Researchers discover new treatment for pesticides
2nd March 2004
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| David Sedlak and Sung Hee Joo |
Researchers from civil and environmental engineering have discovered a simple chemical process, based on a rust-like action, which could revolutionise the treatment of pesticides and contaminated water.
The reaction, which involves the corrosion of nano-sized particles of iron in water, could be used to treat pesticides, industrial chemicals and purify contaminated water for domestic use.
In 2002, graduate student Sung Hee Joo was working with nano-sized particles of zero-valent iron (ZVI), which are highly reactive.
When she put the ZVI into water with the commonly used herbicide molinate, she discovered that the oxygen in the water corroded the iron, a very powerful oxidising agent was produced and it broke down the pesticide.
The discovery flew in the face of accepted wisdom about the action of iron in breaking down pesticides. Although there has been a lot of work done in this area internationally, it was thought that the reactive process was reductive. No other researcher anywhere in the world had previously shown that the mechanism of ZVI was oxidative.
The results of Joo’s work has just been published in a paper co-authored by Professor David Waite and Dr Andrew Feitz, in the journal Environmental Science and Technology.
“[Joo’s discovery] was surprising,” said Fulbright fellow in civil and environmental engineering, Professor David Sedlak. “People knew that iron had the potential to transform organic compounds, but the kinds of reactions that people had observed before were selective reactions. Nobody had ever seen an oxidative reaction where the organic compound [was completely] oxidised.”
Other researchers had previously only used commercially-available granular iron particles. “It was known that organics could be treated using granular ZVI, but not in the presence of oxygen, so this was a totally different theory,” Joo said.
There are wide-ranging possible applications of the discovery. “The relative simplicity of this technique and the availability of key reactants suggest that this method could be widely used to degrade agrochemical contaminants and contaminants in water treatment,” she said.
It could also complement biodegradation of contaminated water – when naturally-occurring bacteria and the action of filtration through the soil purifies contaminated water.
Joo is now working with Sedlak, Waite and Feitz investigating the reaction further, to understand the exact mechanism by which the pesticide was degraded.
The reaction, which involves the corrosion of nano-sized particles of iron in water, could be used to treat pesticides, industrial chemicals and purify contaminated water for domestic use.
In 2002, graduate student Sung Hee Joo was working with nano-sized particles of zero-valent iron (ZVI), which are highly reactive.
When she put the ZVI into water with the commonly used herbicide molinate, she discovered that the oxygen in the water corroded the iron, a very powerful oxidising agent was produced and it broke down the pesticide.
The discovery flew in the face of accepted wisdom about the action of iron in breaking down pesticides. Although there has been a lot of work done in this area internationally, it was thought that the reactive process was reductive. No other researcher anywhere in the world had previously shown that the mechanism of ZVI was oxidative.
The results of Joo’s work has just been published in a paper co-authored by Professor David Waite and Dr Andrew Feitz, in the journal Environmental Science and Technology.
“[Joo’s discovery] was surprising,” said Fulbright fellow in civil and environmental engineering, Professor David Sedlak. “People knew that iron had the potential to transform organic compounds, but the kinds of reactions that people had observed before were selective reactions. Nobody had ever seen an oxidative reaction where the organic compound [was completely] oxidised.”
Other researchers had previously only used commercially-available granular iron particles. “It was known that organics could be treated using granular ZVI, but not in the presence of oxygen, so this was a totally different theory,” Joo said.
There are wide-ranging possible applications of the discovery. “The relative simplicity of this technique and the availability of key reactants suggest that this method could be widely used to degrade agrochemical contaminants and contaminants in water treatment,” she said.
It could also complement biodegradation of contaminated water – when naturally-occurring bacteria and the action of filtration through the soil purifies contaminated water.
Joo is now working with Sedlak, Waite and Feitz investigating the reaction further, to understand the exact mechanism by which the pesticide was degraded.
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