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Dechlorination Kinetics Of Monochlorobiphenyls By Fe/Pd: Effects Of Solvent, Temperature, And PCB Concentration
Citation:
FANG, Yuanxiang AND S. R. AL-ABED. Dechlorination Kinetics Of Monochlorobiphenyls By Fe/Pd: Effects Of Solvent, Temperature, And PCB Concentration. Flytzani-Stephanopoulos, Nam, Verykios (ed.), APPLIED CATALYSIS B: ENVIRONMENTAL. Elsevier Science Ltd, New York, NY, 78(3-4):371-280, (2008).
Impact/Purpose:
Journal Article
Description:
Well-known, yet undefined, changes in the conditions and activity of palladized zerovalent iron (Fe/Pd) over an extended period of time hindered a careful study of dechlorination kinetics in long-term experiments. A short-term experimental method was, therefore, developed to study the effects of temperature and solvent on the dechlorination of monochlorobiphenyls (MCBs), 2-chlorobiphenyl (2-ClBP), in particular by Fe/Pd. The experiments started with specifiied initial conditions and lasted only for 10 minutes. The average value (k) of the first-order rate constant for the dechlorination of 2-CIBP was 0.13 ± 0.03 (L m-2 h-1), not significantly different from the average values for 3-chlorobiphenyl and 4-chlorobiphenyl. The apparent activation energy was 20 ± 4 kJ mol-1) and 17 ± 7 kJ mol-1), in a temperature range between 4oC and 60oC, for the dechlorination of 2-CIBP using two batches of Fe/Pd catalyst. The k values decreased significantly in mixtures with a methanol concentration higher than 10%. The values of the rate constant were slightly influenced by the initial concentrations in the experiments at a low temperature and in a solution with a high methanol concentration. The concentration dependence was described with a Langmuir equation, based on the Langmuir-Hinshelwood mechanism that includes an adsorption step of a single species preceding a rate-determining catalytic reaction.
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Dechlorination Kinetics Of Monochlorobiphenyls By Fe/Pd: Effects Of Solvent, Temperature, And PCB Concentration