Presidential Green Chemistry Challenge: 1999 Academic Award
Professor Terry Collins of Carnegie Mellon University
TAMLTM Oxidant Activators: General Activation of Hydrogen Peroxide for Green Oxidation Technologies
Innovation and Benefits: Professor Collins developed a series of activator chemicals that work with hydrogen peroxide to replace chlorine bleaches. His TAMLTM activators have many potential uses that include preparing wood pulp for papermaking and removing stains from laundry. This novel, environmentally benign technology eliminates chlorinated byproducts from wastewater streams and saves both energy and water.
Summary of Technology: In nature, selectivity is achieved through complex mechanisms using a limited set of elements available in the environment. In the laboratory, chemists prefer a simpler design that utilizes the full range of the periodic table. The problem of persistent pollutants in the environment can be minimized by employing reagents and processes that mimic those found in nature. By developing a series of activators effective with the natural oxidant, hydrogen peroxide, Professor Terry Collins has devised an environmentally-benign oxidation technique with widespread applications. TAMLTM activators (tetraamido-macrocyclic ligand activators) are iron-based and contain no toxic functional groups. These activators offer significant technology breakthroughs in the pulp and paper industry and the laundry field.
The key to quality papermaking is the selective removal of lignin from the white fibrous polysaccharides, cellulose and hemicellulose. Wood pulp delignification has traditionally relied on chlorine-based processes that produce chlorinated pollutants. Professor Collins has demonstrated that TAMLTM activators effectively catalyze hydrogen peroxide in the selective delignification of wood pulp. This is the first low-temperature peroxide oxidation technique for treating wood pulp, which translates to energy savings for the industry. Environmental compliance costs may be expected to decrease with this new approach because chlorinated organics are not generated in this totally chlorine-free process.
TAMLTM activators may also be applied to the laundry field, where most bleaches are based on peroxide. When bound to fabric, most commercial dyes are unaffected by the TAMLTM-activated peroxide. However, random dye molecules that "escape" the fabric during laundering are intercepted and destroyed by the activated peroxide before they have a chance to transfer to other articles of clothing. This technology prevents dye-transfer accidents while offering improved stain-removal capabilities. Washing machines that require less water will be practical when the possibility of dye-transfer is eliminated.
An active area of investigation is the use of TAMLTM peroxide activators for water disinfection. Ideally, the activators would first kill pathogens in the water sample, then destroy themselves in the presence of a small excess of peroxide. This protocol could have global applications, from developing nations to individual households.
The versatility of the TAMLTM activators in catalyzing peroxide has been demonstrated in the pulp and paper and laundry industries. Environmental benefits include decreased energy requirements, elimination of chlorinated organics from the waste stream, and decreased water use. The development of new activators and new technologies will provide environmental advantages in future applications.
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