Articles | Volume 21, issue 3
https://doi.org/10.5194/acp-21-2053-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-21-2053-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
11 Feb 2021
Research article |
| 11 Feb 2021
| 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
Earth System Science Programme, Faculty of Science, The Chinese
University of Hong Kong, Hong Kong, China
Rongshuang Xu
Earth System Science Programme, Faculty of Science, The Chinese
University of Hong Kong, Hong Kong, China
Jack Choczynski
Department of Chemistry, University of California Riverside,
Riverside, CA, USA
James F. Davies
Department of Chemistry, University of California Riverside,
Riverside, CA, USA
Dongwan Ham
Department of Earth and Environmental Sciences, Jeonbuk National
University, Jeollabuk-do, Republic of Korea
Mijung Song
Department of Earth and Environmental Sciences, Jeonbuk National
University, Jeollabuk-do, Republic of Korea
Andreas Zuend
Department of Atmospheric and Oceanic Sciences, McGill University,
Montréal, Quebec, Canada
Wentao Li
Department of Chemistry, The Chinese University of Hong Kong, Hong
Kong, China
Ying-Lung Steve Tse
Department of Chemistry, The Chinese University of Hong Kong, Hong
Kong, China
Man Nin Chan
CORRESPONDING AUTHOR
Earth System Science Programme, Faculty of Science, The Chinese
University of Hong Kong, Hong Kong, China
The Institute of Environment, Energy and Sustainability, The Chinese
University of Hong Kong, Hong Kong, China
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Aqueous-phase •OH oxidation can potentially act as an important atmospheric sink for α-pinene-derived organosulfates (OSs). Such oxidation can also generate a variety of new OS products, and can be as a potential source for some atmospheric OSs with previously unknown origins.
Camilo Serrano Damha, Kyle Gorkowski, and Andreas Zuend
Atmos. Chem. Phys., 25, 5773–5792, https://doi.org/10.5194/acp-25-5773-2025, https://doi.org/10.5194/acp-25-5773-2025, 2025
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We implemented the BAT-VBS (Binary Activity Thermodynamics volatility basis set) aerosol thermodynamics model in the GEOS-Chem chemical transport model to efficiently account for organic aerosol water uptake, nonideal mixing, and impacts on the gas–particle partitioning of semi-volatile organics. Compared to GEOS-Chem's complex (dry) scheme, we show that the BAT-VBS model can predict substantial enhancements in organic aerosol mass concentration at moderate-to-high relative humidity.
Vahid Shahabadi, Cassandra Lefort, Hoi Tang Law, Man Nin Chan, and Thomas C. Preston
EGUsphere, https://doi.org/10.5194/egusphere-2025-2170, https://doi.org/10.5194/egusphere-2025-2170, 2025
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This research explores how organosulfate surfactants affect aerosol particles and their response to changes in relative humidity in the atmosphere. Using optical trapping and strong electric fields to investigate single particles, it is found that these surfactants can significantly lower surface tension, even in very small amounts. These findings are important for understanding how such particles influence cloud formation and properties like brightness.
Ryan Schmedding and Andreas Zuend
Atmos. Chem. Phys., 25, 327–346, https://doi.org/10.5194/acp-25-327-2025, https://doi.org/10.5194/acp-25-327-2025, 2025
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Four different approaches for computing the interfacial tension between liquid phases in aerosol particles were tested for particles with diameters from 10 nm to more than 5 μm. Antonov's rule led to the strongest reductions in the onset relative humidity of liquid–liquid phase separation and reproduced measured interfacial tensions for highly immiscible systems. A modified form of the Butler equation was able to best reproduce measured interfacial tensions in more miscible systems.
Liviana K. Klein, Allan K. Bertram, Andreas Zuend, Florence Gregson, and Ulrich K. Krieger
Atmos. Chem. Phys., 24, 13341–13359, https://doi.org/10.5194/acp-24-13341-2024, https://doi.org/10.5194/acp-24-13341-2024, 2024
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The viscosity of ammonium nitrate–sucrose–H2O was quantified with three methods ranging from liquid to solid state depending on the relative humidity. Moreover, the corresponding estimated internal aerosol mixing times remained below 1 h for most tropospheric conditions, making equilibrium partitioning a reasonable assumption.
Xiangxinyue Meng, Zhijun Wu, Jingchuan Chen, Yanting Qiu, Taomou Zong, Mijung Song, Jiyi Lee, and Min Hu
Atmos. Chem. Phys., 24, 2399–2414, https://doi.org/10.5194/acp-24-2399-2024, https://doi.org/10.5194/acp-24-2399-2024, 2024
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Our study revealed that particles predominantly exist in a semi-solid or solid state during clean winter days with RH below 30 %. However, a non-liquid to a liquid phase transition occurred when the aerosol liquid water (ALW) mass fraction surpassed 15 % (dry mass) at transition RH thresholds ranging from 40 % to 60 %. We also provide insights into the increasingly important roles of particle phase state variation and ALW in secondary particulate growth during haze formation in Beijing, China.
Ryan Schmedding and Andreas Zuend
Atmos. Chem. Phys., 23, 7741–7765, https://doi.org/10.5194/acp-23-7741-2023, https://doi.org/10.5194/acp-23-7741-2023, 2023
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Aerosol particles below 100 nm in diameter have high surface-area-to-volume ratios. The enrichment of compounds in the surface of an aerosol particle may lead to depletion of that species in the interior bulk of the particle. We present a framework for modeling the equilibrium bulk–surface partitioning of mixed organic–inorganic particles, including cases of co-condensation of semivolatile organic compounds and species with extremely limited solubility in the bulk or surface of a particle.
Rani Jeong, Joseph Lilek, Andreas Zuend, Rongshuang Xu, Man Nin Chan, Dohyun Kim, Hi Gyu Moon, and Mijung Song
Atmos. Chem. Phys., 22, 8805–8817, https://doi.org/10.5194/acp-22-8805-2022, https://doi.org/10.5194/acp-22-8805-2022, 2022
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In this study, the viscosities of particles of sucrose–H2O, AS–H2O, and sucrose–AS–H2O for OIRs of 4:1, 1:1, and 1:4 for decreasing RH, were quantified by poke-and-flow and bead-mobility techniques at 293 ± 1 K. Based on the viscosity results, the particles of binary and ternary systems ranged from liquid to semisolid, and even the solid state depending on the RH. Moreover, we compared the measured viscosities of ternary systems to the predicted viscosities with excellent agreement.
Rongshuang Xu, Sze In Madeleine Ng, Wing Sze Chow, Yee Ka Wong, Yuchen Wang, Donger Lai, Zhongping Yao, Pui-Kin So, Jian Zhen Yu, and Man Nin Chan
Atmos. Chem. Phys., 22, 5685–5700, https://doi.org/10.5194/acp-22-5685-2022, https://doi.org/10.5194/acp-22-5685-2022, 2022
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To date, while over a hundred organosulfates (OSs) have been detected in atmospheric aerosols, many of them are still unidentified, with unknown precursors and formation processes. We found the heterogeneous OH oxidation of an α-pinene-derived organosulfate (C10H17O5SNa, αpOS-249, αpOS-249) can proceed at an efficient rate and transform into more oxygenated OSs, which have been commonly detected in atmospheric aerosols and α-pinene-derived SOA in chamber studies.
Joseph Lilek and Andreas Zuend
Atmos. Chem. Phys., 22, 3203–3233, https://doi.org/10.5194/acp-22-3203-2022, https://doi.org/10.5194/acp-22-3203-2022, 2022
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Depending on temperature and chemical makeup, certain aerosols can be highly viscous or glassy, with atmospheric implications. We have therefore implemented two major upgrades to the predictive viscosity model AIOMFAC-VISC. First, we created a new viscosity model for aqueous electrolyte solutions containing an arbitrary number of ion species. Second, we integrated the electrolyte model within the existing AIOMFAC-VISC framework to enable viscosity predictions for organic–inorganic mixtures.
Hang Yin, Jing Dou, Liviana Klein, Ulrich K. Krieger, Alison Bain, Brandon J. Wallace, Thomas C. Preston, and Andreas Zuend
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Iodine and carbonate species are important components in marine and dust aerosols, respectively. We introduce an extended version of the AIOMFAC thermodynamic mixing model, which includes the ions I−, IO3−, HCO3−, CO32−, OH−, and CO2(aq) as new species, and we discuss two methods for solving the carbonate dissociation equilibria numerically. We also present new experimental water activity data for aqueous iodide and iodate systems.
Dalrin Ampritta Amaladhasan, Claudia Heyn, Christopher R. Hoyle, Imad El Haddad, Miriam Elser, Simone M. Pieber, Jay G. Slowik, Antonio Amorim, Jonathan Duplissy, Sebastian Ehrhart, Vladimir Makhmutov, Ugo Molteni, Matti Rissanen, Yuri Stozhkov, Robert Wagner, Armin Hansel, Jasper Kirkby, Neil M. Donahue, Rainer Volkamer, Urs Baltensperger, Martin Gysel-Beer, and Andreas Zuend
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Jack M. Choczynski, Ravleen Kaur Kohli, Craig S. Sheldon, Chelsea L. Price, and James F. Davies
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Relative humidity (RH) and hygroscopicity play an important role in regulating the physical, chemical, and optical properties of aerosol. In this work, we develop a new method to characterize hygroscopicity using particle levitation. We levitate two droplets with an electrodynamic balance and measure their size with light-scattering methods using one droplet as a probe of the RH. We demonstrate highly accurate and precise measurements of the RH and hygroscopic growth of a range of samples.
Young-Chul Song, Joseph Lilek, Jae Bong Lee, Man Nin Chan, Zhijun Wu, Andreas Zuend, and Mijung Song
Atmos. Chem. Phys., 21, 10215–10228, https://doi.org/10.5194/acp-21-10215-2021, https://doi.org/10.5194/acp-21-10215-2021, 2021
Short summary
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We report viscosity of binary mixtures of organic material / H2O and inorganic salts / H2O, as well as ternary mixtures of organic material / inorganic salts/ H2O, over the atmospheric relative humidity (RH) range. The viscosity measurements indicate that the studied mixed organic–inorganic particles range in phase state from liquid to semi-solid or even solid across the atmospheric RH range at a temperature of 293 K.
Weigang Wang, Ting Lei, Andreas Zuend, Hang Su, Yafang Cheng, Yajun Shi, Maofa Ge, and Mingyuan Liu
Atmos. Chem. Phys., 21, 2179–2190, https://doi.org/10.5194/acp-21-2179-2021, https://doi.org/10.5194/acp-21-2179-2021, 2021
Short summary
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Aerosol mixing state regulates the interactions between water molecules and particles and thus controls aerosol activation and hygroscopic growth, which thereby influences visibility degradation, cloud formation, and its radiative forcing. However, there are few studies attempting to investigate their interactions with water molecules. Here, we investigated the effect of organic coatings on the hygroscopic behavior of the inorganic core.
Young-Chul Song, Ariana G. Bé, Scot T. Martin, Franz M. Geiger, Allan K. Bertram, Regan J. Thomson, and Mijung Song
Atmos. Chem. Phys., 20, 11263–11273, https://doi.org/10.5194/acp-20-11263-2020, https://doi.org/10.5194/acp-20-11263-2020, 2020
Short summary
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We report the liquid–liquid phase separation (LLPS) of organic aerosol consisting of α-pinene- and β-caryophyllene-derived ozonolysis products and commercial organic compounds. As compositional complexity increased from one to two organic species, LLPS occurred over a wider range of average O : C values (increasing from 0.44 to 0.67). These results provide further evidence that LLPS is likely frequent in organic aerosol particles in the troposphere, even in the absence of inorganic salt.
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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.
This work demonstrates that organic compounds present at or near the surface of aerosols can be...
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