Friday, October 10, 2003
Fe-TAML® Activators Developed at Carnegie Mellon Break Down Toxic Pesticides
NEW YORK—Carnegie Mellon University scientists have found that a rapid, environmentally friendly catalytic process involving Fe-TAML® activators and hydrogen peroxide appears to totally break down some organophosphorus compounds, a widely used class of agricultural pesticides associated with profound toxicity.
The results of preliminary laboratory studies are being presented by Arani Chanda, a Carnegie Mellon graduate student, on Wednesday, Sept. 10, in New York City at the 226th annual meeting of the American Chemical Society (paper 162, “Total degradation of organophosphorus compounds using Fe-TAML® activators of peroxide,” Industrial & Engineering Chemistry Division).
“These early results show that Fe-TAML activators are capable of breaking down some of the most harmful compounds that leach into our water supply,” said Terry Collins, director of the Institute for Green Oxidation Chemistry at Carnegie Mellon and the Thomas Lord Professor of Chemistry at the Mellon College of Science (MCS).
Although effective at curbing insect damage to crops, some organophosphorus compounds have been associated with neurotoxicity and other health problems. Because organophosphorus compounds have a range of chemical structures, the Collins team is establishing the best methodologies to use Fe-TAML activators to decompose them into benign byproducts.
The Fe-TAML (TAML stands for tetra-amido macrocyclic ligand) activators are synthetic catalysts made with elements found in nature.
Currently, there are no commercial technologies to destroy organophosphorus compounds spread in agricultural settings. These chemicals break down naturally only over a long time period and can leave toxic byproducts. Theoretically, small amounts of Fe-TAML activators with hydrogen peroxide, or perhaps oxygen, as the oxidant could be spread on fields after a crop harvest to reduce the entry of the pesticides into the groundwater, as well as nearby streams and estuaries. Once they are commercially available, Fe-TAML activators could provide the best available technology for decontaminating large stocks of expired pesticides around the world, according to Collins.
The Collins group already has published extensively (see April 12, 2002 issue of Science) on the use of very small concentrations of Fe-TAML activators and hydrogen peroxide to rapidly and safely break down pentachlorophenol and 2,4,6 trichlorophenol in water at room temperature. These chemicals belong to another major class of compounds, chlorophenols, which are found in pesticides, disinfectants, wood preservatives and other products. Some of these compounds are federally regulated, given their inherent persistence, their inherent toxicity and their propensity to decay under natural oxidizing conditions into long-lived dioxins. Dioxins accumulate in tissues of animals and are linked with a variety of ailments, including cancer.
Further laboratory research is needed, according to Collins, before the Fe-TAML activators and hydrogen peroxide could be deployed in field testing for pesticide degradation.
Fe-TAML activators originated at Carnegie Mellon’s Institute for Green Oxidation Chemistry under the leadership of Collins, a strong proponent of green chemistry to create environmentally friendly, sustainable technologies. Fe-TAML activators show enormous potential to provide clean, safe alternatives to existing industrial practices. They also provide ways to remediate other pressing problems that currently lack solutions. The pesticide degradation research was supported partially by the Eden Hall Foundation of Pittsburgh.
As part of this September’s American Chemical Society meeting symposium, “Green Chemistry: Multidisciplinary Science and Engineering Applied to Global Environmental Issues,” the Collins group will present results of Fe-TAML activators’ effectiveness in killing a simulant of a biological warfare agent, reducing fuel pollutants, treating pulp and paper processing byproducts, and removing dye from textile mill effluent. At the symposium, the Collins group also will highlight how Fe-TAML activators can work with oxygen rather than hydrogen peroxide, thereby extending tremendously the range of potential applications of these catalysts.
By: Lauren Ward