Interfacial aggregation of a nonionic surfactant: Effect on the stability of silica suspensions
- CNRS, Marseille (France). Centre de thermodynamique et Microcalorimetrie
Nonionic surfactants are in widespread use in technological applications such as flotation, detergency, suspension stabilization (paints, ceramic preparation, pharmaceuticals, cosmetics), and enhanced oil recovery. The adsorption of the nonionic surfactant TX 100 in two silica suspensions (Ludox HS40 and Syton W30) has been studied with the aim of relating the structure of the adsorbed layer to the stability of the suspension. First, a thermodynamic study based on the determination of adsorption isotherms and displacement enthalpies as a function of pH and solid/liquid ratio was carried out and lead to the conclusion that such a surfactant forms micelle-like aggregates on the silica surface. Then, a stability study based on visual observation, turbidimetry, and particle size determination (by photon correlation spectroscopy) was performed in order to determine the TX 100 concentration range in which flocculation occurs. Considering that the surface is covered with micelle-like aggregates in the flocculation range and that the [zeta]-potential (determined by microelectrophoresis) has varied only slightly at the onset of flocculation, it is concluded that the flocculation mechanism is a bridging of particles by surface micelles. This bridging of particles by aggregates similar in size and shape could be an explanation of the presence, in such systems, of optimum flocculation at half surface coverage.
- OSTI ID:
- 7036681
- Journal Information:
- Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 165:1; ISSN 0021-9797; ISSN JCISA5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ADSORPTION
AGGLOMERATION
AQUEOUS SOLUTIONS
CHALCOGENIDES
DISPERSIONS
INTERFACES
LAYERS
MICELLAR SYSTEMS
MINERALS
MIXTURES
MORPHOLOGY
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POTENTIALS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOLUTIONS
SORPTION
SORPTIVE PROPERTIES
SURFACE POTENTIAL
SURFACE PROPERTIES
SURFACTANTS
THERMODYNAMICS