The persistence of a proxy for cooking emissions in megacities: A kinetic study of the ozonolysis of self-Assembled films by simultaneous small and wide angle X-ray scattering (SAXS/WAXS) and Raman microscopy

Adam Milsom, Adam M. Squires, Ben Woden, Nicholas J. Terrill, Andrew D. Ward, Christian Pfrang

Research output: Contribution to journalArticlepeer-review

17 Citations (SciVal)

Abstract

Cooking emissions account for a significant proportion of the organic aerosols emitted into the urban environment and high pollution events have been linked to an increased organic content on urban particulate matter surfaces. We present a kinetic study on surface coatings of self-Assembled (semi-solid) oleic acid-sodium oleate cooking aerosol proxies undergoing ozonolysis. We found clear film thickness-dependent kinetic behaviour and measured the effect of the organic phase on the kinetics for this system. In addition to the thickness-dependent kinetics, we show that significant fractions of unreacted proxy remain after extensive ozone exposure and that this effect scales approximately linearly with film thickness, suggesting that a late-stage inert reaction product may form and inhibit reaction progress-effectively building up an inert crust. We determine this by using a range of simultaneous analytical techniques; most notably Small-Angle X-ray Scattering (SAXS) has been used for the first time to measure the reaction kinetics of films of a wide range of thicknesses from ca. 0.59 to 73 μm with films <10 μm thick being of potential atmospheric relevance. These observations have implications for the evolution of particulate matter in the urban environment, potentially extending the atmospheric lifetimes of harmful aerosol components and affecting the local urban air quality and climate. This journal is

Original languageEnglish
Pages (from-to)364-381
Number of pages18
JournalFaraday Discussions
Volume226
Early online date7 Sept 2020
DOIs
Publication statusPublished - 1 Mar 2021

Bibliographical note

Funding Information:
This work was carried out with the support of the Diamond Light Source (DLS), instrument I22 (proposals SM21663 and NT23096). AM wishes to acknowledge funding from NERC SCENARIO DTP award number NE/L002566/1 and CENTA DTP; Eleonore Mason (University of Bath) is thanked for inviting AM/CP to her GI-SAXS beamtime. The authors would like to thank Andy Smith (DLS), Tim Snow (DLS) and Lee Davidson (DLS) for technical support during beamtime experiments; Jacob Boswell is acknowledged for help during beamtimes. The authors are grateful to the Central Laser Facility for access to key equipment for the Raman work carried out simultaneously with the DLS beamtime experiments.

Publisher Copyright:
© The Royal Society of Chemistry.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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