Modeling effects of pH and counterions on surfactant adsorption at the oxide/water interface
- Univ. of Oklahoma, Norman, OK (United States)
The adsorption of surfactants on minerals is important in areas such as enhanced oil recovery, surfactant-enhanced soil remediation, formation of organic thin films, ore flotation, wetting, adhesion, detergency, and dispersion stability. A model is presented that describes the effect of pH on the adsorption of an isomerically pure anionic surfactant species at a mineral oxide/water interface. A site-binding model, to account for effects of pH, surface heterogeneities, and counterions, is incorporated into a patchwise, phase-separation modeling approach, making it possible to predict both the surface charge and the counterion association beneath an adsorbed surfactant aggregate. Parameters for the site binding model on {alpha}-alumina are obtained from experimental surface charge measurements. The formation of both local monolayers (hemimicelles) and bilayers (admicelles) is allowed, although the isotherms studied in this paper are fit by parameter values that predict admicelle formation only. The model is able to predict experimental measurements of the adsorption of an isomerically pure, anionic surfactant species on {alpha}-alumina as a function of pH. It reproduces several previously unexplained experimental observations; in particular, it offers an explanation for the observation of significant adsorption of anionic surfactant above the point of zero charge (pzc) of a mineral oxide surface.
- DOE Contract Number:
- AC22-85BC10845
- OSTI ID:
- 377727
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 35, Issue 9; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Surfactant adsorption and chromatographic movement with application in enhanced oil recovery
Mineral-Surfactant Interaction for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery