Electrical Double Layer Structure Revisited via a Surface Force Apparatus: Mica Interfaces in Lithium Nitrate Solutions
✍ Scribed by Victor E. Shubin; Patrick Kékicheff
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 1007 KB
- Volume
- 155
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
The force as a function of separation is measured between two mica surfaces immersed in lithium nitrate aqueous solutions over wide concentration and (\mathrm{pH}) ranges. In most cases the forcedistance profiles are in good agreement with DLVO theory. However, at short separations deviations from DLVO prediction are observed. Their possible sources, and in particular the socalled hydration force, are discussed. The exponentially decaying parts of force profiles, yielding information about the (\Psi_{d}) potentials, are analyzed using a conventional electrical double layer (e.d.I.)/charge formation model (triple-layer model). By assuming a shift of the diffuse layer boundary on the order of a diameter of one hydrated ion away from the mica-mica contact surface, the obtained (\Psi_{d})-potentials can be described together with ion adsorption data reported previously by (P). M. Claesson et al. (J. Colloid Interface Sci. 109, 31 (1986)). A set of parameters reflecting the charging properties of the mica/water interface and the spacial organization of the e.d.I. have been estimated. Contact adhesion measurements allow the assumption that in primary contact, the mica surfaces are separated by a single layer of hydrated ions, which share their hydration water with the mica surfaces ("bridging effect”). ๑ 1993 Academic Press, Inc.