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Prisle NL. Surfaces of Atmospheric Droplet Models Probed with Synchrotron XPS on a Liquid Microjet. Acc Chem Res 2024; 57:177-187. [PMID: 38156821 PMCID: PMC10795169 DOI: 10.1021/acs.accounts.3c00201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Indexed: 01/03/2024]
Abstract
ConspectusThe atmosphere is a key part of the earth system comprising myriad chemical species in all basic forms of matter. Ubiquitous nano- and microscopic aerosol particles and cloud droplets suspended in the air play crucial roles in earth's climate and the formation of air pollution. Surfaces are a prominent part of aerosols and droplets, due to the high surface area to bulk volume ratios, but very little is known about their specific properties. Many atmospheric compounds are surface-active, leading to enhanced surface concentrations in aqueous solutions. Their distribution between the surface and bulk may determine heterogeneous chemistry and many other properties of aerosol and cloud droplets, but has not been directly observed.We used X-ray photoelectron spectroscopy (XPS) to obtain direct molecular-level information on the surface composition and structure of aqueous solutions of surface-active organics as model systems for atmospheric aerosol and cloud droplets. XPS is a vacuum-based technique enabled for volatile aqueous organic samples by the application of a high-speed liquid microjet. In combination with brilliant synchrotron X-rays, the chemical specificity of XPS allows distinction between elements in different chemical states and positions within molecular structures. We used core-level C 1s and N 1s signals to identify the alkyl and hydrophilic groups of atmospheric carboxylic acids, alkyl-amines, and their conjugate acids and bases. From this, we infer changes in the orientation of surface-adsorbed species and quantify their relative abundances in the surface. XPS-derived surface enrichments of the organics follow trends expected from their surface activities and we observed a preferential orientation at the surface with the hydrophobic alkyl chains pointing increasingly outward from the solution at higher concentrations. This provides a first direct experimental observation of well-established concepts of surface adsorption and confirms the soundness of the method.We mapped relative abundances of conjugate acid-base pairs in the aqueous solution surfaces from the respective intensities of distinctive XPS signals. For each pair, the protonation equilibrium was significantly shifted toward the neutral form in the surface, compared to the bulk solution, across the full pH range. This represents an apparent shift of the pKa in the surface, which may be toward either higher or lower pH, depending on whether the acid or base form of the pair is the neutral species. The surface shifts are broadly consistent with the relative differences in surface enrichment of the individual acid and base conjugates in binary aqueous solutions, with additional contributions from nonideal interactions in the surface. In aqueous mixtures of surface-active carboxylate anions with ammonium salts at near-neutral pH, we found that the conjugate carboxylic acids were further strongly enhanced. This occurs as the coadsorption of weakly basic carboxylate anions and weakly acidic ammonium cations forms ion-pair surface layers with strongly enhanced local abundances, increasing the probability of net proton transfer according to Le Chatelier's principle. The effect is stronger when the evaporation of ammonia from the surface further contributes to irreversibly perturb the protonation equilibrium, leaving a surplus of carboxylic acid. These surface-specific effects may profoundly influence atmospheric chemistry mediated by aqueous aerosols and cloud droplets but are currently not taken into account in atmospheric models.
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Affiliation(s)
- Nønne L. Prisle
- Center for Atmospheric Research, University of Oulu, P.O. Box 4500, Oulu 90014, Finland
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2
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Hyttinen N, Pihlajamäki A, Häkkinen H. Machine Learning for Predicting Chemical Potentials of Multifunctional Organic Compounds in Atmospherically Relevant Solutions. J Phys Chem Lett 2022; 13:9928-9933. [PMID: 36259771 PMCID: PMC9619930 DOI: 10.1021/acs.jpclett.2c02612] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
We have trained the Extreme Minimum Learning Machine (EMLM) machine learning model to predict chemical potentials of individual conformers of multifunctional organic compounds containing carbon, hydrogen, and oxygen. The model is able to predict chemical potentials of molecules that are in the size range of the training data with a root-mean-square error (RMSE) of 0.5 kcal/mol. There is also a linear correlation between calculated and predicted chemical potentials of molecules that are larger than those included in the training set. Finding the lowest chemical potential conformers is useful in condensed phase thermodynamic property calculations, in order to reduce the number of computationally demanding density functional theory calculations.
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Affiliation(s)
- Noora Hyttinen
- Department
of Chemistry, Nanoscience Center, University
of Jyväskylä, FI-40014 Jyväskylä, Finland
| | - Antti Pihlajamäki
- Department
of Physics, Nanoscience Center, University
of Jyväskylä, FI-40014 Jyväskylä, Finland
| | - Hannu Häkkinen
- Department
of Chemistry, Nanoscience Center, University
of Jyväskylä, FI-40014 Jyväskylä, Finland
- Department
of Physics, Nanoscience Center, University
of Jyväskylä, FI-40014 Jyväskylä, Finland
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3
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Chen S, Artiglia L, Orlando F, Edebeli J, Kong X, Yang H, Boucly A, Corral Arroyo P, Prisle N, Ammann M. Impact of Tetrabutylammonium on the Oxidation of Bromide by Ozone. ACS EARTH & SPACE CHEMISTRY 2021; 5:3008-3021. [PMID: 34825122 PMCID: PMC8607506 DOI: 10.1021/acsearthspacechem.1c00233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 10/01/2021] [Accepted: 10/09/2021] [Indexed: 06/13/2023]
Abstract
The reaction of ozone with sea-salt derived bromide is relevant for marine boundary layer atmospheric chemistry. The oxidation of bromide by ozone is enhanced at aqueous interfaces. Ocean surface water and sea spray aerosol are enriched in organic compounds, which may also have a significant effect on this reaction at the interface. Here, we assess the surface propensity of cationic tetrabutylammonium at the aqueous liquid-vapor interface by liquid microjet X-ray photoelectron spectroscopy (XPS) and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The results clearly indicate that the positively charged nitrogen group in tetrabutylammonium (TBA), along with its surface activity, leads to an enhanced interfacial concentration of both bromide and the bromide ozonide reaction intermediate. In parallel, off-line kinetic experiments for the same system demonstrate a strongly enhanced ozone loss rate in the presence of TBA, which is attributed to an enhanced surface reaction rate. We used liquid jet XPS to obtain detailed chemical composition information from the aqueous-solution-vapor interface of mixed aqueous solutions containing bromide or bromide and chloride with and without TBA surfactant. Core level spectra of Br 3d, C 1s, Cl 2p, N 1s, and O 1s were used for this comparison. A model was developed to account for the attenuation of photoelectrons by the carbon-rich layer established by the TBA surfactant. We observed that the interfacial density of bromide is increased by an order of magnitude in solutions with TBA. The salting-out of TBA in the presence of 0.55 M sodium chloride is apparent. The increased interfacial bromide density can be rationalized by the association constants for bromide and chloride to form ion-pairs with TBA. Still, the interfacial reactivity is not increasing simply proportionally with the increasing interfacial bromide concentration in response to the presence of TBA. The steady state concentration of the bromide ozonide intermediate increases by a smaller degree, and the lifetime of the intermediate is 1 order of magnitude longer in the presence of TBA. Thus, the influence of cationic surfactants on the reactivity of bromide depends on the details of the complex environment at the interface.
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Affiliation(s)
- Shuzhen Chen
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
- Institute
of Atmospheric and Climate Sciences, ETH
Zürich, 8006 Zürich, Switzerland
| | - Luca Artiglia
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
| | - Fabrizio Orlando
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
| | - Jacinta Edebeli
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
- Institute
of Atmospheric and Climate Sciences, ETH
Zürich, 8006 Zürich, Switzerland
| | - Xiangrui Kong
- Center
for Atmospheric Research, University of
Oulu, P.O. Box 4500, 90014 Oulu, Finland
| | - Huanyu Yang
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
- Institute
of Atmospheric and Climate Sciences, ETH
Zürich, 8006 Zürich, Switzerland
| | - Anthony Boucly
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
| | - Pablo Corral Arroyo
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
| | - Nønne Prisle
- Center
for Atmospheric Research, University of
Oulu, P.O. Box 4500, 90014 Oulu, Finland
| | - Markus Ammann
- Laboratory
of Environmental Chemistry, Paul Scherrer
Institute, 5232 Villigen, Switzerland
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Hyttinen N, Prisle NL. Improving Solubility and Activity Estimates of Multifunctional Atmospheric Organics by Selecting Conformers in COSMO therm. J Phys Chem A 2020; 124:4801-4812. [PMID: 32420745 PMCID: PMC7297446 DOI: 10.1021/acs.jpca.0c04285] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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We
estimated aqueous solubilities and activity coefficients of
atmospherically relevant highly oxidized multifunctional organic compounds
in binary mixtures with water at temperatures between 278.15 and 338.15
K, using the COSMOtherm program. Physicochemical
properties of organic aerosol constituents are needed in the modeling
of atmospheric aerosol processes. As experimental data are often impossible
to obtain, reliable estimates from theoretical approaches are a promising
path to fill this gap. We investigated the effect of intramolecular
hydrogen bonds on the estimation of these condensed-phase properties,
attempting to improve the agreement between experimental and estimated
values. Citric, tartaric, malic, and maleic acids, which are often
used in atmospheric models as representatives of oxidized compounds,
were selected to benchmark our calculations. In addition, we estimated
aqueous solubilities and activity coefficients of α-pinene-derived
organosulfates and highly oxidized isoprene-derived organic compounds,
for which no experimental data are available. Our results indicate
that the absolute aqueous solubility and activity coefficient estimates
of citric, tartaric, malic, and maleic acids, and likely other multifunctional
organics, can be improved significantly by selecting conformers on
the basis of their intramolecular hydrogen bonding in COSMOtherm calculations.
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Affiliation(s)
- Noora Hyttinen
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
| | - Nønne L Prisle
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
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McFall AS, Johnson AW, Anastasio C. Air-Water Partitioning of Biomass-Burning Phenols and the Effects of Temperature and Salinity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3823-3830. [PMID: 32162913 DOI: 10.1021/acs.est.9b06443] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Biomass burning (BB) emits organic gases that, with chemical aging, can form secondary organic aerosol (SOA) in both the gas and aqueous phases. One class of biomass-burning emissions, phenols, are of interest because they react rapidly in the aqueous phase to efficiently form SOA, which might affect climate and human health. However, while measurements exist for the air-water partitioning constants of some simple phenols, Henry's law constants (KH) are unknown for more complex BB phenols. In this work, we use a custom-built apparatus to measure KH for a suite of biomass-burning phenols that span a wide range of air-water partitioning coefficients. Comparing our measurements to predicted values from EPI Suite shows that this model consistently overestimates KH unless a suitable measured phenol KH value is included to adjust the calculations. In addition, we determine the effect of five salts on phenol partitioning by measuring the Setschenow coefficients (KS). Across the eight phenols we examined, values of KS depend primarily on salt identity and descend in the order (NH4)2SO4 > NaCl > NH4Cl ≥ KNO3 > NH4NO3. Lastly, we use our KH and KS results to discuss the aqueous processing of biomass-burning phenols in cloud/fog water versus aerosol liquid water.
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Affiliation(s)
- Alexander S McFall
- Department of Land, Air, and Water Resources, University of California, Davis, Davis, California 95670, United States
| | - Alex W Johnson
- Department of Land, Air, and Water Resources, University of California, Davis, Davis, California 95670, United States
| | - Cort Anastasio
- Department of Land, Air, and Water Resources, University of California, Davis, Davis, California 95670, United States
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Lin JJ, Kristensen TB, Calderón SM, Malila J, Prisle NL. Effects of surface tension time-evolution for CCN activation of a complex organic surfactant. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:271-284. [PMID: 31912080 DOI: 10.1039/c9em00426b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The physical processes and time scales underlying the evolution of surface tension in atmospheric solution droplets are largely unaccounted for in present models describing cloud droplet formation. Adsorption of surface-active molecules at the surface of a solution droplet depresses the droplet surface tension but also depletes solute from the droplet bulk, which have opposing and sometimes canceling effects in cloud droplet formation. In this work, we study the effect of time-evolving surface tension for cloud droplet activation of particles composed of Nordic Aquatic Fulvic Acid (NAFA) mixed with sodium chloride (NaCl). We model the formation of cloud droplets using Köhler theory with surface tension depression and bulk/surface partitioning evaluated from two different thermodynamic surface models. Continuous ternary parameterizations were constructed from surface tension measurements of macroscopic droplets at different time steps after the formation of a droplet surface. The predicted results are compared to previous measurements of mixed NAFA-NaCl cloud condensation nuclei (CCN) activity and a bulk solution model that does not take the NAFA bulk/surface partitioning equilibrium into account. Whereas the bulk model shows a trend in cloud droplet formation following that of macroscopic surface tension depression with time, the variation with time essentially disappears when bulk/surface partitioning is taken explicitly into account during droplet activation. For all equilibrium time steps considered, the effect of surface tension depression in the NAFA-NaCl system is counteracted by the depletion of solute from the finite-sized droplet bulk phase. Our study highlights that a comprehensive data set is necessary to obtain continuous parameterizations of surface tension and other solution properties required to fully account for the bulk/surface partitioning in growing droplets. To our knowledge, no similar data set currently exists for other aqueous organic systems of atmospheric interest. Additional work is necessary to deconvolve the effects of bulk/surface partitioning in the context of time-evolution on cloud droplet activation and to determine whether the results presented here can be further generalized.
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Affiliation(s)
- Jack J Lin
- Nano and Molecular Systems Research Unit, University of Oulu, P. O. Box 3000, Oulu, FI-90014, Finland.
| | | | - Silvia M Calderón
- Nano and Molecular Systems Research Unit, University of Oulu, P. O. Box 3000, Oulu, FI-90014, Finland.
| | - Jussi Malila
- Nano and Molecular Systems Research Unit, University of Oulu, P. O. Box 3000, Oulu, FI-90014, Finland.
| | - Nønne L Prisle
- Nano and Molecular Systems Research Unit, University of Oulu, P. O. Box 3000, Oulu, FI-90014, Finland.
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7
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Michailoudi G, Hyttinen N, Kurtén T, Prisle NL. Solubility and Activity Coefficients of Atmospheric Surfactants in Aqueous Solution Evaluated Using COSMO therm. J Phys Chem A 2020; 124:430-443. [PMID: 31829596 DOI: 10.1021/acs.jpca.9b09780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fatty acids (CH3(CH2)n-2COOH) and their salts are an important class of atmospheric surfactants. Here, we use COSMOtherm to predict solubility and activity coefficients for C2-C12 fatty acids with even number of carbon atoms and their sodium salts in binary water solutions and also in ternary water-inorganic salt solutions. COSMOtherm is a continuum solvent model implementation which can calculate properties of complex systems using quantum chemistry and thermodynamics. Calculated solubility values of the organic acids in pure water are in good agreement with reported experimental values. The comparison of the COSMOtherm-derived Setschenow constants for ternary solutions comprising NaCl with the corresponding experimental values from the literature shows that COSMOtherm overpredicts the salting out effect in all cases except for the solutions of acetic acid. The calculated activity and mean activity coefficients of fatty acids and fatty acid sodium salts, respectively, show deviation of the systems from ideal solution. The computed mean activity coefficients of the fatty acid salts in binary systems are in better agreement with experimentally derived values for the organic salts with longer aliphatic chain (C8-C10). The deviation of the solutions from ideality could lead to biased estimations of cloud condensation nuclei number concentrations if not considered in Köhler calculations and cloud microphysics.
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Affiliation(s)
- Georgia Michailoudi
- Nano and Molecular Systems Research Unit , University of Oulu , P.O. Box 3000, FI-90014 Oulu , Finland
| | - Noora Hyttinen
- Nano and Molecular Systems Research Unit , University of Oulu , P.O. Box 3000, FI-90014 Oulu , Finland.,Department of Chemistry and Institute for Atmospheric and Earth System Research (INAR) , University of Helsinki , P.O. Box 55, FI-00014 Helsinki , Finland
| | - Theo Kurtén
- Department of Chemistry and Institute for Atmospheric and Earth System Research (INAR) , University of Helsinki , P.O. Box 55, FI-00014 Helsinki , Finland
| | - Nønne L Prisle
- Nano and Molecular Systems Research Unit , University of Oulu , P.O. Box 3000, FI-90014 Oulu , Finland
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