10 wt %), which effectively mobilized all components while maintaining the heterogeneous nature of the reaction, promoted much faster rates than those obtained with larger quantities. Any amount of acetonitrile resulted in extremely slow transformations. Surprisingly, 5–50 wt % of heptane led to fast reactions due to the combination of its ability to mediate fast diffusion of VX and a MAS centrifugation effect

Hydrothermal Degradation of Chemical Warfare Agents on Activated Carbon: Rapid Chemical-Free Decontamination

Hydrothermal treatment of activated carbon contaminated with adsorbed HD, VX, or sarin at temperatures of 90–120 °C decomposes >95% of the adsorbed chemical warfare agents within a period of 0.5–4 h, in an environmentally friendly route that is free of corrosive chemicals and ends in nontoxic products

VX Fate on Common Matrices: Evaporation versus Degradation

A study of the volatilization rate of the nerve agent VX (<i>O</i>-ethyl <i>S</i>-2-(<i>N</i>,<i>N</i>-diisopropylamino)­ethyl methylphosphonothiolate) from various urban matrices in a specially designed climatic chamber (model system) is described. The performance of the model system combined with the analytical procedure produced profiles of vapor concentration obtained from samples of VX dispersed as small droplets on the surfaces of the matrices. The results indicated that the bitumen-containing surfaces such as asphalt blocks and bitumen sheets conserve VX and slow-release part of it over a long period of time. No complete mass balance could be obtained for these surfaces. Influence of environmental and experimental parameters as well as the efficacy of decontamination procedure were also measured. From smooth surface tiles a fast release of VX was measured and almost a complete mass balance was obtained, which characterizes the behavior of inert surfaces. Experiments carried out on concrete blocks showed fast decay of the concentration profile along with a very poor reconstruction of the initial quantity of VX, implying that this matrix degraded VX actively due to its multiple basic catalytic sites. To complement this study, solid-state NMR measurements were compared to add data concerning agent-fate within the matrices