Role of Counterion in the Adsorption Behavior of 1:1 Ionic Surfactants at Fluid Interfaces-Adsorption Properties of Alkali Perfluoro-n-octanoates at the Air/Water Interface
Equilibrium surface tension (σe) versus bulk concentration (c) isotherms of aqueous, surface-chemically pure solutions of various alkali perfluoro-n-octanoates were measured at 295 K. These 1:1 ionic surfactant systems belong to the pseudo nonionic ones. Evaluating the different σe vs log c isotherm...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 33(2017), 39 vom: 03. Okt., Seite 10216-10224 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2017
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Equilibrium surface tension (σe) versus bulk concentration (c) isotherms of aqueous, surface-chemically pure solutions of various alkali perfluoro-n-octanoates were measured at 295 K. These 1:1 ionic surfactant systems belong to the pseudo nonionic ones. Evaluating the different σe vs log c isotherms by basic adsorption equations reveals that they follow ideal surface behavior. The novelty of this investigation exists in the fact that the surface area demand per molecule adsorbed calculated from the experimental σe vs log c isotherms is identical to that of the hydrated alkali cation. Thus, as long as the counterion's cross-sectional area is greater than that of its amphiphilic anion, the amphiphile's total surface area demand will exclusively be governed by that of its alkali counterion. This, in turn, means that the counterion is nonrandomly bound to the amphiphilic anion in the adsorption layer. Furthermore, the size of the hydrated alkali counterion in the adsorption layer does not differ from that in the bulk phase |
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| Beschreibung: | Date Completed 31.07.2018 Date Revised 31.07.2018 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/acs.langmuir.7b00786 |