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Overall kinetics of heterogeneous elemental mercury reactions on TiO2 sorbent particles with UV radiation
Citation:
Lee, T. G., P. Biswas, AND E J. Hedrick. Overall kinetics of heterogeneous elemental mercury reactions on TiO2 sorbent particles with UV radiation. INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH. American Chemical Society, Washington, DC, 43(6):1411-1417, (2001).
Impact/Purpose:
The goals of this research are to develop a method for measuring Hg concurrently with multiple metals at concentration levels of interest in human and dietary exposure studies using DIN-ICP/MS, and to validate the method by determining the concentration of multiple-metals plus total Hg in (1) drinking water, (2) beverages and (3) archived NHEXAS composite diet samples. A sub-objective of this work is to write a report for research planners that compares the costs and relative merits of the currently available Hg methods. This report would contain single lab data for Hg in dietary samples using ICP/MS, cold vapor atomic absorption (CVAA), and cold vapor atomic fluorescence (CVAF).
Description:
A system consisting of a photochemical reaction was used to evaluate the kinetic parameters, such as reaction order and rate constant for the elemental mercury uptake by TiO2 in the presence of uv irradiation. TiO2 particles generated by an aerosol route were used in a fixed bed system along with commercial Degusa P25 TiO2 powders. In the presence of uv irradiation, the rate of Hg photooxidation was evaluated as a function of Hg concentration, uv intensity, and available surface area (actrivated sites). Reaction orders with respect to the gas phase mercury concentration and the uv intensity were found to be 1.40+/-0.1 and 0.35+/-0.05, respectively. For the case of in situ generated TiO2 particles, mercury concenration and uv intensity were found to be 1.1+/-0.1 and 0.390, respectively. From results of the experiments at various reaction temperatures, the apparent activation energy, and the experimentally observed rate constant were calculated.
