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Environmentally Friendly Tires
If you stacked all the stockpiled and landfilled waste tires in the U.S. on top of each other, they would reach the moon. Lay them end to end and they would encircle the globe more than 140 times. An environmental nightmare. Researchers in Illinois see the huge tire supply as a resource to help clean the air of fossil fuel pollutants.
Writing in the November issue of the scientific journal Energy and Fuels, a joint research team from the University of Illinois and the Illinois State Geological Survey reports that activated carbon made from discarded tires can be used to remove fossil fuel pollutants from smokestack emissions. The peer-reviewed, bimonthly journal is published by the American Chemical Society, the world's largest scientific society.
The report is part of a special issue of the journal highlighting research on adsorbents and catalysts for clean energy and emissions control. Team members include Mark Rood, Ph.D., of the university's Urbana-Champaign campus, Massoud Rostam-Abadi, Ph.D., with the Geological Survey, and graduate student Christ Lehmann.
There are 2 to 3 billion waste tires in this country, either stockpiled or in landfills, and at least 240 million more are being added each year, according to a 1993 estimate by the U.S. Environmental Protection Agency. "Tire rubber could potentially be an ideal material to make activated carbon since it is inexpensive, it has a high carbon content, and it has low ash and sulfur contents," claims Rood. Most other research with waste tires involves finding ways of recovering oils and gases, he says, but "little work has been performed to tailor the properties of tire-derived activated carbons to solve air pollution problems." Activated carbon is typically made from wood, nut shells and coal.
Tests with simulated flue-gas streams (smokestack emissions) show that activated carbon made from waste tires generally has a larger adsorption capacity of mercury than coal-derived activated carbon.
In addition to cleaning smokestack emissions, another possible market for activated carbon adsorbents made from discarded tires is the automotive industry. Uses could include canisters that collect and prevent the release of gasoline vapors into the environment, and lighter-weight, lower-pressure storage systems for vehicles fueled by compressed natural gas.