Cleaning up after nerve agents


31 March 2008

A new decontamination agent devised by US chemists can deactivate toxic chemicals such as nerve agents and pesticides - leaving only non-toxic, easily disposable by-products, according to research in the New Journal of Chemistry. The work could lead to cheaper and more effective cleanup of contaminated sites such as chemical weapons stockpiles.

Existing methods for destroying nerve agents, such as treatment with bleach, are limited. Nerve agents in chemical weapons are often found as chemical mixtures, and bleach reacts indiscriminately - even explosively - with many chemicals such as propellants.   It is also corrosive to other materials and surfaces.

Other approaches such as alkaline hydrolysis have several drawbacks, including low solubility and slow reaction rates. Furthermore some decontamination methods give by-products, such as thioic acids, which are almost as toxic as the original nerve agent.

Now David Atwood (University of Kentucky, Lexington, US), Daniel Williams (Kennesaw State University, US) and co-workers have developed a destruction method based on dealkylating agents. Organophosphate-based nerve agents and pesticides can now be cleaved in a single reaction.

"This research demonstrates the first technique whereby nerve agents or pesticides can be made inactive in a direct reaction. The resulting non-toxic byproducts would be solids that could be easily handled or disposed of," explains Atwood. Looking to the future, "the technology could also be used to decontaminate vehicles or other objects that have been exposed to nerve agents", he adds.

The dealkylating agents are based on Schiff bases containing boron or aluminium and specifically cleave the phosphate ester bond in nerve agents or pesticides, preventing unwanted side reactions and surface corrosion.

"The search for a non-corrosive decontamination of sensitive material and skin after exposure by toxic chemicals, for example pesticides and nerve agents, is an important but challenging task," says Franz Worek, an expert in organophosphate toxicology at the Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany. "This new and promising approach may ultimately lead to a new type of mild and effective decontamination," he adds.

References

Amitabha Mitra, New J. Chem., 2008, DOI:  10.1039/b717041f

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