Hydroxyl radical reactions with volatile organic compounds under simulated tropospheric conditions

Content Provider	Semantic Scholar
Author	Semadeni, Marco
Copyright Year	1994
Abstract	Kinetic investigations of the hydroxyl radical reaction with volatile organic compounds (VOC) are important to estimate the potential of VOCs in air pollution. The temperature dependence of the rate coefficients of the hydroxyl radical reaction with members of two classes of organic compounds have been measured under simulated tropospheric conditions using a competitive technique rebuilt in this laboratory. The hydroxyl radical reactions of the organic test compounds have been measured in the presence of given reference compounds over the temperature range (247–373) K. The rate coefficients obtained in the present study range from (11–42) ∞ 10-12 cm3 molecule-1 s-1 and from (1–52) ∞ 10-12 cm3 molecule-1 s-1 for the following ethers and aromatic compounds respectively: diethyl ether, methyl n-butyl ether, ethyl n-butyl ether, di-n-butyl ether, di-n-pentyl ether and benzene, toluene, benzaldehyde, phenol, o-cresol, m-cresol, p-cresol, arranged according to their increasing reactivity within their class. The temperature dependence of the hydroxyl radical reaction with methyl n-butyl ether, di-n-butyl ether, di-n-pentyl ether, m-cresol, p-cresol and benzaldehyde have been determined for the first time in this study. The Arrhenius parameters obtained confirm the negative temperature dependence often observed in this type of reaction. The results of the present study show, that the experimental system employed can provide accurate kinetic data and discrepancies occurred in previous studies have been resolved. Based on structure-activity relationships, the temperature dependent rate coefficients obtained have been used together with available literature data to determine the influence of an ether group on the reactivity of organic compounds, which resulted in a temperature dependent activating factor. The kinetic parameters evaluated in the present study have been used to estimate the tropospheric lifetimes of the organic compounds investigated. It has been shown, that the lifetimes of these relatively reactive compounds vary strongly, depending on the place and time of emission, i.e. latitude and season of the year. For the ethers, the tropospheric lifetimes vary within the range of 4 hours to 10 days and in the case of the aromatic compounds from 2 hours to 111 days.
File Format	PDF HTM / HTML
DOI	10.3929/ethz-a-001368078
Alternate Webpage(s)	https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/141777/eth-22386-02.pdf?isAllowed=y&sequence=2
Alternate Webpage(s)	https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/141777/eth-22386-01.pdf?isAllowed=y&sequence=1
Alternate Webpage(s)	https://doi.org/10.3929/ethz-a-001368078
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article