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EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON
Li*, Y H., S D. Serre**, C W. Lee*, AND B K. Gullett*. EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON. Presented at Conference on Air Quality II, McLean, VA, 9/19-21/00.
The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash content, were tested for Hgo adsorption capacity. From both fixed-bed and flow reactor experimental results, the moisture on activated-carbon surfaces has been found to have a significant effect on Hgo adsorption. A common effect of moisture on Hgo adsorption was observed for all three samples, despite extreme differences in their ash content, suggesting that this effect is not associated with ash content. Temperature-programmed desorption (TPD) experiments performed on the carbon samples after the Hgo adsorption experiments indicated that chemisorption of Hgo is a dominant process over physisorption for the moisture-containing carbon samples, and diminished for the heat-traeted moisture-free samples. X-ray absorption fine-structure (XAFS) spectroscopy results provide evidence that mercury bonding on the carbon surfaces was associated with oxygen through a mechanism likely involving elecron transfer processes. The aromatic resonance-stablized structures in equilibrium with the oxygen surfaec functional groups take up electrons from the mercury atoms.
Record Details:Record Type: DOCUMENT (PRESENTATION/PAPER)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
AIR POLLUTION PREVENTION AND CONTROL DIVISION
AIR POLLUTION TECHNOLOGY BRANCH