Contact: Lauren Ward
412-268-7761
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For immediate release:
September 10, 2003
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Backgrounder: TetraAmidoMacrocyclicLigand (TAML®) Complexes
Researchers at the Institute for Green Oxidation Chemistry at Carnegie Mellon University have developed an environmentally friendly, or “green,” method for breaking down dangerous compounds quickly and efficiently. Led by Terry Collins, the team set out to design a suite of catalysts that activate hydrogen peroxide. These innovative catalysts could be used to remove dye in wastewater from textile manufacturing, reduce fuel pollutants, treat pulp and paper processing byproducts, detoxify pesticides, and clean up hazardous biological materials.
The goal of the institute is to redefine oxidation chemistry in particular and chemistry in general to make chemical processes greener. This driving principle led Collins and his team to develop Fe-TAML activators.
What is Fe-TAML?
Fe-TAML consists of an atom of iron surrounded by the TAML ligand, which is composed of carbon, hydrogen, nitrogen and oxygen groups. Fe-TAML is a catalyst that works in combination with hydrogen peroxide (H2O2) to convert harmful pollutants into less toxic or harmless substances. A catalyst is a substance that is added to a chemical reaction to speed up the process and that is not changed or consumed by the overall reaction.
How do Fe-TAMLs work?
Fe-TAML binds to an oxygen atom in hydrogen peroxide to form a reactive intermediate. The intermediate then reacts with a pollutant to make it less toxic or harmless via a chemical process called oxidation. This process may be simple or involve multiple chemical reactions. This is very much dependent on the target molecule.
The Fe-TAML/hydrogen peroxide combination offers a promising cleanup technology for industries such as paper and wood pulp manufacturing. The use of a chlorine-based bleaching process in this industry produces hazardous chlorinated byproducts and recalcitrant color, which in turn clouds natural waterways. Fe-TAML activators are useful in detoxifying the chlorinated byproducts and in removing color from mill wastewater. Fe-TAML activators may one day replace chlorine-based bleaching processes, thereby averting the formation of chlorinated byproducts and greatly reducing or eliminating color production associated with paper processing.
Why use Fe-TAML?
After Collins and his team designed the Fe-TAMLs, they began testing and modifying them to create a catalyst that is:
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Environmentally friendly |
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Non-toxic |
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Easily and inexpensively produced in bulk |
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Able to work in ambient conditions – room temperature, normal pressure and a neutral pH |
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Very selective – to allow the reaction to work against very specific compounds, so that it would not initiate unintended reactions. |
Fe-TAMLs activate one of nature’s two principal oxidizing agents, hydrogen peroxide, to give alternatives to chlorine-based technologies and create totally new oxidation processes. They are water-soluble and easy to use; in addition, they also work over broad pH range and work well at the temperatures commonly encountered in a given chemical process.
Although they are highly selective, their synthesis is straightforward. Fe-TAMLs are “dial-a-lifetime” catalysts. They have a lifespan that can range from seconds to several hours, or even days. A Fe-TAML can be chosen such that it will perform the desired task and then destroy itself—a factor that is very important to the original green design idea.
Fe-TAML R&D
The overriding goal of the institute is to develop a technology that will purify drinking water. To this end, extensive laboratory and field tests have been conducted on processes that clean wastewater from textile manufacturing, treat pulp and paper processing byproducts, and purify water.
Laboratory testing conducted by Collins’ team found Fe-TAMLs have the potential to effectively detoxify pesticides, chemical warfare agents and simulants of biological warfare agents, such as anthrax. Additional laboratory testing has been conducted showing that Fe-TAMLs reduce fuel pollutants.
The Collins’ group has shown that Fe-TAMLs can work with oxygen in addition to hydrogen peroxide, thereby extending the range of applications made possible through the use of Fe-TAML. There are still many more application areas to be explored with the Fe-TAML family of compounds.
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