Articles | Volume 21, issue 3
Atmos. Chem. Phys., 21, 2053–2066, 2021
Atmos. Chem. Phys., 21, 2053–2066, 2021
Research article
11 Feb 2021
Research article | 11 Feb 2021

Effects of liquid–liquid phase separation and relative humidity on the heterogeneous OH oxidation of inorganic–organic aerosols: insights from methylglutaric acid and ammonium sulfate particles

Hoi Ki Lam et al.

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Subject: Aerosols | Research Activity: Laboratory Studies | Altitude Range: Troposphere | Science Focus: Chemistry (chemical composition and reactions)
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Cited articles

Altaf, M. B. and Freedman, M. A.: Effect of drying rate on aerosol particle morphology, J. Phys. Chem. Lett., 8, 3613–3618, 2017. 
Altaf, M. B., Zuend, A., and Freedman, M. A.: Role of nucleation mechanism on the size dependent morphology of organic aerosol, Chem. Commun., 52, 9220–9223, 2016. 
Arangio, A. M., Slade, J. H., Berkemeier, T., Pöschl, U., Knopf, D. A., and Shiraiwa, M.: Multiphase chemical kinetics of OH radical uptake by molecular organic markers of biomass burning aerosols: Humidity and temperature dependence, surface reaction, and bulk diffusion, J. Phys. Chem. A, 119, 4533–4544, 2015. 
Bertram, A. K., Martin, S. T., Hanna, S. J., Smith, M. L., Bodsworth, A., Chen, Q., Kuwata, M., Liu, A., You, Y., and Zorn, S. R.: Predicting the relative humidities of liquid-liquid phase separation, efflorescence, and deliquescence of mixed particles of ammonium sulfate, organic material, and water using the organic-to-sulfate mass ratio of the particle and the oxygen-to-carbon elemental ratio of the organic component, Atmos. Chem. Phys., 11, 10995–11006,, 2011. 
Brunamonti, S., Krieger, U. K., Marcolli, C., and Peter, T.: Redistribution of black carbon in aerosol particles undergoing liquid–liquid phase separation, Geophys. Res. Lett., 42, 2532–2539, 2015. 
Short summary
This work demonstrates that organic compounds present at or near the surface of aerosols can be subjected to oxidation initiated by gas-phase oxidants, such as hydroxyl radicals (OH). The heterogeneous reactivity is sensitive to their surface concentrations, which are determined by the phase separation behavior. This results of this work emphasize the effects of phase separation and potentially distinct aerosol morphologies on the chemical transformation of atmospheric aerosols.
Final-revised paper