University of Oulu

Hyttinen, N., Heshmatnezhad, R., Elm, J., Kurtén, T., and Prisle, N. L.: Technical note: Estimating aqueous solubilities and activity coefficients of mono- and α,ω-dicarboxylic acids using COSMOtherm, Atmos. Chem. Phys., 20, 13131–13143,, 2020

Technical note : estimating aqueous solubilities and activity coefficients of mono- and α,ω-dicarboxylic acids using COSMOtherm

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Author: Hyttinen, Noora1,2; Heshmatnezhad, Reyhaneh1; Elm, Jonas3;
Organizations: 1Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
2Department of Chemistry and Institute for Atmospheric and Earth System Research (INAR), University of Helsinki,P.O. Box 55, 00014 Helsinki, Finland
3Department of Chemistry and iClimate, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3 MB)
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Language: English
Published: Copernicus Publications, 2020
Publish Date: 2020-11-11


We have used the COSMOtherm program to estimate activity coefficients and solubilities of mono- and α,ω-dicarboxylic acids and water in binary acid–water systems. The deviation from ideality was found to be larger in the systems containing larger acids than in the systems containing smaller acids. COnductor-like Screening MOdel for Real Solvents (COSMO-RS) underestimates experimental monocarboxylic acid activity coefficients by less than a factor of 2, but experimental water activity coefficients are underestimated more especially at high acid mole fractions. We found a better agreement between COSMOtherm-estimated and experimental activity coefficients of monocarboxylic acids when the water clustering with a carboxylic acid and itself was taken into account using the dimerization, aggregation, and reaction extension (COSMO-RS-DARE) of COSMOtherm. COSMO-RS-DARE is not fully predictive, but fit parameters found here for water–water and acid–water clustering interactions can be used to estimate thermodynamic properties of monocarboxylic acids in other aqueous solvents, such as salt solutions. For the dicarboxylic acids, COSMO-RS is sufficient for predicting aqueous solubility and activity coefficients, and no fitting to experimental values is needed. This is highly beneficial for applications to atmospheric systems, as these data are typically not available for a wide range of mixing states realized in the atmosphere, due to a lack of either feasibility of the experiments or sample availability. Based on effective equilibrium constants of different clustering reactions in the binary solutions, acid dimer formation is more dominant in systems containing larger dicarboxylic acids (C₅–C₈), while for monocarboxylic acids (C₁–C₆) and smaller dicarboxylic acids (C₂–C₄), hydrate formation is more favorable, especially in dilute solutions.

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Series: Atmospheric chemistry and physics
ISSN: 1680-7316
ISSN-E: 1680-7324
ISSN-L: 1680-7316
Volume: 20
Pages: 13131 - 13143
DOI: 10.5194/acp-20-13131-2020
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Funding: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program, project SURFACE (grant agreement no. 717022); the Academy of Finland (grant nos. 308238, 314175, 315600 and 335649); the Swedish Research Council Formas (project no. 2018-01745-COBACCA); and the Independent Research Fund Denmark (grant no. 9064-00001B). Open access funding provided by Helsinki University Library.
EU Grant Number: (717022) SURFACE - The unexplored world of aerosol surfaces and their impacts.
Academy of Finland Grant Number: 308238
Detailed Information: 308238 (Academy of Finland Funding decision)
335649 (Academy of Finland Funding decision)
314175 (Academy of Finland Funding decision)
Copyright information: © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.