Electrokinetic and direct force measurements between silica and mica surfaces in dilute electrolyte solutions

Patrick G. Hartley, Ian Larson, Peter J. Scales

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An atomic force microscope has been used to study the forces between a silica sphere in the colloidal size range and silica or mica flat surfaces as a function of distance of separation. At low ionic strength, independent electrokinetic measurements (ζ potentials) of both the spheres (by electrophoresis) and flat surfaces (by streaming potential) under the same conditions show excellent agreement with the diffuse double layer potentials derived from the force data using conventional DLVO theory. At higher ionic strength, the electrokinetically derived potentials were found to deviate from those derived from the fitted atomic force microscopy data, and a short range steric type repulsion was observed between the surfaces, the magnitude of which increased with decreasing pH.

Original languageEnglish
Pages (from-to)2207-2214
Number of pages8
Issue number8
Publication statusPublished - 16 Apr 1997
Externally publishedYes

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