Polarizability and Electrosurface Properties of Colloidal Graphite Particles in Aqueous KCl Solutions

Abstract

Results of studying the electric polarizability of colloidal graphite particles in an aqueous 1 : 1 electrolyte solution at frequencies of 100 Hz to 2.5 MHz have been presented. The polarizability anisotropy, surface conductivity, and electrokinetic potential of graphite particles have been investigated in aqueous KCl solutions with concentrations lower than 0.2 mmol/L. The dispersion of polarizability anisotropy of graphite particles has been determined by the electrooptical method, while their electrokinetic potential has been measured by laser Doppler microelectrophoresis. It has been shown that, at low electric field frequencies, the particles are polarized as dielectric ones. The theory of polarizability of dielectric particles has been employed to calculate the surface conductivity of graphite particles as a function of KCl concentration. As the frequency is increased, the mechanism of conductive particle polarizability begins to dominate over the mechanism of dielectric particle polarizability. In the aforementioned range of KCl concentrations, the electrokinetic potential of the particles varies significantly weaker than their polarizability and lies in a range of 30–36 mV.