Fundamental Time Scales Governing Organic Aerosol Multiphase Partitioning and Oxidative Aging

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

18 Scopus Citations
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Author(s)

  • Haofei Zhang
  • David R. Worton
  • Steve Shen
  • Gabriel Isaacman-Vanwertz
  • Kevin R. Wilson
  • Allen H. Goldstein

Detail(s)

Original languageEnglish
Pages (from-to)9768-9777
Journal / PublicationEnvironmental Science and Technology
Volume49
Issue number16
Online published22 Jul 2015
Publication statusPublished - 18 Aug 2015
Externally publishedYes

Abstract

Traditional descriptions of gas-particle partitioning of organic aerosols (OA) rely solely on thermodynamic properties (e.g., volatility). Under realistic conditions where phase partitioning is dynamic rather than static, the transformation of OA involves the interplay of multiphase partitioning with oxidative aging. A key challenge remains in quantifying the fundamental time scales for evaporation and oxidation of semivolatile OA. In this paper, we use isomer-resolved product measurements of a series of normal-alkanes (C18, C20, C22, and C24) to distinguish between gas-phase and heterogeneous oxidation products formed by reaction with hydroxyl radicals (OH). The product isomer distributions when combined with kinetics measurements of evaporation and oxidation enable a quantitative description of the multiphase time scales to be simulated using a single-particle kinetic model. Multiphase partitioning and oxidative transformation of semivolatile normal-alkanes under laboratory conditions is largely controlled by the particle phase state, since the time scales of heterogeneous oxidation and evaporation are found to occur on competing time scales (on the order of 10-1 h). This is in contrast to atmospheric conditions where heterogeneous oxidation time scales are expected to be much longer (on the order of 102 h), with gas-phase oxidation being the dominant process regardless of the evaporation kinetics. Our results demonstrate the dynamic nature of OA multiphase partitioning and oxidative aging and reveal that the fundamental time scales of these processes are crucial for reliably extending laboratory measurements of OA phase partitioning and aging to the atmosphere.

Citation Format(s)

Fundamental Time Scales Governing Organic Aerosol Multiphase Partitioning and Oxidative Aging. / Zhang, Haofei; Worton, David R.; Shen, Steve; Nah, Theodora; Isaacman-Vanwertz, Gabriel; Wilson, Kevin R.; Goldstein, Allen H.

In: Environmental Science and Technology, Vol. 49, No. 16, 18.08.2015, p. 9768-9777.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review