February 28, 2007, 1:00 PM - 2:00 PM, EST (18:00-19:00 GMT)

The NIEHS Superfund Basic Research Program is sponsoring this one-hour seminar. Dr. Eduardo Sáez (University of Arizona) will describe recent laboratory and field studies of catalytic destruction of PCE and TCE in soil vapor. Often, soil vapor contaminants are not destroyed on-site. They are commonly absorbed from the gas phase onto granular activated carbon, which in turn must be transported and treated off- site as a hazardous waste. Clearly there is a need for a soil vapor treatment technology that destroys the contaminants on-site. Here we report our experience developing just such a system to treat PCE and TCE — an automobile catalytic converter operated under controlled redox conditions. Most catalytic systems used to treat chlorinated organic compounds are operated under oxidizing conditions, which results in catalyst poisoning and a limited lifetime. Catalysts operated under reducing conditions are subject to rapid poisoning. In the system described here we introduce a chemically reducing gas such as propane and operate under near-stoichiometric conditions. This not only protects the catalyst from poisoning but also increases catalyst activity for PCE and TCE destruction. The reaction products are carbon dioxide and hydrochloric acid. The results of laboratory studies and a pilot field study conducted at an old dry-cleaning facility in Tucson, AZ, will be discussed.

• Avelino Eduardo Sáez, Department of Chemical and Environmental Engineering, The University of Arizona (esaez@engr.arizona.edu)

• Mike Gill, EPA Region 9 Hazardous Substances Technical Liaison (gill.michael@epa.gov)

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