Abstract
The phenomena of electrolytes affecting the surface tension of aqueous solutions and producing measurable surface potentials are reviewed in the light of recent studies of them. The factual information presented includes the molar ionic surface tension increments ki = lim(ci → 0)(dσ / dci) of many ions and the surface potential increments ∆ χ = χE − χW of electrolytes involving the cations H+, Na+, K+, and NH4+ and various anions. Gaps in the data that invite filling and inconsistencies in reported data are pointed out. Correlations of ki with several properties of the ions that should be relevant to their specific effects: their sizes, quantities representing their polarizabilities, their effects on the structure of the water and the binding of water molecules by them, are presented. Correlations of the surface potential increment ∆ χ with the electrolyte surface tension increments and with the differences between the cation and anion increments are shown. Models recently proposed for the rationalization of the observed phenomena and relevant theoretical developments are shown and discussed. The paradox of hydrogen ions not promoting significant charge separation at the interface but yielding large surface potentials is emphasized.
Original language | English |
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Pages (from-to) | 94-99 |
Number of pages | 6 |
Journal | Current Opinion in Colloid and Interface Science |
Volume | 23 |
DOIs | |
State | Published - 1 Jun 2016 |
Bibliographical note
Publisher Copyright:© 2016 Elsevier Ltd
Keywords
- Aqueous electrolytes
- Ion depletion/enrichment at the surface
- Specific ion effects
- Surface electric double layer
- Surface potential
- Surface tension increment