The interaction of solid surfaces in aqueous systems

Abstract

Abstract:The interaction between two high-grade polished fused silica plates separated by a thin layer of aqueous LiC1, NaCI and KCI solution, respectively, was determined by means of a selfdeveloped method. Concerning the repulsion created by overlap of the electrical double layers excellent agreement with the DLVO theory down to separation of about 5 nm were found. For still smaller separations a relatively strong additional repulsion arises which according to experimental evidence might be assigned to the overlap of hydration layers emanating chiefly from the alkali metal halide ions adsorbed onto the silica surfaces. Our results agree well with those obtained by Israelachvili et al. and Pashley, who used mica sheets.

Dispersion of Silica Fines in Water–Ethanol Suspensions

“…A repulsive hydration force has been observed between mica surfaces in aqueous solutions above some critical electrolyte concentration (10,11) and between glass threads and silica plates in aqueous solutions (12,13). More evidence for such an additional force has come from later studies (14)(15)(16)(17).…”

Influence of Surface Wettability on Adsorption Isotherms of Water Vapor

“…So, the results of calculation of equilibrium contact of Eq. [9] shows that partial wetting takes place at the angles for the adopted parameters of the isotherm (9) are following conditions: K 1 ú K 2 , and l 1 õ l 2 . The calculated limited by u 0 values lower than 25Њ.…”

“…[6] used for describing the effect of structural repulsion forces in thin films and interlayers (1,(3)(4)(5)(8)(9)(10)(11)(12). In the case of a hydrophilic surface P 0 ú 0, and h m is on the order of bulk The same result is obtained when the function h(P) Å h m ln(P/P 0 ) was directly included in Eq.…”

Colloidal crystals and water: Perspectives on liquid–solid nanoscale phenomena in wet particulate media

“…Such adsorption excess has been attempted to explain by adding terms to  [6,92,93] although they cannot not fully explain the observations and their precise physical origin remains elusive. These contributions are principally electrostatic (double-layer forces due to surface ionization) or structural (hydration forces caused by ordering of the first water layers), while the presence of surface contaminants [92,98] must also be considered. In particular, the initial wetting of the silica can lead to surface ionization (and to subsequent electrical double layer) due to the silanol groups, which can also favor structuring of the adsorbed water layers [94].…”

“…Mutual repulsion between hydrated solid surfaces like silica is long known and typically described by double-layer forces and, at small distances, also by the shorter-range hydration force [1]. Hydration repulsion has been found to dominate at separations of 1−5 nm in a number of systems [98,120,121]. Thus, hydration forces may justify the nonclose CC packing but, due to their short range, would not explain such large  values, although hydration layers as thick as 7−8 nm have been reported in a suspension of colloidal silica spheres [122].…”