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Published May 4, 2006 | public
Journal Article

Thermodynamic Models of Aqueous Solutions Containing Inorganic Electrolytes and Dicarboxylic Acids at 298.15 K. 1. The Acids as Nondissociating Components


Atmospheric aerosols contain a significant fraction of water-soluble organic compounds, including dicarboxylic acids. Water activities at ∼298.15 K (including data for highly supersaturated solutions) of oxalic, malonic, succinic, glutaric, maleic, malic, and methyl succinic acids are first correlated as a function of concentration, treating the acids as nondissociating components. Methods proposed by Clegg et al. (J. Aerosol. Sci. 2001, 32, 713−738), and by Clegg and Seinfeld (J. Phys. Chem. A 2004, 108, 1008−1017) for estimating water activities and solute activity coefficients in aqueous mixtures containing both electrolytes and uncharged solutes are then evaluated from comparisons with literature data. These data include water activities, solubilities, and determinations of the eutonic points of solutions containing up to five acids, and solutions containing one or more acids and the salts (NH_4)_2SO_4, NH_4NO_3, or NaCl. The extended Zdanovskii−Stokes−Robinson approach of Clegg and Seinfeld yields the more accurate predictions for aqueous mixtures containing dicarboxylic acids only, and for aqueous mixtures of the acids and salts (though by a lesser margin). A number of hybrid modeling approaches, which contain elements of both methods, are outlined.

Additional Information

© 2006 American Chemical Society. Received 26 October 2005. Published online 4 April 2006. Published in print 1 May 2006. This work was supported by U.S. Environmental Protection Agency grant RD-83107501 and Cooperative Agreement CR-831194001, and by the Natural Environment Research Council of the U.K. (as a part of the Tropospheric Organic Chemistry Experiment). The work has not been subject to the U.S. EPA's peer and policy review, and does not necessarily reflect the views of the Agency and no official endorsement should be inferred. The authors would like to thank all those who made available their experimental data, and the Atmospheric Modeling Division of U.S. EPA for hosting S.L.C. while carrying out this study. Note Added in Proof. Many of the data used in this work have been tabulated and are available at:  http:// www.uea.ac.uk/∼e770/aim.html.

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