Microwaves make a quick meal of chemical weapons & pesticides

C&I Issue 17, 2008

Researchers have developed a simple, cheap and effective way to quickly render chemical weapons and pesticides safe using a kitchen microwave. Degradation of these compounds in the microwave achieved in minutes what would normally take 10h of thermal reflux at 140ºC, according to researchers at US firm Ashwin-Ushas that came up with the method.

It should also be much cheaper as it requires less energy to break the chemicals down and the hydrolysate produced by the process does not require costly incineration. With both Russia and the US signed up to a convention to destroy their chemical weapons stockpiles by 2012, it could dramatically speed up disposal.

To test out their idea, researchers first rendered molecules that closely simulate chemical weapon agents, like VX, safe by hydrolysing them. Nerve agent substitutes, such as dimethyl methylphosphonate (DMMP), were dissolved in an acidic phosphate medium. The mixture was then microwaved in an ordinary 700W microwave for up to 18 minutes. Calcium oxide was added to neutralise the solution and precipitate out the hydrolysed nerve agent simulants.

More than 99% of the nerve agent substitutes were destroyed by this process. One explanation for why microwaving breaks down these kinds of chemicals much faster than heat alone is that microwaves are constantly activating the chemicals, explains Ashwin-Ushas’ Prasann Chandrasekhar. ‘The [nerve agent simulants] can be precipitated out as a harmless inorganic phosphate that can go to landfill,’ he explains.

The method should also be equally applicable to pesticides, some of which are not too dissimilar in structure to nerve agents.

Ashwin-Ushas now plans to adapt the process to deal with solid waste, such as gloves, masks and metallic components contaminated with either nerve agents or pesticides. Surprisingly, Chandrasekhar says, the restrictions on disposing of waste contaminated with domestic pesticides in the US are minimal. ‘When [the pesticide] is in the concentrated form, say on gloves, it really shouldn’t be going into waste landfill.’

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