Heterogeneous oxidation of squalene film by ozone under various indoor conditions

L. Petrick, Y. Dubowski

Research output: Contribution to journalArticlepeer-review

90 Scopus citations

Abstract

The effects of indoor conditions (ozone concentration, temperature, relative humidity (RH), and the presence of NOx) on heterogeneous squalene oxidation were studied with Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy. The heterogeneous kinetics of squalene-ozone reaction revealed a pseudo-first-order reaction rate constant of 1.22 × 10-5/s at [O3] = 40 ppb. Oxidation kinetics were insensitive to temperature over the range of 24-58 ± 2°C as well as to RH and presence of NOx. Products, however, were affected by the environmental parameters. As temperature was increased, fewer surface products and more low molecular weight gaseous products were observed. Lower air exchange rates also enhanced gas phase reactions, allowing for formation of secondary gas phase products. As RH increased, there was a shift in product distribution from ketones to aldehydes, and the presence of NOx during squalene ozonolysis resulted in the formation of nitrated oxidation products. Identified surface products included 6-methyl-5-hepten-2-one, geranyl acetone, and long chain ketones and aldehydes, while gas phase products included formaldehyde, acetone, 4-oxopentanal (4-OPA), glyoxal, and pyruvic acid.

Original languageEnglish
Pages (from-to)381-391
Number of pages11
JournalIndoor Air
Volume19
Issue number5
DOIs
StatePublished - Oct 2009
Externally publishedYes

Keywords

  • Heterogeneous
  • Indoor
  • Oxidation
  • Ozone
  • Squalene

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