Ionic Mobility and Hydration Energies in Montmorillonite Clay

The structure of swelling clays consists of a framework composed of negatively charged clay platelets and interlayer cations. Swelling clays present different behaviors as a function of the nature of the interlayer cation: the swelling capacity and the adsorption ability are strongly modified. Therefore the determination of the properties of these interlayer cations is prerequisite to understand the features of the clay swelling and the exchange properties. In this paper, we propose to study the interactions between the interlayer cations and the clay framework by determining the activation energy for the cation motion. This cation displacement is observable under the action of an external electrical field during conductivity measurements. Indeed, it has already been shown that the complex impedance spectroscopy (CIS) is a well-adapted tool to study the energy related to the motion of an electric charge. We propose to determine energy values for the cation motions by electrical conductivity measurements p...