Writer: Aaron Hoover
GAINESVILLE, Fla. --- University of Florida researchers have found a possible solution to a problem that has plagued air pollution control efforts for years: how to control smog-causing emissions from small sources ranging from industrial boilers to lawn mowers.
UF environmental engineering doctoral student Max Lee's findings could lead to new technology for reducing pollution in smog-ridden U.S. cities as well as in developing countries, where cheap, effective pollution controls are desperately needed.
"Everything for small sources currently is very, very expensive," said Eric Allen, professor emeritus of environmental engineering sciences and the chair of Lee's dissertation committee. "The importance of this technique is that it is oriented to the control of small sources and it is economical."
Lee, whose research was sponsored by the U.S. Air Force, said conventional pollution control techniques involve injecting a "reducing" gas into exhaust gas to convert nitrogen oxides, pollutants that are the primary ingredient in smog, to inert gasses.
Because the reducing and exhaust gases must be mixed in precise proportions at specific temperatures, the success of the technique requires emissions to be relatively constant. While this occurs with large emission sources such as coal- or natural gas-burning power plants, smaller sources such as boilers and small engines are operated intermittently and at varying capacity, meaning their emissions vary greatly. Additionally, the design and equipment costs for the reducing gas technology are extremely high.
Seeking a better method, Lee released known concentrations of nitrogen oxides through pellets of alumina, a common material found in many everyday items, coated with a special absorbent material. By measuring resulting emissions, he determined that the coated alumina removed 95 percent of the nitrogen oxides under conditions similar to combustion exhaust.
"Alumina is a readily available thing, and the nice thing is it's available in various forms such as highly durable pellets," Allen said.
Lee also found the pellets could be cleaned and then used again, he said.
"The main advantage of this technique is that the amount of material can be scaled to the size of the source, and initial costs are minimal," Lee said. "Also, the technique works over a wide temperature range representative of small-source exhaust temperatures."
Allen said the Air Force sponsored the UF research because it is seeking ways to control pollution from jet engine tests. But the use of coated alumina to control nitrogen oxides emissions could have far wider applications, he said. For example, Los Angeles has such a smog problem that officials have discussed restricting activities such as using a gasoline-powered lawn mower and barbecuing outdoors. Coated alumina could hold the key to new technologies that will reduce emissions from these and other small sources, he said.
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The above story is based on materials provided by University Of Florida. Note: Materials may be edited for content and length.
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