Fast oxidation of sulfur dioxide by hydrogen peroxide in deliquesced aerosol particles

Tengyu Liu, Simon L Clegg, Jonathan P D Abbatt

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155 Citations (Scopus)
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Atmospheric sulfate aerosols have important impacts on air quality, climate, and human and ecosystem health. However, current air-quality models generally underestimate the rate of conversion of sulfur dioxide (SO2) to sulfate during severe haze pollution events, indicating that our understanding of sulfate formation chemistry is incomplete. This may arise because the air-quality models rely upon kinetics studies of SO2 oxidation conducted in dilute aqueous solutions, and not at the high solute strengths of atmospheric aerosol particles. Here, we utilize an aerosol flow reactor to perform direct investigation on the kinetics of aqueous oxidation of dissolved SO2 by hydrogen peroxide (H2O2) using pH-buffered, submicrometer, deliquesced aerosol particles at relative humidity of 73 to 90%. We find that the high solute strength of the aerosol particles significantly enhances the sulfate formation rate for the H2O2 oxidation pathway compared to the dilute solution. By taking these effects into account, our results indicate that the oxidation of SO2 by H2O2 in the liquid water present in atmospheric aerosol particles can contribute to the missing sulfate source during severe haze episodes.

Original languageEnglish
Pages (from-to)1354-1359
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number3
Early online date6 Jan 2020
Publication statusPublished - 21 Jan 2020


  • Aerosol kinetics
  • air pollution
  • Chinese haze
  • Multiphase chemistry
  • Sulfate aerosol

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