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Green catalyst destroys pesticides and munitions toxins

29.08.2005

Results reported at American Chemical Society meeting

A chemical catalyst developed at Carnegie Mellon University completely destroys dangerous nitrophenols in laboratory tests, according to Arani Chanda, a doctoral student who is presenting his findings on Sunday, Aug. 28, at the 230th meeting of the American Chemical Society (ACS) in Washington, D.C. (Division of Industrial and Engineering Chemistry, Convention Center Hall A).

"We found an efficient, rapid and environmentally friendly means of completely destroying these compounds," said Chanda, who works in the laboratory of Terrence Collins, the Thomas Lord Professor of Chemistry and director of the Institute for Green Oxidation Chemistry at the Mellon College of Science (MCS) at Carnegie Mellon.

Nitrophenols are man-made pollutants that mostly originate from wastewater discharges from the dye, pesticide and ammunition industries as well as from various chemical-manufacturing plants. They are also found in diesel exhaust particles. Thousands of tons of these agents are produced yearly by countries around the world. Registered as priority pollutants by the EPA, they are toxic to aquatic life. They produce immediate toxic effects to the nervous system, and some reports have implicated them as possible endocrine disruptors. Many of these compounds cannot be destroyed by existing means.

The catalyst, one of a family of catalysts called Fe-TAML®s (TAML stands for tetra-amido macrocyclic ligand), works with hydrogen peroxide. Its "green" design is based on elements used naturally in biochemistry. Fe-TAMLs were discovered by Collins, whose group has developed an extensive suite of these catalysts to provide clean, safe alternatives to existing industrial practices, as well as ways to remediate other pressing problems that currently lack solutions.

"Fe-TAMLs are much easier to use in destroying nitrophenols because they work at ambient temperatures and neutral pH," said Collins. "Existing detoxification methods are inefficient and work only under acidic conductions. Our method can be used over a much broader pH range, including wastewater pH conditions."

Fe-TAMLs already have shown promise in killing a simulant of a biological warfare agent (anthrax), reducing fuel pollutants, treating pulp and paper processing byproducts, and detoxifying pesticides. A major goal is to develop Fe-TAMLs as a safe, cost-effective means of global water decontamination.

Collins and other members of his laboratory are presenting additional findings about Fe-TAMLs during these sessions at the 230th ACS meeting:

"TAML green oxidation catalysis for safely destroying pollutants and microbes in water," oral presentation by Terrence Collins, INOR 265, Strategies and Molecular Mechanisms of Contaminant Degradation Chemistry, 2 p.m. Monday, Aug. 29, Convention Center 147B;

"Micellar regulation of the activity of Fe-TAML® activators of peroxides in aqueous solutions," poster presentation by Deboshri Banerjee, I&EC 11, 8 p.m. Sunday, Aug. 28, Convention Center, Hall A.