NON-TOXIC DRY CLEANING ALTERNATIVES
Water, despite its benign reputation, can wreak havoc on clothing -- as anyone who has ever ignored a "dry clean only" label can attest. Consequently, piles of clothing get lugged to the local dry cleaner, for fear of turning another silk dress into a rag or shrinking still more wool sweaters into garments for the family dog.Dry cleaning involves no water. Instead, clothes are treated for stains, then tumbled in perchloroethylene, a volatile, nonflammable organic liquid. Concerns that perchloroethylene -- or perc, as it's commonly known -- may be a human health hazard have inspired tighter controls on its use. Perc is regulated as an air pollutant under the Clean Air Act and constitutes an environmental contaminant when found in soil and water. Dry cleaners and other businesses that use perc must dispose of it as hazardous waste.
Stricter regulation is pushing researchers to find alternatives to perc and other polluting solvents (SN: 6/21/97, p. 391). Recently, a method designed to be less harmful to the environment has been developed. It uses detergents, steam, and precisely controlled temperatures.
Some scientists, though, are taking a different approach. They are dry cleaning with carbon dioxide, the compound that forms dry ice. No one disputes its safety. Carbon dioxide puts the fizz in soda pop, is exhaled in our breath, and is present as a small component of the air around us.
Dry cleaning technology using liquid carbon dioxide made its debut at a recent cleaners' trade show in Las Vegas. Soon, carbon dioxide may prove useful not only as a dry cleaning agent but also as a degreaser for industrial machinery and as an alternative solvent in a variety of manufacturing processes.
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Written by: Corinna Wu of Science News
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