Journal article
Decamethylcyclopentasiloxane (D5) Oxidation: Product Chemistry, Influence of RO 2 Fate, and Secondary Aerosol Production
ACS ES&T air
07/10/2026
DOI: 10.1021/acsestair.6c00037
Appears in UI Libraries Support Open Access
Abstract
Volatile methylsiloxanes (VMS), particularly decamethylcyclopentasiloxane (D5), are recognized anthropogenic precursors of secondary organic aerosol (SOA), yet their formation pathways, product distributions, and yields under atmospherically relevant conditions remain poorly constrained. This study examines D5-derived SOA across a wide range of OH exposures (OHexp) and peroxy radical (RO2) fates (RO2+HO2 and RO2+OH) in an oxidation flow reactor, with comparison to ambient and chamber samples. The siloxanol (1-hydroxynonamethylcyclopentasiloxane, D4TOH) is consistently observed. Under low OHexp and HO2-dominated regimes, samples contained multiple early generation siloxanols accompanied by dimers and high molecular weight products, contrary to expectations that such species require extensive oxidation. As OHexp and RO2 + OH reactivity increase, total SOA mass rises, and the fraction of unresolved material increases. The observations were compared to a volatility basis set (VBS) multigenerational oxidation kinetic box model with explicit siloxanols. The model’s strongly monotonic progression in volatility, aerosol yield, and degree of OH substitution in the polysiloxanol series diverged from experimental data, aside from the expected increase in yield with OHexp. At high OHexp, the product distribution and yield appear to be insensitive to RO2+HO2 vs RO2+OH fate.
Details
- Title: Subtitle
- Decamethylcyclopentasiloxane (D5) Oxidation: Product Chemistry, Influence of RO 2 Fate, and Secondary Aerosol Production
- Creators
- Saeideh Mohammadi - University of IowaJeewani N. Meepage - University of IowaChristopher E. Brunet - University of IowaRachel F. Marek - University of IowaKeri C. Hornbuckle - University of IowaEleanor C. Browne - University of Colorado SystemElizabeth A. Stone - University of IowaCharles O. Stanier - University of Iowa
- Resource Type
- Journal article
- Publication Details
- ACS ES&T air
- DOI
- 10.1021/acsestair.6c00037
- ISSN
- 2837-1402
- eISSN
- 2837-1402
- Publisher
- American Chemical Society
- Grant note
- National Institutes of Health (NIH): P42ES013661 National Science Foundation (NSF): AGS-2028764
The authors acknowledge Nathaniel Massa, Benjamin McMillan, Carlos Gutierrez, and Nora Gibson for their assistance with the OFR experiments and data analysis. Special thanks go to Josie K. Welker for sharing data, assisting with analytical methodology, and providing feedback during manuscript preparation and to Hanalei R. Lewine for sharing experimental data and chemical mechanisms, as well as contributing feedback during manuscript preparation. This research was funded by the National Science Foundation (NSF, Grant AGS-2028764 and AGS-2029017) and the National Institute of Environmental Health Sciences of the National Institutes of Health (NIEHS/NIH P42ES013661). We also thank Ricardo Toledo-Crow and Dr. Drew Gentner for organizing and coordinating AEROMMA-2022 at the Graduate Center Advanced Science Research Center NGENS Facility at the City University of New York (CUNY) for access to collect ambient PM2.5.
- Language
- English
- Electronic publication date
- 07/10/2026
- Academic Unit
- Civil and Environmental Engineering; Occupational and Environmental Health; IIHR--Hydroscience and Engineering; Interdisciplinary Graduate Program in Human Toxicology; Chemistry; Chemical and Biochemical Engineering
- Record Identifier
- 9985183418102771
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