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Ye Q, Yao M, Wang W, Li Z, Li C, Wang S, Xiao H, Zhao Y. Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168736. [PMID: 37996034 DOI: 10.1016/j.scitotenv.2023.168736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 11/06/2023] [Accepted: 11/19/2023] [Indexed: 11/25/2023]
Abstract
There is growing evidence that the interactions between sulfur dioxide (SO2) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO2 remains unknown. In this study, we investigate the multiphase reactions of SO2 with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO2 on toluene SOA was determined to be on the order of 10-4, depending strikingly on aerosol water content. POs contribute significantly to the multiphase reactivity of toluene SOA, but they can only explain a portion of the measured SO2 uptake, suggesting the presence of other reactive species in SOA that also contribute to the particle reactivity toward SO2. The second-order reaction rate constant (kII) between S(IV) and toluene-derived POs was estimated to be in the range of the kII values previously reported for commercially available POs (e.g., 2-butanone peroxide and 2-tert-butyl hydroperoxide) and the smallest (C1-C2) and biogenic POs. In addition, unlike commercial POs that can efficiently convert S(IV) into both inorganic sulfate and organosulfates, toluene-derived POs appear to mainly oxidize S(IV) to inorganic sulfate. Our study reveals the multiphase reactivity of typical anthropogenic SOA and POs toward SO2 and will help to develop a better understanding of the formation and evolution of atmospheric secondary aerosol.
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Affiliation(s)
- Qing Ye
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Min Yao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Wei Wang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ziyue Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chenxi Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shunyao Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Huayun Xiao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yue Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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2
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Effects of viscoelasticity on moisture sorption of maltodextrins. Food Hydrocoll 2023. [DOI: 10.1016/j.foodhyd.2023.108481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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3
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Gao K, Koch HC, Zhou CW, Kanji ZA. The dependence of soot particle ice nucleation ability on its volatile content. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:2043-2069. [PMID: 36043854 DOI: 10.1039/d2em00158f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Aviation soot can affect contrail and cirrus cloud formation and impact climate. A product of incomplete combustion, soot particles, are fractal and hydrophobic aggregates comprising carbonaceous spheres with complex physicochemical properties. In the cirrus cloud regime, the surface wettability and pore abundance of soot particles are important determinants for their ice nucleation ability via pore condensation and freezing. In the atmosphere, soot particles can undergo various ageing processes which modify their surface chemistry and porosity, thus acting as ice nucleating particles with varying abilities as a function of ageing. In this study, size-selected soot particles were treated by thermal denuding at 573 K in a pure nitrogen (N2) or synthetic air (N2 + O2) flow and then exposed to varying relative humidity conditions at a fixed temperature in the range from 218 to 243 K, to investigate the role of volatile content in the ice nucleation ability. Both organic-lean and organic-rich propane (C3H8) flame soot particles, as well as two types of commercially available carbon black soot particles with high and low surface wettability, were tested. The size and mass distribution of soot aerosol were monitored during the ice nucleation experiments. Bulk soot samples also prepared in pure N2 or synthetic air environments at 573 K were characterised by thermogravimetric analysis, Fourier transform infrared spectroscopy and dynamic vapour sorption measurements, to reveal the relation between denuding volatile content, associated soot particle property modifications and the ice nucleation ability. Our study shows that thermal denuding induces a change in soot particle porosity playing a dominant role in regulating its ice nucleation via the pore condensation and freezing mechanism. The enrichment in mesopore (2-50 nm) availability may enhance soot ice nucleation. The presence of O2 in the thermal denuding process may introduce new active sites on soot particles for water interaction and increase soot surface wettability. However, these active sites only facilitate soot ice nucleation when mesopore structures are available. We conclude that a change in volatile content modifies both morphological properties and surface chemistry for soot particles, but porosity change plays the dominant role in regulating soot particle ice nucleation ability.
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Affiliation(s)
- Kunfeng Gao
- School of Energy and Power Engineering, Beihang University, Beijing, China.
- Shenyuan Honours College of Beihang University, Beihang University, Beijing, China
- Department of Environmental Systems Science, Institute for Atmospheric and Climate Science, ETH Zurich, Zurich 8092, Switzerland.
| | | | - Chong-Wen Zhou
- School of Energy and Power Engineering, Beihang University, Beijing, China.
| | - Zamin A Kanji
- Department of Environmental Systems Science, Institute for Atmospheric and Climate Science, ETH Zurich, Zurich 8092, Switzerland.
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4
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Li J, Knopf DA. Representation of Multiphase OH Oxidation of Amorphous Organic Aerosol for Tropospheric Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:7266-7275. [PMID: 33974411 DOI: 10.1021/acs.est.0c07668] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic aerosol (OA) is ubiquitous in the atmosphere and, during transport, can experience chemical transformation with consequences for air quality and climate. Prediction of the chemical evolution of OA depends on its reactivity with atmospheric oxidants such as the OH radical. OA particles undergo amorphous phase transitions from liquid to solid (glassy) states in response to temperature changes, which, in turn, will impact its reactivity toward OH oxidation. To improve the predictability of OA reactivity toward OH oxidation, the reactive uptake coefficients (γ) of OH radicals reacting with triacontane and squalane serving as amorphous OA surrogates were measured at temperatures from 213-293 K. γ increases strongest with temperature when the organic species is in the liquid phase, compared to when being in the semisolid or solid phase. The resistor model is applied, accounting for the amorphous phase state changes using the organic species' glass transition temperature and fragility, to evaluate the physicochemical parameters of the temperature dependent OH uptake process. This allows for the derivation of a semiempirical formula, applicable to models, to predict the degree of oxidation and chemical lifetime of the condensed-phase organic species for typical tropospheric temperature and humidity when OA particle viscosity is known.
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Affiliation(s)
- Jienan Li
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Daniel A Knopf
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794, United States
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5
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He Y, Akherati A, Nah T, Ng NL, Garofalo LA, Farmer DK, Shiraiwa M, Zaveri RA, Cappa CD, Pierce JR, Jathar SH. Particle Size Distribution Dynamics Can Help Constrain the Phase State of Secondary Organic Aerosol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:1466-1476. [PMID: 33417446 DOI: 10.1021/acs.est.0c05796] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Particle phase state is a property of atmospheric aerosols that has important implications for the formation, evolution, and gas/particle partitioning of secondary organic aerosol (SOA). In this work, we use a size-resolved chemistry and microphysics model (Statistical Oxidation Model coupled to the TwO Moment Aerosol Sectional (SOM-TOMAS)), updated to include an explicit treatment of particle phase state, to constrain the bulk diffusion coefficient (Db) of SOA produced from α-pinene ozonolysis. By leveraging data from laboratory experiments performed in the absence of a seed and under dry conditions, we find that the Db for SOA can be constrained ((1-7) × 10-15 cm2 s-1 in these experiments) by simultaneously reproducing the time-varying SOA mass concentrations and the evolution of the particle size distribution. Another version of our model that used the predicted SOA composition to calculate the glass-transition temperature, viscosity, and, ultimately, Db (∼10-15 cm2 s-1) of the SOA was able to reproduce the mass and size distribution measurements when we included oligomer formation (oligomers accounted for about a fifth of the SOA mass). Our work highlights the potential of a size-resolved SOA model to constrain the particle phase state of SOA using historical measurements of the evolution of the particle size distribution.
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Affiliation(s)
- Yicong He
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Ali Akherati
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Theodora Nah
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China
| | - Nga L Ng
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Lauren A Garofalo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Delphine K Farmer
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Manabu Shiraiwa
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Rahul A Zaveri
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Christopher D Cappa
- Department of Civil and Environmental Engineering, University of California Davis, Davis, California 95616, United States
| | - Jeffrey R Pierce
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Shantanu H Jathar
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
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6
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Wallace BJ, Price CL, Davies JF, Preston TC. Multicomponent diffusion in atmospheric aerosol particles. ACTA ACUST UNITED AC 2021. [DOI: 10.1039/d0ea00008f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Condensed phase mass transport in single aerosol particles is investigated using a linear quadrupole electrodynamic balance (LQ-EDB) and the Maxwell–Stefan (MS) framework.
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Affiliation(s)
- Brandon J. Wallace
- Department of Atmospheric and Oceanic Sciences
- Department of Chemistry
- McGill University
- Montreal
- Canada
| | - Chelsea L. Price
- Department of Chemistry
- University of California Riverside
- Riverside
- USA
| | - James F. Davies
- Department of Chemistry
- University of California Riverside
- Riverside
- USA
| | - Thomas C. Preston
- Department of Atmospheric and Oceanic Sciences
- Department of Chemistry
- McGill University
- Montreal
- Canada
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7
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Sullivan RC, Boyer-Chelmo H, Gorkowski K, Beydoun H. Aerosol Optical Tweezers Elucidate the Chemistry, Acidity, Phase Separations, and Morphology of Atmospheric Microdroplets. Acc Chem Res 2020; 53:2498-2509. [PMID: 33035055 DOI: 10.1021/acs.accounts.0c00407] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
ConspectusAerosol particles represent unique chemical environments because of their high surface area-to-volume ratio that promotes the effects of interfacial chemistry in confined environments. Properties such as viscosity, diffusivity, water content, pH, and morphology-following liquid-liquid phase separation-can strongly alter how a particle interacts with condensable vapors and reactive trace gases, thus modifying its continual evolution and environmental effects. Our understanding of this chemical evolution of atmospheric particulate matter and its environmental impacts is largely limited by our ability to directly observe how these critical particle properties respond to the addition or reactive uptake of new chemical components. Aerosol optical tweezers (AOT) stably trap particles in focused laser beams, providing positional control and the retrieval of many of these critical properties required to understand and predict the chemistry of aerosolized microdroplets. The analytical power of the AOT stems from the retrieval of the cavity-enhanced Raman spectrum induced by the trapping laser. Analysis of the whispering gallery modes (WGMs) that resonate as a standing wave around the droplet's interface, provide high accuracy measurements of the droplet's size, refractive index (and thus a measurement of composition), and can distinguish between core-shell, partially engulfed, and homogeneous morphologies. We have advanced the ability to determine the properties of the core and shell phases in biphasic droplets, including obtaining high-accuracy pH measurements. These capabilities were applied to perform AOT physical chemistry experiments on authentic secondary organic aerosol (SOA) produced directly in the AOT chamber by ozonolysis of terpene vapors. The propensity of the SOA to phase separate as a shell from a wide range of nonpolar to polar core phases was observed, along with the discovery of a stable emulsified state of SOA particles in an aqueous salt droplet. Micron-thick SOA shells did not impede the gain or loss of water or squalane from the core to the surrounding air, indicating no significant diffusional limitations to condensational growth or partitioning even under dry conditions. These experiments formed the foundation of a new framework that predicts how the phase-separated morphology of complex aerosols containing organic carbon evolves during continual atmospheric oxidation processes. Increases in oxidation state will quickly drive conversion from a partially engulfed to core-shell morphology that has dramatically different chemical reactivity since the core phase is completely concealed by the shell. The recent advances in the experimental capabilities of the AOT technique such as presented here enable novel experimental methodologies that provide insights into the chemistry and multidimensional properties of aerosol microdroplets, and how these coevolve and respond to continual chemical reactions.
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Affiliation(s)
- Ryan C. Sullivan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Hallie Boyer-Chelmo
- Department of Mechanical Engineering, University of North Dakota, Grand Forks, North Dakota 58202, United States
| | - Kyle Gorkowski
- Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Hassan Beydoun
- Atmospheric, Earth, & Energy Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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8
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Wolf MJ, Zhang Y, Zawadowicz MA, Goodell M, Froyd K, Freney E, Sellegri K, Rösch M, Cui T, Winter M, Lacher L, Axisa D, DeMott PJ, Levin EJT, Gute E, Abbatt J, Koss A, Kroll JH, Surratt JD, Cziczo DJ. A biogenic secondary organic aerosol source of cirrus ice nucleating particles. Nat Commun 2020; 11:4834. [PMID: 33004794 PMCID: PMC7529764 DOI: 10.1038/s41467-020-18424-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 08/20/2020] [Indexed: 11/12/2022] Open
Abstract
Atmospheric ice nucleating particles (INPs) influence global climate by altering cloud formation, lifetime, and precipitation efficiency. The role of secondary organic aerosol (SOA) material as a source of INPs in the ambient atmosphere has not been well defined. Here, we demonstrate the potential for biogenic SOA to activate as depositional INPs in the upper troposphere by combining field measurements with laboratory experiments. Ambient INPs were measured in a remote mountaintop location at -46 °C and an ice supersaturation of 30% with concentrations ranging from 0.1 to 70 L-1. Concentrations of depositional INPs were positively correlated with the mass fractions and loadings of isoprene-derived secondary organic aerosols. Compositional analysis of ice residuals showed that ambient particles with isoprene-derived SOA material can act as depositional ice nuclei. Laboratory experiments further demonstrated the ability of isoprene-derived SOA to nucleate ice under a range of atmospheric conditions. We further show that ambient concentrations of isoprene-derived SOA can be competitive with other INP sources. This demonstrates that isoprene and potentially other biogenically-derived SOA materials could influence cirrus formation and properties.
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Affiliation(s)
- Martin J Wolf
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 54-918, Cambridge, MA, 02139, USA
| | - Yue Zhang
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 135 Dauer Drive, 166 Rosenau Hall, Chapel Hill, NC, 27599, USA
- Aerodyne Research Incorporated, Center for Aerosol and Cloud Chemistry, 45 Manning Road,, Billerica, MA, 01821, USA
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA, 02467, USA
- Department of Atmospheric Sciences, Texas A&M University, 3150 TAMU, College Station, Texas, 77843, USA
| | - Maria A Zawadowicz
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 54-918, Cambridge, MA, 02139, USA
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99354, USA
| | - Megan Goodell
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 54-918, Cambridge, MA, 02139, USA
| | - Karl Froyd
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO, 80305, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, 80309, USA
| | - Evelyn Freney
- Université Clermont Auvergne, CNRS, Laboratoire de Météorologie Physique (LaMP), F-63000, Clermont-Ferrand, France
| | - Karine Sellegri
- Université Clermont Auvergne, CNRS, Laboratoire de Météorologie Physique (LaMP), F-63000, Clermont-Ferrand, France
| | - Michael Rösch
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 54-918, Cambridge, MA, 02139, USA
- Institute for Atmospheric and Climate Science, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Tianqu Cui
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 135 Dauer Drive, 166 Rosenau Hall, Chapel Hill, NC, 27599, USA
- Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, Villigen, Switzerland
| | - Margaux Winter
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 135 Dauer Drive, 166 Rosenau Hall, Chapel Hill, NC, 27599, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Larissa Lacher
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-AAF), Eggenstein-Leopoldshafen, Germany
| | - Duncan Axisa
- Droplet Measurement Technologies, Longmont, CO, 80503, USA
| | - Paul J DeMott
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - Ezra J T Levin
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523, USA
- Handix Scientific, Boulder, CO, 20854, USA
| | - Ellen Gute
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | - Jonathan Abbatt
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | - Abigail Koss
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-290, Cambridge, MA, 02139, USA
- Tofwerk USA, 2760 29th St., Boulder, CO, 80301, USA
| | - Jesse H Kroll
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-290, Cambridge, MA, 02139, USA
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 66-350, Cambridge, MA, 02139, USA
| | - Jason D Surratt
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 135 Dauer Drive, 166 Rosenau Hall, Chapel Hill, NC, 27599, USA
- Department of Chemistry, University of North Carolina at Chapel Hill, 125 South Road, Chapel Hill, North Carolina, 27599, USA
| | - Daniel J Cziczo
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 135 Dauer Drive, 166 Rosenau Hall, Chapel Hill, NC, 27599, USA.
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 66-350, Cambridge, MA, 02139, USA.
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN, 47907, USA.
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9
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Schmedding R, Rasool QZ, Zhang Y, Pye HOT, Zhang H, Chen Y, Surratt JD, Lopez-Hilfiker FD, Thornton JA, Goldstein AH, Vizuete W. Predicting secondary organic aerosol phase state and viscosity and its effect on multiphase chemistry in a regional-scale air quality model. ATMOSPHERIC CHEMISTRY AND PHYSICS 2020; 20:8201-8225. [PMID: 32983235 PMCID: PMC7510956 DOI: 10.5194/acp-20-8201-2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Atmospheric aerosols are a significant public health hazard and have substantial impacts on the climate. Secondary organic aerosols (SOAs) have been shown to phase separate into a highly viscous organic outer layer surrounding an aqueous core. This phase separation can decrease the partitioning of semi-volatile and low-volatile species to the organic phase and alter the extent of acid-catalyzed reactions in the aqueous core. A new algorithm that can determine SOA phase separation based on their glass transition temperature (T g), oxygen to carbon (O : C) ratio and organic mass to sulfate ratio, and meteorological conditions was implemented into the Community Multiscale Air Quality Modeling (CMAQ) system version 5.2.1 and was used to simulate the conditions in the continental United States for the summer of 2013. SOA formed at the ground/surface level was predicted to be phase separated with core-shell morphology, i.e., aqueous inorganic core surrounded by organic coating 65.4 % of the time during the 2013 Southern Oxidant and Aerosol Study (SOAS) on average in the isoprene-rich southeastern United States. Our estimate is in proximity to the previously reported ~ 70 % in literature. The phase states of organic coatings switched between semi-solid and liquid states, depending on the environmental conditions. The semi-solid shell occurring with lower aerosol liquid water content (western United States and at higher altitudes) has a viscosity that was predicted to be 102-1012 Pa s, which resulted in organic mass being decreased due to diffusion limitation. Organic aerosol was primarily liquid where aerosol liquid water was dominant (eastern United States and at the surface), with a viscosity < 102 Pa s. Phase separation while in a liquid phase state, i.e., liquid-liquid phase separation (LLPS), also reduces reactive uptake rates relative to homogeneous internally mixed liquid morphology but was lower than aerosols with a thick viscous organic shell. The sensitivity cases performed with different phase-separation parameterization and dissolution rate of isoprene epoxydiol (IEPOX) into the particle phase in CMAQ can have varying impact on fine particulate matter (PM2.5) organic mass, in terms of bias and error compared to field data collected during the 2013 SOAS. This highlights the need to better constrain the parameters that govern phase state and morphology of SOA, as well as expand mechanistic representation of multiphase chemistry for non-IEPOX SOA formation in models aided by novel experimental insights.
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Affiliation(s)
- Ryan Schmedding
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Quazi Z. Rasool
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Yue Zhang
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
- Aerodyne Research, Inc., Billerica, MA 01821, USA
| | - Havala O. T. Pye
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
- Office of Research and Development, Environmental Protection Agency, Research Triangle Park, Durham, NC 27709, USA
| | - Haofei Zhang
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA
| | - Yuzhi Chen
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Jason D. Surratt
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | | | - Joel A. Thornton
- Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195, USA
| | - Allen H. Goldstein
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA
| | - William Vizuete
- Department of Environmental Science and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
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10
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Evoy E, Kamal S, Patey GN, Martin ST, Bertram AK. Unified Description of Diffusion Coefficients from Small to Large Molecules in Organic-Water Mixtures. J Phys Chem A 2020; 124:2301-2308. [PMID: 32078327 DOI: 10.1021/acs.jpca.9b11271] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Diffusion coefficients in mixtures of organic molecules and water are needed for many applications, ranging from the environmental modeling of pollutant transport, air quality, and climate, to improving the stability of foods, biomolecules, and pharmaceutical agents for longer use and storage. The Stokes-Einstein relation has been successful for predicting diffusion coefficients of large molecules in organic-water mixtures from viscosity, yet it routinely underpredicts, by orders of magnitude, the diffusion coefficients of small molecules in organic-water mixtures. Herein, a unified description of diffusion coefficients of large and small molecules in organic-water mixtures, based on the fractional Stokes-Einstein relation, is presented. A fractional Stokes-Einstein relation is able to describe 98% of the observed diffusion coefficients from small to large molecules, roughly within the uncertainties of the measurements. The data set used in the analysis includes a wide range of radii of diffusing molecules, viscosities, and intermolecular interactions. As a case study, we show that the degradation of polycyclic aromatic hydrocarbons (PAHs) by O3 within organic-water particles in the planetary boundary layer is relatively short (≲1 day) when the viscosity of the particle is ≲102 Pa s. We also show that the degradation times predicted using the Stokes-Einstein relation and the fractional Stokes-Einstein relation can differ by up to a factor of 10 in this region of the atmosphere.
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Affiliation(s)
- Erin Evoy
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1
| | - Saeid Kamal
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1
| | - Grenfell N Patey
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1
| | - Scot T Martin
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Allan K Bertram
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1
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11
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Zaveri RA, Shilling JE, Zelenyuk A, Zawadowicz MA, Suski K, China S, Bell DM, Veghte D, Laskin A. Particle-Phase Diffusion Modulates Partitioning of Semivolatile Organic Compounds to Aged Secondary Organic Aerosol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2595-2605. [PMID: 31994876 DOI: 10.1021/acs.est.9b05514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The diffusivity of semivolatile organic compounds (SVOCs) in the bulk particle phase of a viscous atmospheric secondary organic aerosol (SOA) can have a profound impact on aerosol growth and size distribution dynamics. Here, we investigate the bulk diffusivity of SVOCs formed from photo-oxidation of isoprene as they partition to a bimodal aerosol consisting of an Aitken (potassium sulfate) and accumulation mode (aged α-pinene SOA) particles as a function of relative humidity (RH). The model analysis of the observed size distribution evolution shows that liquid-like diffusion coefficient values of Db > 10-10 cm2 s-1 fail to explain the growth of the Aitken mode. Instead, much lower values of Db between 2.5 × 10-15 cm2 s-1 at 32% RH and 8 × 10-15 cm2 s-1 at 82% RH were needed to successfully reproduce the growth of both modes. The diffusivity within the aged α-pinene SOA remains appreciably slow even at 80% RH, resulting in hindered partitioning of SVOCs to large viscous particles and allowing smaller and relatively less viscous particles to effectively absorb the available SVOCs and grow much faster than would be possible otherwise. These results have important implications for modeling SOA formation and growth in the ambient atmosphere.
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Affiliation(s)
- Rahul A Zaveri
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - John E Shilling
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Alla Zelenyuk
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Maria A Zawadowicz
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Kaitlyn Suski
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Swarup China
- William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - David M Bell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Daniel Veghte
- William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Alexander Laskin
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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12
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Pospisilova V, Lopez-Hilfiker FD, Bell DM, El Haddad I, Mohr C, Huang W, Heikkinen L, Xiao M, Dommen J, Prevot ASH, Baltensperger U, Slowik JG. On the fate of oxygenated organic molecules in atmospheric aerosol particles. SCIENCE ADVANCES 2020; 6:eaax8922. [PMID: 32201715 PMCID: PMC7069715 DOI: 10.1126/sciadv.aax8922] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 12/17/2019] [Indexed: 05/05/2023]
Abstract
Highly oxygenated organic molecules (HOMs) are formed from the oxidation of biogenic and anthropogenic gases and affect Earth's climate and air quality by their key role in particle formation and growth. While the formation of these molecules in the gas phase has been extensively studied, the complexity of organic aerosol (OA) and lack of suitable measurement techniques have hindered the investigation of their fate post-condensation, although further reactions have been proposed. We report here novel real-time measurements of these species in the particle phase, achieved using our recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Our results reveal that condensed-phase reactions rapidly alter OA composition and the contribution of HOMs to the particle mass. In consequence, the atmospheric fate of HOMs cannot be described solely in terms of volatility, but particle-phase reactions must be considered to describe HOM effects on the overall particle life cycle and global carbon budget.
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Affiliation(s)
- V. Pospisilova
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - F. D. Lopez-Hilfiker
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Tofwerk AG, 3600 Thun, Switzerland
| | - D. M. Bell
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - I. El Haddad
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - C. Mohr
- Department of Environmental Science, Stockholm University, Stockholm 11418, Sweden
| | - W. Huang
- Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - L. Heikkinen
- Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki 00014, Finland
| | - M. Xiao
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - J. Dommen
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - A. S. H. Prevot
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - U. Baltensperger
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - J. G. Slowik
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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13
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Song YC, Ingram S, Arbon RE, Topping DO, Glowacki DR, Reid JP. Transient cavity dynamics and divergence from the Stokes-Einstein equation in organic aerosol. Chem Sci 2020; 11:2999-3006. [PMID: 34122802 PMCID: PMC8157714 DOI: 10.1039/c9sc06228a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/15/2020] [Indexed: 12/26/2022] Open
Abstract
The diffusion of small molecules through viscous matrices formed by large organic molecules is important across a range of domains, including pharmaceutical science, materials chemistry, and atmospheric science, impacting on, for example, the formation of amorphous and crystalline phases. Here we report significant breakdowns in the Stokes-Einstein (SE) equation from measurements of the diffusion of water (spanning 5 decades) and viscosity (spanning 12 decades) in saccharide aerosol droplets. Molecular dynamics simulations show water diffusion is not continuous, but proceeds by discrete hops between transient cavities that arise and dissipate as a result of dynamical fluctuations within the saccharide lattice. The ratio of transient cavity volume to solvent volume increases with size of molecules making up the lattice, increasing divergence from SE predictions. This improved mechanistic understanding of diffusion in viscous matrices explains, for example, why organic compounds equilibrate according to SE predictions and water equilibrates more rapidly in aerosols.
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Affiliation(s)
- Young-Chul Song
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Stephen Ingram
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
- Centre for Computational Chemistry, University of Bristol Cantock's Close BS8 1TS UK
| | - Robert E Arbon
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
- Centre for Computational Chemistry, University of Bristol Cantock's Close BS8 1TS UK
| | - David O Topping
- School of Earth and Environmental Science, University of Manchester Manchester M13 9PL UK
| | - David R Glowacki
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
- Centre for Computational Chemistry, University of Bristol Cantock's Close BS8 1TS UK
- Department of Computer Science, University of Bristol UK
| | - Jonathan P Reid
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
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14
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Zhang Y, Nichman L, Spencer P, Jung JI, Lee A, Heffernan BK, Gold A, Zhang Z, Chen Y, Canagaratna MR, Jayne JT, Worsnop DR, Onasch TB, Surratt JD, Chandler D, Davidovits P, Kolb CE. The Cooling Rate- and Volatility-Dependent Glass-Forming Properties of Organic Aerosols Measured by Broadband Dielectric Spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12366-12378. [PMID: 31490675 DOI: 10.1021/acs.est.9b03317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Glass transitions of secondary organic aerosols (SOA) from liquid/semisolid to solid phase states have important implications for aerosol reactivity, growth, and cloud formation properties. In the present study, glass transition temperatures (Tg) of isoprene SOA components, including isoprene hydroxy hydroperoxide (ISOPOOH), isoprene-derived epoxydiols (IEPOX), 2-methyltetrols, and 2-methyltetrol sulfates, were measured at atmospherically relevant cooling rates (2-10 K/min) by thin film broadband dielectric spectroscopy. The results indicate that 2-methyltetrol sulfates have the highest glass transition temperature, while ISOPOOH has the lowest glass transition temperature. By varying the cooling rate of the same compound from 2 to 10 K/min, the Tg of these compounds increased by 4-5 K. This temperature difference leads to a height difference of 400-800 m in the atmosphere for the corresponding updraft induced cooling rates, assuming a hygroscopicity value (κ) of 0.1 and relative humidity less than 95%. The Tg of the organic compounds was found to be strongly correlated with volatility, and a semiempirical formula between glass transition temperatures and volatility was derived. The Gordon-Taylor equation was applied to calculate the effect of relative humidity (RH) and water content at five mixing ratios on the Tg of organic aerosols. The model shows that Tg could drop by 15-40 K as the RH changes from <5 to 90%, whereas the mixing ratio of water in the particle increases from 0 to 0.5. These results underscore the importance of chemical composition, updraft rates, and water content (RH) in determining the phase states and hygroscopic properties of organic particles.
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Affiliation(s)
- Yue Zhang
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 , United States
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Leonid Nichman
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Peyton Spencer
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Jason I Jung
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Andrew Lee
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Brian K Heffernan
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Avram Gold
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Zhenfa Zhang
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Yuzhi Chen
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | | | - John T Jayne
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 , United States
| | - Douglas R Worsnop
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 , United States
| | - Timothy B Onasch
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 , United States
| | - Jason D Surratt
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - David Chandler
- Department of Chemistry , University of California, Berkeley , Berkeley , California 94720 , United States
| | - Paul Davidovits
- Department of Chemistry , Boston College , Chestnut Hill , Massachusetts 02459 , United States
| | - Charles E Kolb
- Aerodyne Research Inc. , Billerica , Massachusetts 01821 , United States
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15
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Slade JH, Ault AP, Bui AT, Ditto JC, Lei Z, Bondy AL, Olson NE, Cook RD, Desrochers SJ, Harvey RM, Erickson MH, Wallace HW, Alvarez SL, Flynn JH, Boor BE, Petrucci GA, Gentner DR, Griffin RJ, Shepson PB. Bouncier Particles at Night: Biogenic Secondary Organic Aerosol Chemistry and Sulfate Drive Diel Variations in the Aerosol Phase in a Mixed Forest. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4977-4987. [PMID: 31002496 DOI: 10.1021/acs.est.8b07319] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Aerosol phase state is critical for quantifying aerosol effects on climate and air quality. However, significant challenges remain in our ability to predict and quantify phase state during its evolution in the atmosphere. Herein, we demonstrate that aerosol phase (liquid, semisolid, solid) exhibits a diel cycle in a mixed forest environment, oscillating between a viscous, semisolid phase state at night and liquid phase state with phase separation during the day. The viscous nighttime particles existed despite higher relative humidity and were independently confirmed by bounce factor measurements and atomic force microscopy. High-resolution mass spectrometry shows the more viscous phase state at night is impacted by the formation of terpene-derived and higher molecular weight secondary organic aerosol (SOA) and smaller inorganic sulfate mass fractions. Larger daytime particulate sulfate mass fractions, as well as a predominance of lower molecular weight isoprene-derived SOA, lead to the liquid state of the daytime particles and phase separation after greater uptake of liquid water, despite the lower daytime relative humidity. The observed diel cycle of aerosol phase should provoke rethinking of the SOA atmospheric lifecycle, as it suggests diurnal variability in gas-particle partitioning and mixing time scales, which influence aerosol multiphase chemistry, lifetime, and climate impacts.
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Affiliation(s)
- Jonathan H Slade
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Andrew P Ault
- Department of Environmental Health Sciences , University of Michigan , Ann Arbor , Michigan 48109 , United States
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Alexander T Bui
- Department of Civil and Environmental Engineering , Rice University , Houston , Texas 77005 , United States
| | - Jenna C Ditto
- Department of Chemical and Environmental Engineering , Yale University , New Haven , Connecticut 06520 , United States
| | - Ziying Lei
- Department of Environmental Health Sciences , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Amy L Bondy
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Nicole E Olson
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Ryan D Cook
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Sarah J Desrochers
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Rebecca M Harvey
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Matthew H Erickson
- Department of Earth and Atmospheric Sciences , University of Houston , Houston , Texas 77204 , United States
| | - Henry W Wallace
- Department of Civil and Environmental Engineering , Rice University , Houston , Texas 77005 , United States
| | - Sergio L Alvarez
- Department of Earth and Atmospheric Sciences , University of Houston , Houston , Texas 77204 , United States
| | - James H Flynn
- Department of Earth and Atmospheric Sciences , University of Houston , Houston , Texas 77204 , United States
| | - Brandon E Boor
- Lyles School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Giuseppe A Petrucci
- Department of Chemistry , University of Vermont , Burlington , Vermont 05405 , United States
| | - Drew R Gentner
- Department of Chemical and Environmental Engineering , Yale University , New Haven , Connecticut 06520 , United States
| | - Robert J Griffin
- Department of Civil and Environmental Engineering , Rice University , Houston , Texas 77005 , United States
- Department of Chemical and Biomolecular Engineering , Rice University , Houston , Texas 77005 , United States
| | - Paul B Shepson
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
- Department of Earth, Atmospheric and Planetary Sciences , Purdue University , West Lafayette , Indiana 47907 , United States
- Purdue Climate Change Research Center , Purdue University , West Lafayette , Indiana 47907 , United States
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16
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Ye Q, Sullivan RC, Donahue NM. Using Ionic Liquids To Study the Migration of Semivolatile Organic Vapors in Smog Chamber Experiments. J Phys Chem A 2019; 123:3887-3892. [PMID: 30950612 DOI: 10.1021/acs.jpca.9b02847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atmospheric organic aerosols comprise complex mixtures of a myriad of compounds with a wide range of structures and volatilities. To understand the fate of atmospheric organic aerosols and their contribution to particulate matter pollution, we need to study the relative portion divided between semivolatile organic compounds (SVOCs) and low-volatility organic compounds (LVOCs). SVOCs can effectively migrate and exchange between aerosol populations and thus are more accessible for further reactions and removal processes, while LVOCs will essentially stay in the particle phase. Here, we introduce using ionic liquid droplets as novel sorbents for organic vapors in smog chamber experiments to study the transfer of constituents between aerosol populations and to separate SVOCs and LVOCs from chamber-produced secondary organic aerosols (SOAs). SOA was formed and condensed on the ammonium-sulfate seeds, and later ionic liquid droplets were introduced into the chamber. We show that there are considerable yields of both LVOCs and SVOCs produced from α-pinene ozonolysis, and the uptake of SVOCs into the ionic liquid increases as the amount of reacted α-pinene increases. We also show that the SVOCs absorbed into the ionic liquid re-evaporate more readily compared to SOA originally condensed on the ammonium-sulfate seeds. We are thus able to differentiate the semivolatile components that partition into the extremely polar ionic liquid aerosols from the demonstrably less volatile components also condensed on the ammonium-sulfate seeds. Combined with previous studies using other organic aerosols as solvents to probe SVOC transfer between aerosol populations, we provide a wide set of measurements to probe and constrain the physical and thermodynamic properties of chamber-produced SOA complex.
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Affiliation(s)
- Qing Ye
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Ryan C Sullivan
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Neil M Donahue
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
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17
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Wallace BJ, Preston TC. Water Uptake and Loss in Viscous Aerosol Particles with Concentration-Dependent Diffusivities. J Phys Chem A 2019; 123:3374-3382. [PMID: 30901522 DOI: 10.1021/acs.jpca.9b00907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An accurate understanding of the equilibration timescale of organic aerosol particles with surrounding water vapor is difficult because of the strong concentration-dependent diffusivities that are present in these systems. We examine this problem along with the closely related problem of the time-dependent radius of a binary aerosol particle during the uptake or loss of water. The governing equations and boundary conditions are discussed and a boundary value problem is formulated and solved. The resulting expressions are applied to water uptake and loss in two systems of atmospheric importance: aqueous-inorganic particles and high-viscosity organic particles. Accuracy is evaluated through a comparison with numerical solutions. For particles whose diffusivity has a strong dependence on water concentration and whose viscosity remains above 1 Pa·s during water uptake or loss, the expression for the characteristic equilibration time is found to be in excellent agreement with numerical results. Moreover, it provides physical insights into mass transport processes.
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Affiliation(s)
- Brandon J Wallace
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry , McGill University , 805 Sherbrooke Street West , Montreal , H3A 0B9 Québec , Canada
| | - Thomas C Preston
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry , McGill University , 805 Sherbrooke Street West , Montreal , H3A 0B9 Québec , Canada
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18
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Rovelli G, Song YC, Maclean AM, Topping DO, Bertram AK, Reid JP. Comparison of Approaches for Measuring and Predicting the Viscosity of Ternary Component Aerosol Particles. Anal Chem 2019; 91:5074-5082. [PMID: 30921513 DOI: 10.1021/acs.analchem.8b05353] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Measurements of the water activity-dependent viscosity of aerosol particles from two techniques are compared, specifically from the coalescence of two droplets in holographic optical tweezers (HOT) and poke-and-flow experiments on particles deposited onto a glass substrate. These new data are also compared with the fitting of dimer coagulation, isolation, and coalescence (DCIC) measurements. The aerosol system considered in this work are ternary mixtures of sucrose-citric acid-water and sucrose-NaNO3-water, at varying solute mass ratios. Results from HOT and poke-and-flow are in excellent agreement over their overlapping range of applicability (∼103-107 Pa s); fitted curves from DCIC data show variable agreement with the other two techniques because of the sensitivity of the applied modeling framework to the representation of water content in the particles. Further, two modeling approaches for the predictions of the water activity-dependent viscosity of these ternary systems are evaluated. We show that it is possible to represent their viscosity with relatively simple mixing rules applied to the subcooled viscosity values of each component or to the viscosity of the corresponding binary mixtures.
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Affiliation(s)
- Grazia Rovelli
- School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
| | - Young-Chul Song
- School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
| | - Adrian M Maclean
- Department of Chemistry , University of British Columbia , Vancouver , BC V6T 1Z1 , Canada
| | - David O Topping
- School of Earth, Atmospheric and Environmental Science , University of Manchester , Manchester M13 9PL , U.K
| | - Allan K Bertram
- Department of Chemistry , University of British Columbia , Vancouver , BC V6T 1Z1 , Canada
| | - Jonathan P Reid
- School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
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19
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Marsh A, Rovelli G, Song YC, Pereira KL, Willoughby RE, Bzdek BR, Hamilton JF, Orr-Ewing AJ, Topping DO, Reid JP. Accurate representations of the physicochemical properties of atmospheric aerosols: when are laboratory measurements of value? Faraday Discuss 2018; 200:639-661. [PMID: 28574570 DOI: 10.1039/c7fd00008a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Laboratory studies can provide important insights into the processes that occur at the scale of individual particles in ambient aerosol. We examine the accuracies of measurements of core physicochemical properties of aerosols that can be made in single particle studies and explore the impact of these properties on the microscopic processes that occur in ambient aerosol. Presenting new measurements, we examine here the refinements in our understanding of aerosol hygroscopicity, surface tension, viscosity and optical properties that can be gained from detailed laboratory measurements for complex mixtures through to surrogates for secondary organic atmospheric aerosols.
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20
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Arroyo PC, Malecha KT, Ammann M, Nizkorodov SA. Influence of humidity and iron(iii) on photodegradation of atmospheric secondary organic aerosol particles. Phys Chem Chem Phys 2018; 20:30021-30031. [PMID: 30480278 DOI: 10.1039/c8cp03981j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The absorption of solar actinic radiation by atmospheric secondary organic aerosol (SOA) particles drives condensed-phase photochemical processes, which lead to particle mass loss by the production of CO, CO2, hydrocarbons, and various oxygenated volatile organic compounds (OVOCs). We examined the influence of relative humidity (RH) and Fe(iii) content on the OVOC release and subsequent mass loss from secondary organic aerosol material (SOM) during UV irradiation. The samples were generated in a flow tube reactor from the oxidation of d-limonene by ozone. The SOM was collected with a Micro Orifice Uniform Deposit Impactor (MOUDI) on CaF2 windows. To selected samples, a variable amount of FeCl3 was added before irradiation. The resulting SOM samples, with or without added FeCl3, were irradiated with a 305 nm light-emitting diode and the release of several OVOCs, including acetic acid, acetone, formic acid and acetaldehyde, was measured with a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). The release of OVOCs from photodegradation of SOM at typical ambient mid-values of RH (30-70%) was 2-4 times higher than under dry conditions. The release of OVOCs was slightly enhanced in the presence of low concentrations of iron (0.04 Fe molar ratio) but it was suppressed at higher concentrations (0.50 Fe molar ratio) of iron indicating the existence of a complicated radical chemistry driving the photodegradation of SOM. Our findings suggest that the presence of iron in atmospheric aerosol particles will either increase or decrease release of OVOCs due to the photodegradation of SOM depending on whether the relative iron concentration is low or high, respectively. At atmospherically relevant RH conditions, the expected fractional mass loss induced by these photochemical processes from limonene SOA particles would be between 2 and 4% of particle mass per hour. Therefore, photodegradation is an important aging mechanism for this type of SOA.
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Affiliation(s)
- Pablo Corral Arroyo
- Paul Scherrer Institute, Laboratory of Environmental Chemistry, 5232 Villigen PSI, Switzerland
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21
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Resolving the mechanisms of hygroscopic growth and cloud condensation nuclei activity for organic particulate matter. Nat Commun 2018; 9:4076. [PMID: 30287821 PMCID: PMC6172236 DOI: 10.1038/s41467-018-06622-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 09/14/2018] [Indexed: 12/02/2022] Open
Abstract
Hygroscopic growth and cloud condensation nuclei activation are key processes for accurately modeling the climate impacts of organic particulate matter. Nevertheless, the microphysical mechanisms of these processes remain unresolved. Here we report complex thermodynamic behaviors, including humidity-dependent hygroscopicity, diameter-dependent cloud condensation nuclei activity, and liquid–liquid phase separation in the laboratory for biogenically derived secondary organic material representative of similar atmospheric organic particulate matter. These behaviors can be explained by the non-ideal mixing of water with hydrophobic and hydrophilic organic components. The non-ideality-driven liquid–liquid phase separation further enhances water uptake and induces lowered surface tension at high relative humidity, which result in a lower barrier to cloud condensation nuclei activation. By comparison, secondary organic material representing anthropogenic sources does not exhibit complex thermodynamic behavior. The combined results highlight the importance of detailed thermodynamic representations of the hygroscopicity and cloud condensation nuclei activity in models of the Earth’s climate system. The interactions between organic particulate matter and water vapour affect climate predictions, yet the mechanisms of these interactions remain unresolved. Here, the authors propose a phase separation mechanism that reconciles the observed hygroscopicity and cloud condensation nuclei activity.
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22
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Wang Y, Liu P, Li YJ, Bateman AP, Martin ST, Hung HM. The Reactivity of Toluene-Derived Secondary Organic Material with Ammonia and the Influence of Water Vapor. J Phys Chem A 2018; 122:7739-7747. [DOI: 10.1021/acs.jpca.8b06685] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yan Wang
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts United States
| | | | - Yong Jie Li
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | | | | | - Hui-Ming Hung
- Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan
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23
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Reid JP, Bertram AK, Topping DO, Laskin A, Martin ST, Petters MD, Pope FD, Rovelli G. The viscosity of atmospherically relevant organic particles. Nat Commun 2018; 9:956. [PMID: 29511168 PMCID: PMC5840428 DOI: 10.1038/s41467-018-03027-z] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/12/2018] [Indexed: 11/13/2022] Open
Abstract
The importance of organic aerosol particles in the environment has been long established, influencing cloud formation and lifetime, absorbing and scattering sunlight, affecting atmospheric composition and impacting on human health. Conventionally, ambient organic particles were considered to exist as liquids. Recent observations in field measurements and studies in the laboratory suggest that they may instead exist as highly viscous semi-solids or amorphous glassy solids under certain conditions, with important implications for atmospheric chemistry, climate and air quality. This review explores our understanding of aerosol particle phase, particularly as identified by measurements of the viscosity of organic particles, and the atmospheric implications of phase state.
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Affiliation(s)
- Jonathan P Reid
- School of Chemistry, University of Bristol, Manchester, BS8 1TS, UK.
| | - Allan K Bertram
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | - David O Topping
- School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, UK
| | - Alexander Laskin
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Scot T Martin
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Markus D Petters
- Department of Marine Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, 27695, USA
| | - Francis D Pope
- School of Geography, Earth and Environmental Sciences, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK
| | - Grazia Rovelli
- School of Chemistry, University of Bristol, Manchester, BS8 1TS, UK
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Liu P, Li YJ, Wang Y, Bateman AP, Zhang Y, Gong Z, Bertram AK, Martin ST. Highly Viscous States Affect the Browning of Atmospheric Organic Particulate Matter. ACS CENTRAL SCIENCE 2018; 4. [PMID: 29532020 PMCID: PMC5832997 DOI: 10.1021/acscentsci.7b00452] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Initially transparent organic particulate matter (PM) can become shades of light-absorbing brown via atmospheric particle-phase chemical reactions. The production of nitrogen-containing compounds is one important pathway for browning. Semisolid or solid physical states of organic PM might, however, have sufficiently slow diffusion of reactant molecules to inhibit browning reactions. Herein, organic PM of secondary organic material (SOM) derived from toluene, a common SOM precursor in anthropogenically affected environments, was exposed to ammonia at different values of relative humidity (RH). The production of light-absorbing organonitrogen imines from ammonia exposure, detected by mass spectrometry and ultraviolet-visible spectrophotometry, was kinetically inhibited for RH < 20% for exposure times of 6 min to 24 h. By comparison, from 20% to 60% RH organonitrogen production took place, implying ammonia uptake and reaction. Correspondingly, the absorption index k across 280 to 320 nm increased from 0.012 to 0.02, indicative of PM browning. The k value across 380 to 420 nm increased from 0.001 to 0.004. The observed RH-dependent behavior of ammonia uptake and browning was well captured by a model that considered the diffusivities of both the large organic molecules that made up the PM and the small reactant molecules taken up from the gas phase into the PM. Within the model, large-molecule diffusivity was calculated based on observed SOM viscosity and evaporation. Small-molecule diffusivity was represented by the water diffusivity measured by a quartz-crystal microbalance. The model showed that the browning reaction rates at RH < 60% could be controlled by the low diffusivity of the large organic molecules from the interior region of the particle to the reactive surface region. The results of this study have implications for accurate modeling of atmospheric brown carbon production and associated influences on energy balance.
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Affiliation(s)
- Pengfei Liu
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yong Jie Li
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department
of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Yan Wang
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- T. H.
Chan School of Public Health, Harvard University, Boston, Massachusetts 02115, United States
| | - Adam P. Bateman
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yue Zhang
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Aerodyne
Research Inc., Billerica, Massachusetts 01821, United States
| | - Zhaoheng Gong
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Allan K. Bertram
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scot T. Martin
- John A. Paulson School of Engineering and Applied
Sciences and Department
of Earth and
Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- E-mail:
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26
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Marshall FH, Berkemeier T, Shiraiwa M, Nandy L, Ohm PB, Dutcher CS, Reid JP. Influence of particle viscosity on mass transfer and heterogeneous ozonolysis kinetics in aqueous–sucrose–maleic acid aerosol. Phys Chem Chem Phys 2018; 20:15560-15573. [DOI: 10.1039/c8cp01666f] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ozonolysis kinetics of viscous aerosol particles containing maleic acid are studied. Kinetic fits are constrained by measured particle viscosities.
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Affiliation(s)
| | - Thomas Berkemeier
- School of Chemical & Biomolecular Engineering
- Georgia Institute of Technology
- Atlanta
- USA
| | | | - Lucy Nandy
- Department of Mechanical Engineering
- University of Minnesota
- Minneapolis
- USA
| | - Peter B. Ohm
- Department of Mechanical Engineering
- University of Minnesota
- Minneapolis
- USA
| | - Cari S. Dutcher
- Department of Mechanical Engineering
- University of Minnesota
- Minneapolis
- USA
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27
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Bzdek BR, Reid JP. Perspective: Aerosol microphysics: From molecules to the chemical physics of aerosols. J Chem Phys 2017; 147:220901. [DOI: 10.1063/1.5002641] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Bryan R. Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
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28
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Pfrang C, Rastogi K, Cabrera-Martinez ER, Seddon AM, Dicko C, Labrador A, Plivelic TS, Cowieson N, Squires AM. Complex three-dimensional self-assembly in proxies for atmospheric aerosols. Nat Commun 2017; 8:1724. [PMID: 29170428 PMCID: PMC5701067 DOI: 10.1038/s41467-017-01918-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 10/25/2017] [Indexed: 01/23/2023] Open
Abstract
Aerosols are significant to the Earth’s climate, with nearly all atmospheric aerosols containing organic compounds that often contain both hydrophilic and hydrophobic parts. However, the nature of how these compounds are arranged within an aerosol droplet remains unknown. Here we demonstrate that fatty acids in proxies for atmospheric aerosols self-assemble into highly ordered three-dimensional nanostructures that may have implications for environmentally important processes. Acoustically trapped droplets of oleic acid/sodium oleate mixtures in sodium chloride solution are analysed by simultaneous synchrotron small-angle X-ray scattering and Raman spectroscopy in a controlled gas-phase environment. We demonstrate that the droplets contained crystal-like lyotropic phases including hexagonal and cubic close-packed arrangements of spherical and cylindrical micelles, and stacks of bilayers, whose structures responded to atmospherically relevant humidity changes and chemical reactions. Further experiments show that self-assembly reduces the rate of the reaction of the fatty acid with ozone, and that lyotropic-phase formation also occurs in more complex mixtures more closely resembling compositions of atmospheric aerosols. We suggest that lyotropic-phase formation likely occurs in the atmosphere, with potential implications for radiative forcing, residence times and other aerosol characteristics. Nearly all atmospheric aerosols contain surface-active organic compounds; however, the nature of how they arrange remains poorly understood. Here, the authors show that fatty acids in atmospheric aerosol proxies self-assemble into highly ordered, viscous 3D nanostructures that undergo changes upon exposure to humidity and ozone.
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Affiliation(s)
- C Pfrang
- Department of Chemistry, University of Reading, Whiteknights Campus, PO Box 224, Reading, RG6 6AD, UK.
| | - K Rastogi
- Department of Chemistry, University of Reading, Whiteknights Campus, PO Box 224, Reading, RG6 6AD, UK
| | - E R Cabrera-Martinez
- Department of Chemistry, University of Reading, Whiteknights Campus, PO Box 224, Reading, RG6 6AD, UK
| | - A M Seddon
- H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.,Bristol Centre for Functional Nanomaterials, H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - C Dicko
- Pure and Applied Biochemistry, Chemical Center, University of Lund, Naturvetarvägen 14, 22241, Lund, Sweden
| | - A Labrador
- MAX IV Laboratory, University of Lund, PO Box 188, 22100, Lund, Sweden
| | - T S Plivelic
- MAX IV Laboratory, University of Lund, PO Box 188, 22100, Lund, Sweden
| | - N Cowieson
- Diamond Light Source, Harwell Science & Innovation Campus, Didcot, OX11 0DE, UK
| | - A M Squires
- Department of Chemistry, University of Reading, Whiteknights Campus, PO Box 224, Reading, RG6 6AD, UK. .,Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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29
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Preston TC, Davies JF, Wilson KR. The frequency-dependent response of single aerosol particles to vapour phase oscillations and its application in measuring diffusion coefficients. Phys Chem Chem Phys 2017; 19:3922-3931. [PMID: 28106191 DOI: 10.1039/c6cp07711k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new method for measuring diffusion in the condensed phase of single aerosol particles is proposed and demonstrated. The technique is based on the frequency-dependent response of a binary particle to oscillations in the vapour phase of one of its chemical components. We discuss how this physical situation allows for what would typically be a non-linear boundary value problem to be approximately reduced to a linear boundary value problem. For the case of aqueous aerosol particles, we investigate the accuracy of the closed-form analytical solution to this linear problem through a comparison with the numerical solution of the full problem. Then, using experimentally measured whispering gallery modes to track the frequency-dependent response of aqueous particles to relative humidity oscillations, we determine diffusion coefficients as a function of water activity. The measured diffusion coefficients are compared to previously reported values found using the two common experiments: (i) the analysis of the sorption/desorption of water from a particle after a step-wise change to the surrounding relative humidity and (ii) the isotopic exchange of water between a particle and the vapour phase. The technique presented here has two main strengths: first, when compared to the sorption/desorption experiment, it does not require the numerical evaluation of a boundary value problem during the fitting process as a closed-form expression is available. Second, when compared to the isotope exchange experiment, it does not require the use of labeled molecules. Therefore, the frequency-dependent experiment retains the advantages of these two commonly used methods but does not suffer from their drawbacks.
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Affiliation(s)
- Thomas C Preston
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry, McGill University, 805 Sherbrooke Street West, Montreal, QC, Canada H3A 0B9.
| | - James F Davies
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94611, USA
| | - Kevin R Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94611, USA
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30
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Ingram S, Cai C, Song YC, Glowacki DR, Topping DO, O’Meara S, Reid JP. Characterising the evaporation kinetics of water and semi-volatile organic compounds from viscous multicomponent organic aerosol particles. Phys Chem Chem Phys 2017; 19:31634-31646. [DOI: 10.1039/c7cp05172g] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we present methods to simultaneously investigate diffusivities and volatilities in studies of evolving single aerosol particle size and composition.
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Affiliation(s)
- Stephen Ingram
- School of Chemistry
- University of Bristol
- Bristol BS8 1TS
- UK
| | - Chen Cai
- Department of Atmospheric and Oceanic Sciences
- School of Physics
- Peking University
- Beijing 100871
- China
| | | | - David R. Glowacki
- School of Chemistry
- University of Bristol
- Bristol BS8 1TS
- UK
- Department of Computer Science
| | - David O. Topping
- School of Earth and Atmospheric Sciences
- University of Manchester
- Manchester M13 9PL
- UK
| | - Simon O’Meara
- School of Earth and Atmospheric Sciences
- University of Manchester
- Manchester M13 9PL
- UK
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31
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Zhang Y, Cai C, Pang SF, Reid JP, Zhang YH. A rapid scan vacuum FTIR method for determining diffusion coefficients in viscous and glassy aerosol particles. Phys Chem Chem Phys 2017; 19:29177-29186. [DOI: 10.1039/c7cp04473a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of glassy formation on water transport in sucrose aerosol droplets is evaluated from characteristic time in a vacuum FTIR experiment.
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Affiliation(s)
- Yun Zhang
- Institute of Chemical Physics
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | - Chen Cai
- Institute of Chemical Physics
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
- Department of Atmospheric and Oceanic Sciences
| | - Shu-Feng Pang
- Institute of Chemical Physics
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | | | - Yun-Hong Zhang
- Institute of Chemical Physics
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
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32
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Finlayson-Pitts BJ. Introductory lecture: atmospheric chemistry in the Anthropocene. Faraday Discuss 2017; 200:11-58. [DOI: 10.1039/c7fd00161d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The term “Anthropocene” was coined by Professor Paul Crutzen in 2000 to describe an unprecedented era in which anthropogenic activities are impacting planet Earth on a global scale. Greatly increased emissions into the atmosphere, reflecting the advent of the Industrial Revolution, have caused significant changes in both the lower and upper atmosphere. Atmospheric reactions of the anthropogenic emissions and of those with biogenic compounds have significant impacts on human health, visibility, climate and weather. Two activities that have had particularly large impacts on the troposphere are fossil fuel combustion and agriculture, both associated with a burgeoning population. Emissions are also changing due to alterations in land use. This paper describes some of the tropospheric chemistry associated with the Anthropocene, with emphasis on areas having large uncertainties. These include heterogeneous chemistry such as those of oxides of nitrogen and the neonicotinoid pesticides, reactions at liquid interfaces, organic oxidations and particle formation, the role of sulfur compounds in the Anthropocene and biogenic–anthropogenic interactions. A clear and quantitative understanding of the connections between emissions, reactions, deposition and atmospheric composition is central to developing appropriate cost-effective strategies for minimizing the impacts of anthropogenic activities. The evolving nature of emissions in the Anthropocene places atmospheric chemistry at the fulcrum of determining human health and welfare in the future.
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33
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Moridnejad A, Preston TC. Models of Isotopic Water Diffusion in Spherical Aerosol Particles. J Phys Chem A 2016; 120:9759-9766. [PMID: 27973801 DOI: 10.1021/acs.jpca.6b11241] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isotopic exchange experiments that utilize D2O and H2O have received attention as a method for studying water diffusion in high viscosity aerosol particles. However, the mathematical models used to retrieve diffusion coefficients from these measurements have yet to be critically examined. Here, two models for the isotopic exchange of D2O and H2O in spherical particles are analyzed and compared. The primary difference between the two models is the choice of boundary condition at the surface of the spherical particle. In one model, it is assumed that the concentration of D2O at the surface is fixed, while in the other model, it is assumed that, at the particle surface, the concentration of D2O in the condensed phase is in equilibrium with D2O vapor. Closed-form expressions for the two boundary value problems that describe these physical models are found and discussed. Then, specific examples of aqueous droplets containing either sucrose, citric acid, and shikimic acid are examined with both models. It is found that at low relative humidities the choice of boundary condition has a negligible effect on the predicted lifetime of isotopic exchange, while at high relative humidities predicted lifetimes can differ by orders of magnitude. The implication of this result is that the choice of model can greatly affect diffusion coefficients retrieved from experimental measurements under certain conditions. Finally, discrepancies between diffusion coefficients measured using isotopic exchange and water sorption and desorption experiments are discussed.
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Affiliation(s)
- Ali Moridnejad
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry, McGill University , 805 Sherbrooke Street West, Montreal, QC Canada H3A 0B9
| | - Thomas C Preston
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry, McGill University , 805 Sherbrooke Street West, Montreal, QC Canada H3A 0B9
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Abstract
Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions.
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35
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Song YC, Haddrell AE, Bzdek BR, Reid JP, Bannan T, Topping DO, Percival C, Cai C. Measurements and Predictions of Binary Component Aerosol Particle Viscosity. J Phys Chem A 2016; 120:8123-8137. [DOI: 10.1021/acs.jpca.6b07835] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Young Chul Song
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Allen E. Haddrell
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Bryan R. Bzdek
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Thomas Bannan
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - David O. Topping
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
- National
Centre for Atmospheric Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Carl Percival
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Chen Cai
- The
Institute of Chemical Physics, Key Laboratory of Cluster Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
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36
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Price HC, Mattsson J, Murray BJ. Sucrose diffusion in aqueous solution. Phys Chem Chem Phys 2016; 18:19207-16. [PMID: 27364512 PMCID: PMC5044753 DOI: 10.1039/c6cp03238a] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/21/2016] [Indexed: 12/02/2022]
Abstract
The diffusion of sugar in aqueous solution is important both in nature and in technological applications, yet measurements of diffusion coefficients at low water content are scarce. We report directly measured sucrose diffusion coefficients in aqueous solution. Our technique utilises a Raman isotope tracer method to monitor the diffusion of non-deuterated and deuterated sucrose across a boundary between the two aqueous solutions. At a water activity of 0.4 (equivalent to 90 wt% sucrose) at room temperature, the diffusion coefficient of sucrose was determined to be approximately four orders of magnitude smaller than that of water in the same material. Using literature viscosity data, we show that, although inappropriate for the prediction of water diffusion, the Stokes-Einstein equation works well for predicting sucrose diffusion under the conditions studied. As well as providing information of importance to the fundamental understanding of diffusion in binary solutions, these data have technological, pharmaceutical and medical implications, for example in cryopreservation. Moreover, in the atmosphere, slow organic diffusion may have important implications for aerosol growth, chemistry and evaporation, where processes may be limited by the inability of a molecule to diffuse between the bulk and the surface of a particle.
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Affiliation(s)
- Hannah C. Price
- School of Earth and Environment , University of Leeds , Leeds , UK .
| | - Johan Mattsson
- School of Physics and Astronomy , University of Leeds , Leeds , UK .
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37
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Steimer SS, Berkemeier T, Gilgen A, Krieger UK, Peter T, Shiraiwa M, Ammann M. Shikimic acid ozonolysis kinetics of the transition from liquid aqueous solution to highly viscous glass. Phys Chem Chem Phys 2016; 17:31101-9. [PMID: 26536455 DOI: 10.1039/c5cp04544d] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ageing of particulate organic matter affects the composition and properties of atmospheric aerosol particles. Driven by temperature and humidity, the organic fraction can vary its physical state between liquid and amorphous solid, or rarely even crystalline. These transitions can influence the reaction kinetics due to limitations of mass transport in such (semi-) solid states, which in turn may influence the chemical ageing of particles containing such compounds. We have used coated wall flow tube experiments to investigate the reaction kinetics of the ozonolysis of shikimic acid, which serves as a proxy for oxygenated, water-soluble organic matter and can form a glass at room temperature. Particular attention was paid to how the presence of water influences the reaction, since it acts a plasticiser and thereby induces changes in the physical state. We analysed the results by means of a traditional resistor model, which assumes steady-state conditions. The ozonolysis rate of shikimic acid is strongly increased in the presence of water, a fact we attribute to the increased transport of O3 and shikimic acid through the condensed phase at lower viscosities. The analysis using the resistor model suggests that the system undergoes both surface and bulk reaction. The second-order rate coefficient of the bulk reaction is 3.7 (+1.5/-3.2) × 10(3) L mol(-1) s(-1). At low humidity and long timescales, the resistor model fails to describe the measurements appropriately. The persistent O3 uptake at very low humidity suggests contribution of a self-reaction of O3 on the surface.
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Affiliation(s)
- Sarah S Steimer
- Paul Scherrer Institute, Laboratory of Radio- and Environmental Chemistry, 5232 Villigen PSI, Switzerland. and ETH Zurich, Institute for Atmospheric and Climate Science, 8092 Zurich, Switzerland
| | - Thomas Berkemeier
- Max Planck Institute for Chemistry, Multiphase Chemistry Department, 55128 Mainz, Germany
| | - Anina Gilgen
- ETH Zurich, Institute for Atmospheric and Climate Science, 8092 Zurich, Switzerland
| | - Ulrich K Krieger
- ETH Zurich, Institute for Atmospheric and Climate Science, 8092 Zurich, Switzerland
| | - Thomas Peter
- ETH Zurich, Institute for Atmospheric and Climate Science, 8092 Zurich, Switzerland
| | - Manabu Shiraiwa
- Max Planck Institute for Chemistry, Multiphase Chemistry Department, 55128 Mainz, Germany
| | - Markus Ammann
- Paul Scherrer Institute, Laboratory of Radio- and Environmental Chemistry, 5232 Villigen PSI, Switzerland.
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38
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Marshall FH, Miles REH, Song YC, Ohm PB, Power RM, Reid JP, Dutcher CS. Diffusion and reactivity in ultraviscous aerosol and the correlation with particle viscosity. Chem Sci 2016; 7:1298-1308. [PMID: 29910887 PMCID: PMC5975831 DOI: 10.1039/c5sc03223g] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/07/2015] [Indexed: 11/21/2022] Open
Abstract
The slow transport of water, organic species and oxidants in viscous aerosol can lead to aerosol existing in transient states that are not solely governed by thermodynamic principles but by the kinetics of gas-particle partitioning. The relationship between molecular diffusion constants and particle viscosity (for example, as reflected in the Stokes-Einstein equation) is frequently considered to provide an approximate guide to relate the kinetics of aerosol transformation with a material property of the aerosol. We report direct studies of both molecular diffusion and viscosity in the aerosol phase for the ternary system water/maleic acid/sucrose, considering the relationship between the hygroscopic response associated with the change in water partitioning, the volatilisation of maleic acid, the ozonolysis kinetics of maleic acid and the particle viscosity. Although water clearly acts as a plasticiser, the addition of minor fractions of other organic moieties can similarly lead to significant changes in the viscosity from that expected for the dominant component forming the organic matrix (sucrose). Here we highlight that the Stokes-Einstein relationship between the diffusion constant of water and the viscosity of the particle may be more than an order of magnitude in error, even at viscosities as low as 1 Pa s. We show that the thermodynamic relationships of hygroscopic response that underpin such kinetic determinations must be accurately known to retrieve accurate values for diffusion constants; such data are often not available. Further, we show that scaling of the diffusion constants of organic molecules of similar size to those forming the matrix with particle viscosity may be well represented by the Stokes-Einstein equation, suppressing the apparent volatility of semi-volatile components. Finally, the variation in uptake coefficients and diffusion constants for oxidants and small weakly interacting molecules may be much less dependent on viscosity than the diffusion constants of more strongly interacting molecules such as water.
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Affiliation(s)
| | - Rachael E H Miles
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - Young-Chul Song
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - Peter B Ohm
- Department of Mechanical Engineering , University of Minnesota , 111 Church Street SE , Minneapolis , MN 55455 , USA
| | - Rory M Power
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
- Max Planck Institute of Molecular Cell Biology and Genetics , Dresden , 01307 , Germany
| | - Jonathan P Reid
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - Cari S Dutcher
- Department of Mechanical Engineering , University of Minnesota , 111 Church Street SE , Minneapolis , MN 55455 , USA
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39
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Davies JF, Wilson KR. Raman Spectroscopy of Isotopic Water Diffusion in Ultraviscous, Glassy, and Gel States in Aerosol by Use of Optical Tweezers. Anal Chem 2016; 88:2361-6. [DOI: 10.1021/acs.analchem.5b04315] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- James F. Davies
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94611, United States
| | - Kevin R. Wilson
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94611, United States
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40
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Berkemeier T, Steimer SS, Krieger UK, Peter T, Pöschl U, Ammann M, Shiraiwa M. Ozone uptake on glassy, semi-solid and liquid organic matter and the role of reactive oxygen intermediates in atmospheric aerosol chemistry. Phys Chem Chem Phys 2016; 18:12662-74. [DOI: 10.1039/c6cp00634e] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Humidity-induced phase transition and formation of reactive oxygen intermediates are important processes in the heterogeneous ozonolysis of unsaturated organic compounds in the atmosphere.
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Affiliation(s)
- Thomas Berkemeier
- Max Planck Institute for Chemistry
- Multiphase Chemistry Department
- 55128 Mainz
- Germany
| | - Sarah S. Steimer
- Paul Scherrer Institute
- Laboratory of Environmental Chemistry
- 5232 Villigen PSI
- Switzerland
- ETH Zurich
| | - Ulrich K. Krieger
- ETH Zurich
- Institute for Atmospheric and Climate Science
- 8092 Zurich
- Switzerland
| | - Thomas Peter
- ETH Zurich
- Institute for Atmospheric and Climate Science
- 8092 Zurich
- Switzerland
| | - Ulrich Pöschl
- Max Planck Institute for Chemistry
- Multiphase Chemistry Department
- 55128 Mainz
- Germany
| | - Markus Ammann
- Paul Scherrer Institute
- Laboratory of Environmental Chemistry
- 5232 Villigen PSI
- Switzerland
| | - Manabu Shiraiwa
- Max Planck Institute for Chemistry
- Multiphase Chemistry Department
- 55128 Mainz
- Germany
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41
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Athanasiadis A, Fitzgerald C, Davidson NM, Giorio C, Botchway SW, Ward AD, Kalberer M, Pope FD, Kuimova MK. Dynamic viscosity mapping of the oxidation of squalene aerosol particles. Phys Chem Chem Phys 2016; 18:30385-30393. [DOI: 10.1039/c6cp05674a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The microscopic viscosity of squalene-based organic aerosol undergoing atmospherically relevant oxidation is investigated.
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Affiliation(s)
| | | | - Nicholas M. Davidson
- School of Geography
- Earth and Environmental Science
- University of Birmingham
- Edgbaston
- UK
| | - Chiara Giorio
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Stanley W. Botchway
- Central Laser Facility
- Research Complex at Harwell
- Rutherford Appleton Laboratory
- Oxon OX11 0QX
- UK
| | - Andrew D. Ward
- Central Laser Facility
- Research Complex at Harwell
- Rutherford Appleton Laboratory
- Oxon OX11 0QX
- UK
| | | | - Francis D. Pope
- School of Geography
- Earth and Environmental Science
- University of Birmingham
- Edgbaston
- UK
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42
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Hinks ML, Brady MV, Lignell H, Song M, Grayson JW, Bertram AK, Lin P, Laskin A, Laskin J, Nizkorodov SA. Effect of viscosity on photodegradation rates in complex secondary organic aerosol materials. Phys Chem Chem Phys 2016; 18:8785-93. [DOI: 10.1039/c5cp05226b] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This work explores the effect of environmental conditions on the photodegradation rates of atmospherically relevant, photolabile, organic molecules embedded in a film of viscous secondary organic material (SOM).
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Affiliation(s)
| | | | - Hanna Lignell
- Department of Chemistry
- University of California
- Irvine
- USA
| | - Mijung Song
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - James W. Grayson
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - Allan K. Bertram
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - Peng Lin
- Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Alexander Laskin
- Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Julia Laskin
- Physical Sciences Division
- Pacific Northwest National Laboratory
- Richland
- USA
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43
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Li YJ, Liu P, Gong Z, Wang Y, Bateman AP, Bergoend C, Bertram AK, Martin ST. Chemical Reactivity and Liquid/Nonliquid States of Secondary Organic Material. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:13264-74. [PMID: 26465059 DOI: 10.1021/acs.est.5b03392] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The reactivity of secondary organic material (SOM) of variable viscosity, ranging from nonliquid to liquid physical states, was studied. The SOM, produced in aerosol form from terpenoid and aromatic precursor species, was reacted with ammonia at variable relative humidity (RH). The ammonium-to-organic mass ratio (MNH4+/MOrg) increased monotonically from <5% RH to a limiting value at a threshold RH, implicating a transition from particle reactivity limited by diffusion at low RH to one limited by other factors at higher RH. For the studied size distributions and reaction times, the transition corresponded to a diffusivity above 10-17.5 ± 0.5 m2 s-1. The threshold RH values for the transition were <5% RH for isoprene-derived SOM, 35-45% RH for SOM derived from α-pinene, toluene, m-xylene, and 1,3,5-trimethylbenzene, and >90% for β-caryophyllene-derived SOM. The transition RH for reactivity differed in all cases from the transition RH of a nonliquid to a liquid state. For instance, for α-pinene-derived SOM the transition for chemical reactivity of 35-45% RH can be compared to the nonliquid to liquid transition of 65-90% RH. These differences imply that chemical transport models of atmospheric chemistry should not use the SOM liquid to nonliquid phase transition as one-to-one surrogates of SOM reactivity.
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Affiliation(s)
- Yong Jie Li
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau , Avenida da Universidade, Taipa, Macau, China
| | - Pengfei Liu
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Zhaoheng Gong
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Yan Wang
- Department of Environmental Health, Harvard T.H. Chan School of Public Health , Boston, Massachusetts 02115, United States
| | - Adam P Bateman
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Clara Bergoend
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Energy and Environment, National Institute of Applied Science of Lyon , Villeurbanne 69100, France
| | - Allan K Bertram
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
| | - Scot T Martin
- School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Earth and Planetary Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
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44
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Hosny NA, Fitzgerald C, Vyšniauskas A, Athanasiadis A, Berkemeier T, Uygur N, Pöschl U, Shiraiwa M, Kalberer M, Pope FD, Kuimova MK. Direct imaging of changes in aerosol particle viscosity upon hydration and chemical aging. Chem Sci 2015; 7:1357-1367. [PMID: 29910892 PMCID: PMC5975791 DOI: 10.1039/c5sc02959g] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/07/2015] [Indexed: 12/22/2022] Open
Abstract
We report quantitative, real-time, online observations of microscopic viscosity changes in aerosol particles of atmospherically relevant composition, using fluorescence lifetime imaging (FLIM) of viscosity.
Organic aerosol particles (OA) play major roles in atmospheric chemistry, climate, and public health. Aerosol particle viscosity is highly important since it can determine the ability of chemical species such as oxidants, organics or water to diffuse into the particle bulk. Recent measurements indicate that OA may be present in highly viscous states, however, diffusion rates of small molecules such as water are not limited by these high viscosities. Direct observational evidence of kinetic barriers caused by high viscosity and low diffusivity in aerosol particles were not available until recently; and techniques that are able to dynamically quantify and track viscosity changes during atmospherically relevant processes are still unavailable for atmospheric aerosols. Here we report quantitative, real-time, online observations of microscopic viscosity changes in aerosol particles of atmospherically relevant composition, using fluorescence lifetime imaging (FLIM) of viscosity. We show that microviscosity in ozonated oleic acid droplets and secondary organic aerosol (SOA) particles formed by ozonolysis of myrcene increases substantially with decreasing humidity and atmospheric oxidative aging processes. Furthermore, we found unexpected heterogeneities of microviscosity inside individual aerosol particles. The results of this study enhance our understanding of organic aerosol processes on microscopic scales and may have important implications for the modeling of atmospheric aerosol growth, composition and interactions with trace gases and clouds.
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Affiliation(s)
- N A Hosny
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - C Fitzgerald
- Department of Chemistry , University of Cambridge , Cambridge , CB2 1EW , UK .
| | - A Vyšniauskas
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - A Athanasiadis
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - T Berkemeier
- Multiphase Chemistry Department , Max Planck Institute for Chemistry , Hahn-Meitner Weg 1 , 55128 , Mainz , Germany
| | - N Uygur
- Multiphase Chemistry Department , Max Planck Institute for Chemistry , Hahn-Meitner Weg 1 , 55128 , Mainz , Germany
| | - U Pöschl
- Multiphase Chemistry Department , Max Planck Institute for Chemistry , Hahn-Meitner Weg 1 , 55128 , Mainz , Germany
| | - M Shiraiwa
- Multiphase Chemistry Department , Max Planck Institute for Chemistry , Hahn-Meitner Weg 1 , 55128 , Mainz , Germany
| | - M Kalberer
- Department of Chemistry , University of Cambridge , Cambridge , CB2 1EW , UK .
| | - F D Pope
- School of Geography , Earth and Environmental Science , University of Birmingham , Edgbaston , B15 2TT , UK .
| | - M K Kuimova
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
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45
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Davies JF, Wilson KR. Nanoscale interfacial gradients formed by the reactive uptake of OH radicals onto viscous aerosol surfaces. Chem Sci 2015; 6:7020-7027. [PMID: 29861940 PMCID: PMC5947524 DOI: 10.1039/c5sc02326b] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/05/2015] [Indexed: 01/25/2023] Open
Abstract
A key but poorly understood chemical process is how gas phase uptake is governed by the relative mobility of molecules at an interface of an atmospheric aerosol. Citric acid (CA), a model system for oxygenated organic aerosol, is used to examine how changes in viscosity, due to changing water content, govern the reactive uptake of gas phase hydroxyl radicals (OH). By comparing the reaction kinetics measured when probing the outer aerosol surface layers with measurements of the bulk particle composition, the effective OH reaction probability is observed to be a complex and non-linear function of the relative humidity (RH). At RH < 50%, the reactive decay of CA is controlled by the viscosity of the particle, where the depletion of CA and the formation of reaction products occurs over a narrow region near the aerosol interface, on the order of 8 nm at 20% RH. At RH = 50% the reaction zone increases to the particle dimensions (i.e. ∼50 nm) and at RH > 50%, the aerosol becomes aqueous and well-mixed on the timescale of the heterogeneous reaction. These results imply that in the atmosphere, the formation and dissipation of interfacial chemical gradients could be significant in viscous and semisolid aerosol and play important roles altering gas-particle partitioning and aging mechanisms (i.e. bulk vs. interface).
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Affiliation(s)
- James F Davies
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , 1 Cyclotron Road , Berkeley , CA 94720 , USA .
| | - Kevin R Wilson
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , 1 Cyclotron Road , Berkeley , CA 94720 , USA .
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46
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Cai C, Tan S, Chen H, Ma J, Wang Y, Reid JP, Zhang Y. Slow water transport in MgSO4 aerosol droplets at gel-forming relative humidities. Phys Chem Chem Phys 2015; 17:29753-63. [DOI: 10.1039/c5cp05181a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The effect of gel formation on water transport in MgSO4 aerosol droplets is investigated by deriving apparent diffusion coefficients of water.
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Affiliation(s)
- Chen Cai
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | - Seehua Tan
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | - Hongnan Chen
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | - Jiabi Ma
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | - Yang Wang
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
| | | | - Yunhong Zhang
- The Institute of Chemical Physics
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- People's Republic of China
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