Structure of nonpolarizable water/nitrobenzene interface: Potential distribution, ion adsorption, and interfacial tension

Vladislav S. Markin, Alexander G. Volkov, Maya I. Volkova-Gugeshashvili

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Adsorption of hydrophobic and hydrophilic ions at the nonpolarizable interface between two immiscible electrolyte solutions was investigated. The results were analyzed in three different models: (i) Gouy-Chapman model, (ii) ions as hard spheres, and (iii) ion pair formation at the interface. In the Gouy-Chapman model, an analytical expression for the interfacial tension was obtained. It predicts that interfacial tension should be proportional to the square root of the electrolyte concentration, which does not agree with experimental data. Modeling ions as hard spheres only slightly improves the agreement. The third model of interfacial ion pairing as the main origin of adsorption was analyzed using the amphiphilic isotherm (Markin-Volkov isotherm). A good agreement between ion-pairing theory and experimental values was achieved. The MV isotherm takes into account the limited number of adsorption sites, final size of molecules, complex formation at the interface, and interaction between adsorbed particles. The analysis revealed repulsion between adsorbed tetraalkylammonium ions at the nitrobenzene/water interface and demonstrated linear dependence between adsorption site area and the size of a molecule.

Original languageEnglish (US)
Pages (from-to)16444-16454
Number of pages11
JournalJournal of Physical Chemistry B
Volume109
Issue number34
DOIs
StatePublished - Sep 1 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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