Grantee Research Project Results
Final Report: Kinetic and Mechanistic Studies of the Reactions of Hydroxyl Radical with the Chloroethenes over an Extended Temperature Range
EPA Grant Number: R826169Title: Kinetic and Mechanistic Studies of the Reactions of Hydroxyl Radical with the Chloroethenes over an Extended Temperature Range
Investigators: Taylor, Philip H.
Institution: University of Dayton
EPA Project Officer: Hahn, Intaek
Project Period: November 24, 1997 through November 23, 2000
Project Amount: $356,702
RFA: Exploratory Research - Environmental Engineering (1997) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Land and Waste Management
Objective:
The overall goal of this research is to determine the rates and mechanisms of OH reactions with the chloroethenes over an extended temperature range. The specific rate coefficients can be used to improve the design of hazardous waste incinerators with respect to these thermally stable products of incomplete combustion. Thermochemical data will also be determined under conditions when the rate of reverse dissociation is comparable with that of direct addition process and the chemically activated Cl elimination channel is negligibly slow. Specific goals of this research include: (1) The first absolute rate measurements of the reaction of OH with CH2=CCl2, cis-CHCl=CHCl, trans-CHCl=CHCl, CHCl=CCl2, and CCl2=CCl2 over an extended temperature range with determination of accurate Arrhenius or modified Arrhenius parameters; (2) determination of the relative importance of Cl elimination versus H atom abstraction at elevated temperatures; and (3) determination of the relative importance of Cl elimination versus adduct stabilization at lower temperatures.Summary/Accomplishments (Outputs/Outcomes):
Absolute rate coefficients for the reaction of hydroxyl radicals with chloroethylene, 1,1- and trans-1,2-dichloroethylene, trichloroethylene and tetrachloroethylene have been completed. Rate measurements were obtained using a laser photolysis/laser-induced fluorescence (LP/LIF) technique under slow flow conditions. Temperature ranges typically varied from 291 to 750 K. All measurements were recorded at atmospheric pressure. Ambient rate coefficients were generally in accord with prior measurements. The temperature dependence of the rate coefficients varied with chlorine substitution. The results were interpreted in terms of the relative importance of OH addition versus H atom abstraction pathways. For chloroethylene and 1,1-dichloroethylene, OH addition (with adduct stabilization) dominates at low temperatures and H-atom abstraction dominates above 700 K. For trans-1,2-dichloroethylene, trichloroethylene and tetrachloroethylene, chemically activated OH addition followed by Cl atom elimination is the dominant pathway at all but the lowest of temperatures. Kinetic isotope effect measurements support the absence of H-atom abstraction at elevated temperatures for trichloroethylene. The kinetic data were modeled with variational transition state theory using ab initio theory and Quantum RRK analysis. Arrhenius parameters for the individual compounds and the major reaction pathways based on QRRK modeling were calculated and assessed as a function of temperature and pressure. The relevance of these new measurements to atmospheric and incineration chemistry was evaluated.Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 6 publications | 2 publications in selected types | All 2 journal articles |
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Tichenor LB, Graham JL, Yamada T, Taylor PH. Kinetic and modeling studies of the reaction of hydroxyl radicals with tetrachloroethylene. Journal of Physical Chemistry A 2000;104(8):1700-1707. |
R826169 (1999) R826169 (Final) |
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Tichenor LB, El-Sinawi A, Yamada T, Taylor PH, Peng J, Hu X, Marshall P. Kinetic studies of the reaction of hydroxyl radicals with trichloroethylene and tetrachloroethylene. Chemosphere 2001;42(5-7):571-577 |
R826169 (1999) R826169 (Final) |
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Supplemental Keywords:
atmospheric chemistry, combustion chemistry, environmental engineering, exposure, air pollution., RFA, Scientific Discipline, Waste, Environmental Chemistry, Incineration/Combustion, Environmental Engineering, combustion contaminants, detailed chemical kinetics, toxic organic chemicals, high temperature reaction kinetics, hazardous waste incinerators, mechanistic study, hydroxyl radicals, laser induced flourescenceRelevant Websites:
http://www.udri.udayton.edu/enviroscienceProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.