TECHNOLOGY UPDATE CO2 gets taken to the cleaners The February opening of the first dry cleaning business employing liquid carbon dioxide marked the compound's first use as a commercial cleaning solvent. The new application joins a growing number of processes and products leveraging C02's extraordinary chemical versatility as a means to prevent pollution. Called Micare, the new dry cleaning process is the outgrowth of years of government-funded research into C02's possibilities as a solvent. It was transformed into a commercially viable process by Micell Technologies of Raleigh, N.C., in only three years. C0 2 is already being used as an alternative solvent for the decaffeination of coffee and as a nonozone-depleting paint propellant. Because the term "dry cleaning" was coined to denote the lack of water—not liquid—in the cleaning process, liquid C0 2 is a perfectly appropriate agent for dry cleaning, explained Micell chemist Chris Harbinson. All existing dry cleaning solvents are liquids, he added. like the industry's current cleaning mainstay, perchloroethylene—which is used by over 80% of the nation's 36,000-plus dry cleaners—the liquid C02 in Micell's Micare dry cleaning process excels at removing what are known in the business as "oil side" stains and grime, things like grease and the fatty acids on human skin. Harbinson calls the C0 2 a "carrier" for the soapy surfactants that stabilize the small amount of water used in the process to expel "wet side" stains such as sweat, wine, and pancake syrup. Although the company is very secretive about its proprietary detergents and surfactants, James DeYoung, Micell's research director, allowed that the process involves emulsifying the water in order to combine it with the C02 solvent. Conventional dry cleaning solvents require heat to effect wet side
cleaning. The fact that C0 2 can be made to mix with water at room temperature is to Micell's advantage, De Young said. Heat can both set stains and add to fabric wear and tear, he explained. The basic chemistry underlying the Micare process harks back to work that Joseph DeSimone, a chemistry professor at University North Carolina-Chapel Hill, began in the early 1990s to replace water with carbon dioxide in manufacturing paint, work funded by both the National Science Foundation and the EPA's Design for the Environment Program. DeSimone is now chairman of Micell, and the company is actively investigating ways to employ the same basic technology in a variety of other industrial uses. Micell's 20,000-pound, 9 x 9 x 9 ft. dry cleaning machine is twice as large as traditional dry cleaning equipment. At $150,000, its cost is "triple to quadruple" mat of a state-of-the-art perchloroethylene machine, said William Fisher, executive director of the International Fabricare Institute. And that's not including the $25,000 franchise fee Micell is charging. The MIC02 machine's price and size would deter the average "Mom and Pop" dry cleaner from purchasing it, said Bill Seitz, executive director of National Dry Cleaners Association International, noting that a C02-based dry cleaning machine being developed by Global Technologies, of El Segundo, Calif., is much smaller and less expensive. The cost of investing in either technology could be offset by legislation currently being considered by Congress that would offer tax credits for environmentally preferable investments, said Mary Ellen Weber, director of EPA's Economics, Exposure, and Technology division. Micell is betting that its machinery's lower operating costs will counterbalance its up-front expenses, especially because using C0 2 frees small businesses from hassling with
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regulations governing the use of traditional dry cleaning solvents. Ted Williams, owner of the first dry cleaners to adopt the process, Hangers of Wilmington, N.C., said that he previously paid $10 for each pound of "perc" his company used—North Carolina is one of 11 states to levy a perchloroethylene surcharge—as well as $1800 in extra insurance. Many in die industry expect this regulatory burden to grow. The Halogenated Solvents Industry Alliance's records show that 83 million pounds of perchloroethylene were used in 1997, and perc is one of the most common contaminants in urban air, according to David DeRosa, a toxics campaigner for Greenpeace. The Centers for Disease Control estimate mat 74% of Americans have measurable amounts of the contaminant in their blood. EPA classifies perc as a probable human carcinogen and regulates it as a hazardous air pollutant. Perchloroetirylene is a "serious liability" for dry cleaners, for the industry faces the threat of million-dollar lawsuits, Fisher said. "If you have a perc plant, the chances are 90% that you probably have contamination if your equipment is more than five-toseven years old," he said. Micell is hoping that consumers will be attracted to the environmental benefits of C02, and the company is already advertising the new technology's "greenness." Besides being gentler on clothing, the company says that there is no need to "air out" clothes drycleaned with liquid C0 2 because, unlike perchloroethylene, it does not linger inside plastic bags. Micell's goal is to be as environmentally friendly as possible, DeYoung stressed. To the best of his knowledge, none of the compounds used in the process are regulated. Over 98% of the C0 2 is recycled through a vapor recovery system. Even the detergent residue resulting from the dry cleaning process can be burned as fuel, Harbinson said. —KELLYN S. BETTS
