Volcanic mineral and sunlight break down pesticides

A team of chemists from the University of Maine have found that by exposing pesticide-contaminated water to natural light and a volcanic mineral they can rapidly speed up the breakdown of the pesticides.

Zeolites, which are already used in products such as cat litter, shoe deodorisers, and aquarium filters, have a honeycomb structure which allows them to absorb other materials much like a sponge absorbs water, enabling light to disrupt chemical bonds, say the researchers. The team tested a variety of insecticides commonly detected in rivers and drinking waters, including malathion which is known to kill lobsters and is used to control the spread of West Nile virus by mosquitoes. According to the researchers, the decomposition process showed “astonishing increases in the rate of each reaction” when the zeolite was present.

“It’s important to find the zeolite with the right size channels and surface chemistry,” said Howard H. Patterson, Professor of Chemistry at the University of Maine. “You want it tailored to the size of the molecule that you want to break down. A pesticide molecule enters a zeolite channel and fits snugly like a hand in a glove. When you expose it to light, a reaction occurs, and the pesticide molecule breaks apart.”

The reaction rates for malathion, carbofuran and carbaryl were 35, 120 and 164 times faster respectively than the rates for those compounds when the zeolite was not present.

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