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Proceedings Paper

Atmospheric transformation of volatile organic compounds
Author(s): Michael V. Henley; William R. Bradley; Sheryl E. Wyatt; G. M. Graziano; J. R. Wells
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Paper Abstract

To be able to understand and predict the concentration of a target compound in the atmosphere one must understand the atmospheric chemistry involved. The transformation of volatile organic compounds in the troposphere is predominantly driven by the interaction with the hydroxyl and nitrate radicals. The hydroxyl radical exists in daylight conditions and its reaction rate constant with an organic compound is typically very fast. The nitrate radical drives the nighttime chemistry. These radicals can scavenge hydrogen from an organic molecule generating secondary products that are often overlooked in detection schemes. Secondary products can be more stable and serve as a better target compound in detection schemes. The gas phase reaction of the hydroxyl radical (OH) with cyclohexanol (COL) has been studied. The rate coefficient was determined to be (19.0 +/- 4.8) X 10-12 cm3 molecule-1 s-1 (at 297 +/- 3 K and 1 atmosphere total pressure) using the relative rate technique with pentanal, decane, and tridecane as the reference compounds. Assuming an average OH concentration of 1 X 106 molecules cm-3, an atmospheric lifetime of 15 h is calculated for cyclohexanol. Products of the OH + COL reaction were determined to more clearly define cyclohexanol's atmospheric degradation mechanism. The observed products were: cyclohexanone, hexanedial, 3- hydroxycyclohexanone, and 4-hydroxycyclohexanone. Consideration of the potential reaction pathways suggest that each of these products is formed via hydrogen abstraction at a different site on the cyclohexanol ring.

Paper Details

Date Published: 28 July 2000
PDF: 7 pages
Proc. SPIE 4036, Chemical and Biological Sensing, (28 July 2000); doi: 10.1117/12.394076
Show Author Affiliations
Michael V. Henley, Air Force Research Lab. (United States)
William R. Bradley, Applied Research Associates (United States)
Sheryl E. Wyatt, Applied Research Associates (United States)
G. M. Graziano, Air Force Research Lab. (United States)
J. R. Wells, National Institute of Occupational Safety and Health (United States)

Published in SPIE Proceedings Vol. 4036:
Chemical and Biological Sensing
Patrick J. Gardner, Editor(s)

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