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Research article - Peer-reviewed, 2014

Succinic acid in aqueous solution: connecting microscopic surface composition and macroscopic surface tension

Werner, Josephina; Julin, Jan; Dalirian, Maryam; Prisle, Nønne; Öhrwall, Gunnar; Persson, Ingmar; Björneholm, Olle; Riipinen, Ilona;

Abstract

The water-vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. It was found that succinic acid has a considerably higher propensity to reside in the aqueous surface region than its deprotonated form, which is effectively depleted from the surface due to the two strongly hydrated carboxylate groups. From both XPS experiments and MD simulations a strongly increased concentration of the acid form in the surface region compared to the bulk concentration was found and quantified. Detailed analysis of the surface of succinic acid solutions at different bulk concentrations led to the conclusion that succinic acid saturates the aqueous surface at high bulk concentrations. With the aid of MD simulations the thickness of the surface layer could be estimated, which enabled the quantification of surface concentration of succinic acid as a multiple of the known bulk concentration. The obtained enrichment factors were successfully used to model the surface tension of these binary aqueous solutions using two different models that account for the surface enrichment. This underlines the close correlation of increased concentration at the surface relative to the bulk and reduced surface tension of aqueous solutions of succinic acid. The results of this study shed light on the microscopic origin of surface tension, a macroscopic property. Furthermore, the impact of the results from this study on atmospheric modeling is discussed.

Published in

Physical Chemistry Chemical Physics

2014, volume: 16, number: 39, pages: 21486-21495

Authors' information

Werner, Josephina
Uppsala University
Werner, Josephina
Swedish University of Agricultural Sciences, The Department of Chemistry and Biotechnology
Julin, Jan
Stockholm University
Dalirian, Maryam
Stockholm University
Prisle, Nønne
University of Helsinki
Öhrwall, Gunnar
Lund University
Swedish University of Agricultural Sciences, The Department of Chemistry and Biotechnology
Björneholm, Olle
Uppsala University
Riipinen, Ilona
Carnegie Mellon University

UKÄ Subject classification

Physical Chemistry

Publication Identifiers

DOI: https://doi.org/10.1039/c4cp02776k

URI (permanent link to this page)

https://res.slu.se/id/publ/61208