Electrosurface properties of kaolin and bentonite particles in solutions of electrolytes and surfactants

S. Bárány, R. Meszaros, R. Taubaeva, K. Musabekov

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The influence of pH and KCl, CaCl2, AlCl3, sodium dodecyl sulfate, and cetyltrimethylammonium bromide (CTAB) concentrations on electrokinetic potential ζ of particles and the electrical conductivity of aqueous kaolin and bentonite suspensions has been studied. At “natural” pH values of the suspensions (7.2–7.4), the ζ potential of bentonite is much higher (–45 mV) than that of kaolin (–20 mV), and this difference takes place in a wide pH range (2–11). In both cases, a rise in pH leads to an increase in the absolute values of ζ due to the enhanced dissociation of surface OH groups. Charge reversal is observed at pH of approximately 2 and pH 2.5 for kaolin and bentonite, respectively. The dependence of the ζ potential of the particles on KCl concentration passes through a maximum, while the addition of CaCl2 and AlCl3 causes a substantial reduction in ζ and particle charge reversal, respectively. An increase in CTAB concentration C in a suspension leads to a decrease in the negative ζ values followed by particle charge reversal, with the ζ(C) curve tending to reach a plateau. It has been shown that the initial regions of the dependences of the relative electrical conductivities of the suspensions on the volume fraction of the solid phase are almost linear, with their slopes decreasing with a rise in electrolyte concentration. Hence, the contribution of the surface conductivity to the total suspension conductivity decreases with a rise in the ionic strength of a solution. The values of the electrokinetic charge calculated from the data on the ζ potential, i.e., the charge of the slipping plane, have appeared to be one to two orders of magnitude lower than the surface charges of the minerals. This finding suggests that counterions are predominantly located in the hydrodynamically motionless part of the electrical double layer.

Original languageEnglish
Pages (from-to)692-697
Number of pages6
JournalColloid Journal
Volume77
Issue number6
DOIs
Publication statusPublished - Nov 1 2015

Fingerprint

Bentonite
Kaolin
bentonite
Surface-Active Agents
Electrolytes
Suspensions
Surface active agents
surfactants
electrolytes
electrokinetics
Sodium dodecyl sulfate
Surface charge
Ionic strength
bromides
Volume fraction
Minerals
conductivity
electrical resistivity
Sodium Dodecyl Sulfate
sodium sulfates

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry
  • Surfaces and Interfaces

Cite this

Electrosurface properties of kaolin and bentonite particles in solutions of electrolytes and surfactants. / Bárány, S.; Meszaros, R.; Taubaeva, R.; Musabekov, K.

In: Colloid Journal, Vol. 77, No. 6, 01.11.2015, p. 692-697.

Research output: Contribution to journalArticle

Bárány, S. ; Meszaros, R. ; Taubaeva, R. ; Musabekov, K. / Electrosurface properties of kaolin and bentonite particles in solutions of electrolytes and surfactants. In: Colloid Journal. 2015 ; Vol. 77, No. 6. pp. 692-697.
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