Phase Behavior of Internal Mixtures of Hydrocarbon-like Primary Organic Aerosol and Secondary Aerosol Based on Their Differences in Oxygen-to-Carbon Ratios

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

12 Scopus Citations
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Author(s)

  • Fabian Mahrt
  • Yuanzhou Huang
  • Julia Zaks
  • Annesha Devi
  • Long Peng
  • Paul E. Ohno
  • Scot T. Martin
  • Markus Ammann
  • Allan K. Bertram

Detail(s)

Original languageEnglish
Pages (from-to)3960-3973
Journal / PublicationEnvironmental Science and Technology
Volume56
Issue number7
Online published16 Mar 2022
Publication statusPublished - 5 Apr 2022
Externally publishedYes

Link(s)

Abstract

The phase behavior, the number and type of phases, in atmospheric particles containing mixtures of hydrocarbon-like organic aerosol (HOA) and secondary organic aerosol (SOA) is important for predicting their impacts on air pollution, human health, and climate. Using a solvatochromic dye and fluorescence microscopy, we determined the phase behavior of 11 HOA proxies (O/C = 0-0.29) each mixed with 7 different SOA materials generated in environmental chambers (O/C 0.4-1.08), where O/C represents the average oxygen-to-carbon atomic ratio. Out of the 77 different HOA + SOA mixtures studied, we observed two phases in 88% of the cases. The phase behavior was independent of relative humidity over the range between 90% and <5%. A clear trend was observed between the number of phases and the difference between the average O/C ratios of the HOA and SOA components (ΔO/C). Using a threshold ΔO/C of 0.265, we were able to predict the phase behavior of 92% of the HOA + SOA mixtures studied here, with one-phase particles predicted for ΔO/C < 0.265 and two-phase particles predicted for ΔO/C ≥ 0.265. The threshold ΔO/C value provides a relatively simple and computationally inexpensive framework for predicting the number of phases in internal SOA and HOA mixtures in atmospheric models. © 2022 The Authors. Published by American Chemical Society.

Research Area(s)

  • air pollution, human health, organic aerosol particles, oxygen-to-carbon ratio, phase separation, secondary organic aerosol

Citation Format(s)

Phase Behavior of Internal Mixtures of Hydrocarbon-like Primary Organic Aerosol and Secondary Aerosol Based on Their Differences in Oxygen-to-Carbon Ratios. / Mahrt, Fabian; Huang, Yuanzhou; Zaks, Julia et al.
In: Environmental Science and Technology, Vol. 56, No. 7, 05.04.2022, p. 3960-3973.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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