Analysis of the colloidal properties of different clay minerals: impact on barrier performance

Abstract

Cadmium is one of the heavy metals of concern, both from the point of view of public health and environmental safety, because it is a toxic element, bio-accumulative and persistent. Therefore, it is considered of vital importance to develop materials and methodologies that favour its retention and removal. In this study, the retention of cadmium in a nanoparticulate oxide, -Al2O3 was analyzed. A complete experimental sorption study in a wide range of chemical was carried out, to elucidate the main retention mechanisms. This study is part of a broader work, in which the sorption behaviour of mixed systems, including clay materials that would form a geochemical barrier, was analysed. For analogy with previous studies of retention of contaminants in clays, a non-electrostatic surface complexation model, mechanistic and thermodynamic-based, was selected to describe Cd retention on -Al2O3. The developed model was tested on experimental data and allows the prediction of cadmium retention in different environmental scenarios.