Determination of Particle Size Distribution and Electrokinetic Potential of Phyllosilicate Powders by Photon Correlation Spectroscopy

The issues of monitoring and controlling the particle size distribution and electrokinetic potential of phyllosilicate powders by the method of photon correlation spectroscopy are considered. Stable standardized colloidal solutions of powders of kaolinite and montmorillonite clays from deposits of the Orenburg region have been analyzed. The highest quality solution with objects accessible for observation was obtained near the isoelectric cleavage point of minerals (solution pH = 6.5). The modal effective diameters of non-agglomerated particles of kaolinite and montmorillonite have been determined. The formation of ultra- and microaggregates of micrometer-sized particles has been observed, interacting both along the basal planes and according to the “basal plane – lateral cleavage site” arrangement. The dependence of the electrokinetic potential of a suspension of kaolinite and montmorillonite particles on the pH of the medium has been measured. It is shown that the behavior of both types of particles in an electric field in a suspension with pH > 5 is practically the same, and the main differences manifest in an acidic medium: the isoelectric point for kaolinite is close to pH = 2, and for montmorillonite, to pH = 3.5. The results of the study will be useful for creating adsorbents based on natural phyllosilicates.