Published in

European Geosciences Union, Atmospheric Chemistry and Physics, 2(22), p. 917-928, 2022

DOI: 10.5194/acp-22-917-2022

Links

Tools

Export citation

Search in Google Scholar

Secondary organic aerosol formation from the oxidation of decamethylcyclopentasiloxane at atmospherically relevant OH concentrations

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Green circle
Postprint: archiving allowed
Green circle
Published version: archiving allowed
Data provided by SHERPA/RoMEO

Abstract

Decamethylcyclopentasiloxane (D5, C10H30O5Si5) is measured at parts per trillion (ppt) levels outdoors and parts per billion (ppb) levels indoors. Primarily used in personal care products, its outdoor concentration is correlated to population density. Since understanding the aerosol formation potential of volatile chemical products is critical to understanding particulate matter in urban areas, the secondary organic aerosol yield of D5 was studied under a wide range of OH concentrations and, correspondingly, OH exposures using both batch-mode chamber and continuously run flow tube experiments. These results were comprehensively analyzed and compared to two other secondary organic aerosol (SOA) yield datasets from literature. It was found that the SOA yield from the oxidation of D5 is extremely dependent on either the OH concentration or exposure. For OH concentrations of ≲ 107 molec.cm-3 or OH exposures of ≲ 2 × 1011 molec.scm-3, the SOA yield is largely < 5 % and usually ∼ 1 %. This is significantly lower than SOA yields previously reported. Using a two-product absorptive partitioning model for the upper bound SOA yields, the stoichiometric mass fraction and absorptive partitioning coefficients are, for the first product, α1 = 0.056 and KOM,1 = 0.022 m3 µg−1; for the second product, they are α2 = 7.7 and KOM,2 = 4.3 × 10−5 m3 µg−1. Generally, there are high SOA yields (> 90 %) at OH mixing ratios of 5 × 109 molec.cm-3 or OH exposures above 1012 molec.scm-3.