Thermodynamic study on the adsorption of sodium chloride at the water/hexane interface

Norihiro Ikeda, Makoto Aratono, Kinsi Motomura

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Abstract

The negative adsorption of sodium chloride at the water/hexane interface has been investigated by measuring interfacial tension as a function of pressure and concentration. By analyzing the results thermodynamically, the interfacial densities and the distance between the two dividing planes introduced so as to make the excess numbers of moles of water and hexane zero were evaluated. The results lead us to the view that the ions and hexane molecules distribute further apart from each other in the interfacial region. Furthermore, the volume of interface formation, Δυ, was evaluated; Δυ was found to be positive and independent of the concentration. In addition, the entropy, Δυ, and energy, Δυ, of interface formation were evaluated by measuring interfacial tension as a function of temperature. It was seen that Δυ, like Δυ, is independent of concentration, whereas Δs decreases slightly with increasing molality. This discrepancy was explained as resulting from the contribution of the entropy of mixing.

Original languageEnglish
Pages (from-to)208-215
Number of pages8
JournalJournal of Colloid And Interface Science
Volume149
Issue number1
DOIs
Publication statusPublished - Mar 1 1992

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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