Spectral induced polarization of Na-montmorillonite dispersions

Abstract : Montmorillonite has remarkable adsorption properties because of its high specific surface area and surface charge density. Its surface charge distribution is also anisotropic. The basal faces have a negative and permanent surface charge due to isomorphic substitutions in the crystal and the edge faces have a pH-dependent surface charge due to amphoteric surface sites. We propose low-frequency complex impedance measurements of Na-Mt dispersions in the unexplored frequency range [Hz kHz] to get information on surface charge distribution, size and shape of Na-Mt dispersions at various particles concentrations (weight fractions 0.5 to 5%), salinities (from 10-4 to 10-2 M NaCl), and pH (5 to 10).