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A Mechanistic Model for Mercury Capture With in-Situ Generated Titania Particles: Role of Water Vapor

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Abstract:A mechanistic model to predict the capture of gas phase mercury species using in-situ generated titania nanosize particles activated by UV irradiation is developed. The model is an extension of a recently reported model1 for photochemical reactions that accounts for the rates of electron-hole pair generation, adsorption of the compound to be oxidized and the adsorption of water vapor. The role of water vapor on the removal efficiency of Hg was investigated to evaluate the rates of mercury oxidation at different water vapor concentrations. As the water vapor concentration is increased, more OH-radical species are generated on the surface of the titania particle, increasing the number of active sites for the photo-oxidation and capture of mercury. At very high water vapor concentrations, competitive adsorption is expected to be important and reduce the number of sites available for photo-oxidation of mercury. The predictions of the developed phenomenological model agreed well with the measured mercury oxidation rates in this study, and with the data on oxidation of organic compounds reported in the literature.
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Citation:Rodriguez, S., C. B. Almquist, T. G. Lee, M. Furuuchi, E. J. Hedrick, and P. Biswas. A Mechanistic Model for Mercury Capture With in-Situ Generated Titania Particles: Role of Water Vapor. JOURNAL OF AIR AND WASTE MANAGEMENT ASSOCIATION 54(2):149-156, (2004).
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Contact: Mary P. O'Bryant - (919)-541-4871 or obriant.mary@epa.gov
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Division: Microbiological & Chemical Exposure Assessment Division
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Branch: Chemical Exposure Research Branch
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Product Type: Journal
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Published: 02/01/2004
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Downloads:
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Bullet Item A Mechanistic Model for Mercury Capture With in-Situ Generated Titania Particles: Role of Water Vapor
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