Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon
Name
Kroll_Heterogeneous Oxidation.pdf
Size
5.36 MB
Format
Adobe PDF
Checksum (MD5)
9452266aa6c9aa292ef743c1895cbdf8
Author(s)
Wilson, Kevin R.
Kroll, Jesse
Lim, Christopher Yung-Ta
Kessler, Sean
Date Issued
September 2015
Journal
The Journal of Physical Chemistry A
Publisher
American Chemical Society (ACS)
Citation
Kroll, Jesse H., Christopher Y. Lim, Sean H. Kessler, and Kevin R. Wilson. “Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.” The Journal of Physical Chemistry A 119, no. 44 (November 5, 2015): 10767–10783. © 2015 American Chemical Society
Version
Final published version
Abstract
Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C–C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3–13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major role in the lifecycle of atmospheric OA.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1021/acs.jpca.5b06946
