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.