Europhys. Lett.
Volume 74, Number 5, June 2006
Page(s) 854 - 860
Section Condensed matter: structural, mechanical and thermal properties
Published online 26 April 2006
Europhys. Lett., 74 (5), pp. 854-860 (2006)
DOI: 10.1209/epl/i2006-10030-0

Surface tension of electrolyte solutions: Comparing the effects of ionic dispersion forces and solvation

S. A. Edwards and D. R. M. Williams

Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University - ACT 0200, Australia

received 12 January 2006; accepted in final form 30 March 2006
published online 26 April 2006

The influence of salt on the surface tension of water is yet to be understood. We derive approximate analytical expressions for the influence of two different ion-specific effects on the surface tension of an electrolyte: the dispersion interaction between the ions and the air-water interface, and the change in solvation energy of the ions as they approach the interface. These formulae provide a simple means of comparing the relative importance of the two effects. We carry out such a comparison for the case of 1$\un{M}$ $\chem{NaCl}$, and find that solvation is the dominant effect.

68.03.Cd - Surface tension and related phenomena.
82.45.Gj - Electrolytes.

© EDP Sciences 2006