1
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Ng SIM, Chan MN. Beyond the formation: unveiling the atmospheric transformation of organosulfates via heterogeneous OH oxidation. Chem Commun (Camb) 2023; 59:13919-13938. [PMID: 37933441 DOI: 10.1039/d3cc03700b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Organosulfates (OSs), characterized with a sulfate ester group (R-OSO3-), are abundant constituents in secondary organic aerosols. Recent laboratory-based investigations have revealed that OSs can undergo efficient chemical transformation through heterogeneous oxidation by hydroxyl radicals (˙OH, interchangeably termed as OH in this article), which freshly derives functionalized and fragmented OSs. The reaction not only contributes to the presence of structurally transformed OSs in the atmosphere of which sources were unidentified, but it also leads to the formation of inorganic sulfates (e.g., SO42-) with profound implication on the form of aerosol sulfur. In this article, we review the current state of knowledge regarding the heterogeneous OH oxidation of OSs based on state-of-the-art designs of experiments, computational approaches, and chemical analytical techniques. Here, we discuss the formation potential of new OSs and SO42-, in light of the influence of diverse OS structures on the relative importance of different reaction pathways. We propose future research directions to advance our mechanistic understanding of these reactions, taking into account aerosol matrix effects, interactions with other atmospheric pollutants, and the incorporation of experimental findings into atmospheric chemical transport models.
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Affiliation(s)
- Sze In Madeleine Ng
- Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, China.
| | - Man Nin Chan
- Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, China.
- The Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong, China
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2
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Kaur Kohli R, Salas S, Shokoor B, Price CL, Davies JF. Chemically Resolved Evaporation Dynamics of Dicarboxylic Acid Mixtures in Solid Particles. Anal Chem 2023. [PMID: 37490783 DOI: 10.1021/acs.analchem.3c02475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
The evaporation rate and corresponding vapor pressure of dicarboxylic acids have been the subject of numerous scientific studies over the years, with reported values spanning several orders of magnitude. Recent work has identified the importance of considering the phase state of the material during evaporation, likely accounting for some of the variability in measured vapor pressures. In the homologous series of dicarboxylic acids, the phase state under dry conditions may be crystalline or amorphous, with particles of odd-carbon-numbered acids exhibiting tendencies to remain amorphous and spherical. Although measurements of vapor pressures for pure components make up most of the available literature data, for many applications, these compounds are not present in isolation. Additionally, many systems containing a semi-volatile material exist in a solid state, especially under dry and low relative humidity conditions. In this work, we explore the evaporation of compounds present in mixed solid-state particles. Specifically, we use single particle levitation coupled with mass spectrometry to measure the evolving composition of solid particles containing mixtures of glutaric acid and succinic acid, glutaric acid and adipic acid, and malonic acid and succinic acid. Under dry conditions, these systems exhibit non-spherical geometries consistent with crystallization of one or both components into an organic crystal. Our measurements allow the evaporation of each component in the mixture to be characterized independently and effective vapor pressures of the pure components to be inferred. The resulting vapor pressures are compared against pure component vapor pressures. We demonstrate that these mixtures exhibit thermodynamic ideality but can be influenced by limited diffusion in the solid phase. These are the first results in the literature that explore the thermodynamic and kinetic factors that control the evaporative evolution of mixed solid-state particles.
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Affiliation(s)
- Ravleen Kaur Kohli
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Stephanie Salas
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Bilal Shokoor
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - Chelsea L Price
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
| | - James F Davies
- Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
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3
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Li J, Chang Y. Ozone oxidation of cysteine in optically trapped aqueous micro‐droplets. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202300050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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4
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Kaluarachchi C, Or VW, Lan Y, Hasenecz ES, Kim D, Madawala CK, Dorcé GP, Mayer KJ, Sauer JS, Lee C, Cappa CD, Bertram TH, Stone EA, Prather KA, Grassian VH, Tivanski AV. Effects of Atmospheric Aging Processes on Nascent Sea Spray Aerosol Physicochemical Properties. ACS EARTH & SPACE CHEMISTRY 2022; 6:2732-2744. [PMID: 36425339 PMCID: PMC9677592 DOI: 10.1021/acsearthspacechem.2c00258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/30/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
The effects of atmospheric aging on single-particle nascent sea spray aerosol (nSSA) physicochemical properties, such as morphology, composition, phase state, and water uptake, are important to understanding their impacts on the Earth's climate. The present study investigates these properties by focusing on the aged SSA (size range of 0.1-0.6 μm) and comparing with a similar size range nSSA, both generated at a peak of a phytoplankton bloom during a mesocosm study. The aged SSAs were generated by exposing nSSA to OH radicals with exposures equivalent to 4-5 days of atmospheric aging. Complementary filter-based thermal optical analysis, atomic force microscopy (AFM), and AFM photothermal infrared spectroscopy were utilized. Both nSSA and aged SSA showed an increase in the organic mass fraction with decreasing particle sizes. In addition, aging results in a further increase of the organic mass fraction, which can be attributed to new particle formation and oxidation of volatile organic compounds followed by condensation on pre-existing particles. The results are consistent with single-particle measurements that showed a relative increase in the abundance of aged SSA core-shells with significantly higher organic coating thickness, relative to nSSA. Increased hygroscopicity was observed for aged SSA core-shells, which had more oxygenated organic species. Rounded nSSA and aged SSA had similar hygroscopicity and no apparent changes in the composition. The observed changes in aged SSA physicochemical properties showed a significant size-dependence and particle-to-particle variability. Overall, results showed that the atmospheric aging can significantly influence the nSSA physicochemical properties, thus altering the SSA effects on the climate.
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Affiliation(s)
| | - Victor W. Or
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - Yiling Lan
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Elias S. Hasenecz
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Deborah Kim
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - Chamika K. Madawala
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Glorianne P. Dorcé
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Kathryn J. Mayer
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - Jonathan S. Sauer
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
| | - Christopher Lee
- Scripps
Institution of Oceanography, University
of California, San Diego, La Jolla, California 92093, United States
| | - Christopher D. Cappa
- Department
of Civil and Environmental Engineering, University of California, Davis, California 95616, United States
| | - Timothy H. Bertram
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Elizabeth A. Stone
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Kimberly A. Prather
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
- Scripps
Institution of Oceanography, University
of California, San Diego, La Jolla, California 92093, United States
| | - Vicki H. Grassian
- Department
of Chemistry and Biochemistry, University
of California, San Diego, La Jolla, California 92093, United States
- Scripps
Institution of Oceanography, University
of California, San Diego, La Jolla, California 92093, United States
| | - Alexei V. Tivanski
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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5
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Willis MD, Wilson KR. Coupled Interfacial and Bulk Kinetics Govern the Timescales of Multiphase Ozonolysis Reactions. J Phys Chem A 2022; 126:4991-5010. [PMID: 35863113 DOI: 10.1021/acs.jpca.2c03059] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chemical transformations in aerosols impact the lifetime of particle phase species, the fate of atmospheric pollutants, and both climate- and health-relevant aerosol properties. Timescales for multiphase reactions of ozone in atmospheric aqueous phases are governed by coupled kinetic processes between the gas phase, the particle interface, and its bulk, which respond dynamically to reactive consumption of O3. However, models of atmospheric aerosol reactivity often do not account for the coupled nature of multiphase processes. To examine these dynamics, we use new and prior experimental observations of aqueous droplet reaction kinetics, including three systems with a range of surface affinities and ozonolysis rate coefficients (trans-aconitic acid (C6H6O6), maleic acid (C4H4O4), and sodium nitrite (NaNO2)). Using literature rate coefficients and thermodynamic properties, we constrain a simple two-compartment stochastic kinetic model which resolves the interface from the particle bulk and represents O3 partitioning, diffusion, and reaction as a coupled kinetic system. Our kinetic model accurately predicts decay kinetics across all three systems, demonstrating that both the thermodynamic properties of O3 and the coupled kinetic and diffusion processes are key to making accurate predictions. An enhanced concentration of adsorbed O3, compared to gas and bulk phases is rapidly maintained and remains constant even as O3 is consumed by reaction. Multiphase systems dynamically seek to achieve equilibrium in response to reactive O3 loss, but this is hampered at solute concentrations relevant to aqueous aerosol by the rate of O3 arrival in the bulk by diffusion. As a result, bulk-phase O3 becomes depleted from its Henry's law solubility. This bulk-phase O3 depletion limits reaction timescales for relatively slow-reacting organic solutes with low interfacial affinity (i.e., trans-aconitic and maleic acids, with krxn ≈ 103-104 M-1 s-1), which is in contrast to fast-reacting solutes with higher surface affinity (i.e., nitrite, with krxn ≈ 105 M-1 s-1) where surface reactions strongly impact the observed decay kinetics.
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Affiliation(s)
- Megan D Willis
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Kevin R Wilson
- Chemical Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
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6
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Tong YK, Liu Y, Meng X, Wang J, Zhao D, Wu Z, Ye A. The relative humidity-dependent viscosity of single quasi aerosol particles and possible implications for atmospheric aerosol chemistry. Phys Chem Chem Phys 2022; 24:10514-10523. [PMID: 35441631 DOI: 10.1039/d2cp00740a] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Viscosity is a fundamental physicochemical property of aerosol particles that influences chemical evolution, mass transfer rates, particle formation, etc. and also changes with ambient relative humidity (RH). However, the viscosity of real individual aerosol particles still remains less understood. Here, we developed a novel optical system based on dual optical tweezers to measure the viscosity of single suspending aerosol droplets under different RH conditions. In our experiment, a pair of quasi atmospheric aerosol droplets composed of organic and inorganic chemical substances were trapped and levitated by dual laser beams, respectively, and then collided and coalesced. The backscattering light signals and bright-field images of the dynamic coalescence process were recorded to infer the morphological relaxation time and the diameter of the composited droplet. Then, the viscosity of the droplet was calculated based on these measured values. The ambient RH of the aerosol droplets was controlled by varying the relative flow rates of dry and humidified nitrogen gas in a self-developed aerosol chamber. The viscosities of single aqueous droplets nebulized with solutes of sucrose, various sulfates and nitrates, and organic/inorganic mixtures were measured over the atmospheric RH range. Besides, the viscosities of the proxies of actual ambient aerosols in Beijing were investigated, which reasonably interpreted the aerosol chemistry transforming from sulfate dominating to nitrate dominating at the PM10 (particulate matter with an aerodynamic diameter of less than 10 μm) level in the last decade in Beijing. Furthermore, the hygroscopicity of droplets with a solute of organic/inorganic mixtures was researched to obtain a deep insight into the relationship between the viscosity and mass transfer process. Hence, we provide a robust approach for investigating the viscosity and hygroscopicity of the actual individual liquid PM10 aerosols.
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Affiliation(s)
- Yu-Kai Tong
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
| | - Yaoyao Liu
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
| | - Xiangxinyue Meng
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Jie Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
| | - Dongping Zhao
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
| | - Zhijun Wu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Anpei Ye
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
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7
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Dalton AB, Nizkorodov SA. Photochemical Degradation of 4-Nitrocatechol and 2,4-Dinitrophenol in a Sugar-Glass Secondary Organic Aerosol Surrogate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14586-14594. [PMID: 34669384 DOI: 10.1021/acs.est.1c04975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The roles that chemical environment and viscosity play in the photochemical fate of molecules trapped in atmospheric particles are poorly understood. The goal of this work was to characterize the photolysis of 4-nitrocatechol (4NC) and 2,4-dinitrophenol (24DNP) in semisolid isomalt as a new type of surrogate for glassy organic aerosols and compare it to photolysis in liquid water, isopropanol, and octanol. UV/vis spectroscopy was used to monitor the absorbance decay to determine the rates of photochemical loss of 4NC and 24DNP. The quantum yield of 4NC photolysis was found to be smaller in an isomalt glass (2.6 × 10-6) than in liquid isopropanol (1.1 × 10-5). Both 4NC and 24NDP had much lower photolysis rates in water than in organic matrices, suggesting that they would photolyze more efficiently in organic aerosol particles than in cloud or fog droplets. Liquid chromatography in tandem with mass spectrometry was used to examine the photolysis products of 4NC. In isopropanol solution, most products appeared to result from the oxidation of 4NC, in stark contrast to photoreduction and dimerization products that were observed in solid isomalt. Therefore, the photochemical fate of 4NC, and presumably of other nitrophenols, should depend on whether they undergo photodegradation in a liquid or semisolid organic particle.
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Affiliation(s)
- Avery B Dalton
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Sergey A Nizkorodov
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
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8
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Chang YP, Devi Y, Chen CH. Micro-droplet Trapping and Manipulation: Understanding Aerosol Better for a Healthier Environment. Chem Asian J 2021; 16:1644-1660. [PMID: 33999498 DOI: 10.1002/asia.202100516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Indexed: 11/09/2022]
Abstract
Understanding the physicochemical properties and heterogeneous processes of aerosols is key not only to elucidate the impacts of aerosols on the atmosphere and humans but also to exploit their further applications, especially for a healthier environment. Experiments that allow for spatially control of single aerosol particles and investigations on the fundamental properties and heterogeneous chemistry at the single-particle level have flourished during the last few decades, and significant breakthroughs in recent years promise better control and novel applications aimed at resolving key issues in aerosol science. Here we propose graphene oxide (GO) aerosols as prototype aerosols containing polycyclic aromatic hydrocarbons, and GO can behave as two-dimensional surfactants which could modify the interfacial properties of aerosols. We describe the techniques of trapping single particles and furthermore the current status of the optical spectroscopy and chemistry of GO. The current applications of these single-particle trapping techniques are summarized and interesting future applications of GO aerosols are discussed.
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Affiliation(s)
- Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Yanita Devi
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Chun-Hu Chen
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
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9
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Liang Z, Zhang R, Gen M, Chu Y, Chan CK. Nitrate Photolysis in Mixed Sucrose-Nitrate-Sulfate Particles at Different Relative Humidities. J Phys Chem A 2021; 125:3739-3747. [PMID: 33899478 DOI: 10.1021/acs.jpca.1c00669] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atmospheric particles can be viscous. The limitation in diffusion impedes the mass transfer of oxidants from the gas phase to the particle phase and hinders multiphase oxidation processes. On the other hand, nitrate photolysis has been found to be effective in producing oxidants such as OH radicals within the particles. Whether nitrate photolysis can effectively proceed in viscous particles and how it may affect the physicochemical properties of the particle have not been much explored. In this study, we investigated particulate nitrate photolysis in mixed sucrose-nitrate-sulfate particles as surrogates of atmospheric viscous particles containing organic and inorganic components as a function of relative humidity (RH) and the molar fraction of sucrose to the total solute (FSU) with an in situ micro-Raman system. Sucrose suppressed nitrate crystallization, and high photolysis rate constants (∼10-5 s-1) were found, irrespective of the RH. For FSU = 0.5 and 0.33 particles under irradiation at 30% RH, we observed morphological changes from droplets to the formation of inclusions and then likely "hollow" semisolid particles, which did not show Raman signal at central locations. Together with the phase states of inorganics indicated by the full width at half-maxima (FWHM), images with bulged surfaces, and size increase of the particles in optical microscopic imaging, we inferred that the hindered diffusion of gaseous products (i.e., NOx, NOy) from nitrate photolysis is a likely reason for the morphological changes. Atmospheric implications of these results are also presented.
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Affiliation(s)
- Zhancong Liang
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong, China
| | - Ruifeng Zhang
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong, China
| | - Masao Gen
- Faculty of Frontier Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yangxi Chu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Chak K Chan
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong, China
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10
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Ingram S, Rovelli G, Song YC, Topping D, Dutcher CS, Liu S, Nandy L, Shiraiwa M, Reid JP. Accurate Prediction of Organic Aerosol Evaporation Using Kinetic Multilayer Modeling and the Stokes-Einstein Equation. J Phys Chem A 2021; 125:3444-3456. [PMID: 33861595 DOI: 10.1021/acs.jpca.1c00986] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Organic aerosol can adopt a wide range of viscosities, from liquid to glass, depending on the local humidity. In highly viscous droplets, the evaporation rates of organic components are suppressed to varying degrees, yet water evaporation remains fast. Here, we examine the coevaporation of semivolatile organic compounds (SVOCs), along with their solvating water, from aerosol particles levitated in a humidity-controlled environment. To better replicate the composition of secondary aerosol, nonvolatile organics were also present, creating a three-component diffusion problem. Kinetic modeling reproduced the evaporation accurately when the SVOCs were assumed to obey the Stokes-Einstein relation, and water was not. Crucially, our methodology uses previously collected data to constrain the time-dependent viscosity, as well as water diffusion coefficients, allowing it to be predictive rather than postdictive. Throughout the study, evaporation rates were found to decrease as SVOCs deplete from the particle, suggesting path function type behavior.
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Affiliation(s)
- Stephen Ingram
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Grazia Rovelli
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Young-Chul Song
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - David Topping
- Department of Earth and Environmental Sciences, University of Manchester, Oxford Rd, Manchester M13 9PL, U.K
| | - Cari S Dutcher
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, Minnesota 55455, United States.,Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Shihao Liu
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, Minnesota 55455, United States
| | - Lucy Nandy
- Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, Minnesota 55455, United States
| | - Manabu Shiraiwa
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
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11
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Lv XJ, Chen Z, Ma JB, Zhang YH. Evaporation of mixed citric acid/(NH 4) 2SO 4/H 2O particles: Volatility of organic aerosol by using optical tweezers. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 226:117552. [PMID: 31629977 DOI: 10.1016/j.saa.2019.117552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/26/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
The condensation and evaporation processes of semi-volatile organic compounds (SVOCs) in atmospheric aerosols can induce significant evolutions of their chemical and physical properties. Hence, for interpreting and predicting composition changes of atmospheric aerosols, it is indispensable to provide insight into the partitioning behaviors of SVOCs between condensed and gas phases. In this research, optical tweezers coupled with cavity-enhanced Raman spectroscopy were employed to observe the volatility of internally mixed citric acid (CA)/(NH4)2SO4 (AS) particles, and the effect of AS on the gas/particle partitioning behaviors of atmospheric organic acids was investigated. The radii and refractive indexes of the levitated droplets were determined in real time from the wavelength positions of simulated Raman spectra and the effective vapor pressures of CA at different relative humidities (RHs) were obtained according to Maxwell equation. For the CA/AS particle with organic to inorganic mole ratio (OIR) of 1:1, the effective vapor pressure of CA decreased with the decreasing of RH. When the RH decreased from 67% to 8.2%, the effective vapor pressure of CA decreased from (1.35±0.508)×10-4Pa to (3.0±1.0)×10-6Pa. Meanwhile, the CA/AS particles with OIR of 3:1, 1:3 were also studied, and the results show the same phenomenon compared to the particles with OIR of 1:1. When under constant RHs, the effective vapor pressures of CA decreased with the increasing of AS contents, suggesting that the presence of AS suppressed the partitioning of CA to aqueous particles. In addition, the mass transfer processes of water in CA and CA/AS/H2O systems were further studied. The characteristic time ratio between the droplet radius and RH was used to describe the water mass transfer difference dependent on RH. Compared to the characteristic time ratio of pure CA, the characteristic time ratio of CA/AS particles apparently increased. For CA/AS particles under the same RH steps, the characteristic time ratio increased with the AS content increase. According to the differential isotherm, the diffusion coefficients of citric acid and citric acid/ammonium sulfate at low RHs (RH ≈7%-1%, RH≈1%-7%) were calculated respectively. Generally, the key aspect of the current work was to deeply explore the relationship between the evaporation rates of SVOCs and water transport process.
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Affiliation(s)
- Xi-Juan Lv
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Zhe Chen
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Jia-Bi Ma
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
| | - Yun-Hong Zhang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
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12
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Zhou Z, Zhou S, Abbatt JPD. Kinetics and Condensed-Phase Products in Multiphase Ozonolysis of an Unsaturated Triglyceride. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12467-12475. [PMID: 31600435 DOI: 10.1021/acs.est.9b04460] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ozone is an important oxidant in the environment. To study the nature of multiphase ozonolysis, an unsaturated triglyceride, triolein, of the type present in skin oil, biological membranes, and most cooking oils was oxidized by gas-phase ozone on a surface. A high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) method was developed for analyzing triolein and its oxidized products. Upon exposure to ozone, the decay of thin coatings of triolein was observed, accompanied by the formation of functionalized condensed-phase products including secondary ozonides (SOZ), acids, and aldehydes. By studying the reaction kinetics as a function of average coating thickness and ozone mixing ratio, we determined that the reactive uptake coefficient (γ) is on the order of 10-6 to 10-5. It is also concluded that the reaction occurs in the bulk without a major interfacial component, and the reacto-diffusive depth of ozone in the triolein coating is estimated to be between 8 and 40 nm. The specific nature of the reaction products is affected by the reactions of the Criegee intermediate formed during ozonolysis. In particular, although an increase in the relative humidity to 50% from dry conditions has no effect on the kinetics of triolein decay, the yield of SOZs is significantly depressed, indicating reactions of the Criegee intermediates to form hydroperoxides. Once formed, the SOZ products are thermally stable over periods of at least 48 h at room temperature but decomposition was observed under simulated outdoor sunlight, likely forming organic acids. From an environmental perspective, this chemistry indicates that SOZs and other oxygenates will form via ozonolysis of oily indoor surfaces and skin oil.
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Affiliation(s)
- Zilin Zhou
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , ON M5S 3H6 , Canada
| | - Shouming Zhou
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , ON M5S 3H6 , Canada
| | - Jonathan P D Abbatt
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , ON M5S 3H6 , Canada
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13
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Jacobs MI, Xu B, Kostko O, Wiegel AA, Houle FA, Ahmed M, Wilson KR. Using Nanoparticle X-ray Spectroscopy to Probe the Formation of Reactive Chemical Gradients in Diffusion-Limited Aerosols. J Phys Chem A 2019; 123:6034-6044. [DOI: 10.1021/acs.jpca.9b04507] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Michael I. Jacobs
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Bo Xu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Oleg Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron A. Wiegel
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Frances A. Houle
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Kevin R. Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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