Connecting the Elementary Reaction Pathways of Criegee Intermediates to the Chemical Erosion of Squalene Interfaces during Ozonolysis
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division
Criegee intermediates (CI), formed in alkene ozonolysis, are central for controlling the multiphase chemistry of organic molecules in both indoor and outdoor environments. Here in this study, we examine the heterogeneous ozonolysis of squalene, a key species in indoor air chemistry. Aerosol mass spectrometry is used to investigate how the ozone (O3) concentration, relative humidity (RH), and particle size control reaction rates and mechanisms. Although the reaction rate is found to be independent of RH, the reaction products and particle size depend upon H2O. Under dry conditions (RH = 3%) the reaction produces high-molecular-weight secondary ozonides (SOZ), which are known skin irritants, and a modest change in particle size. Increasing the RH reduces the aerosol size by 30%, while producing mainly volatile aldehyde products, increases potential respiratory exposure. Chemical kinetics simulations link the elementary reactions steps of CI to the observed kinetics, product distributions, and changes in particle size. The simulations reveal that ozonolysis occurs near the surface and is O3-transport limited. Finally, the observed secondary ozonides are consistent with the formation of mainly secondary CI, in contrast to gas-phase ozonolysis mechanisms.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1456986
- Journal Information:
- Environmental Science and Technology, Vol. 51, Issue 23; Related Information: © 2017 American Chemical Society.; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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