The sorption of copper species by clays. II. Illite and montmorillonite

Abstract

The effect of changes in pH and the presence of ligands on the uptake of copper ions by an illite and a montmorillonite type clay has been investigated. The observed adsorption behaviour on montmorillonite can be interpreted in terms of an ion exchange model, i.e. all positively charged solution species compete for available sites. For illite (and kaolinite) the controlling process appears to be the formation of polymeric hydroxy species attached to particular sites on the clay. The solution pH controls the development of hydroxy bridges, and ligands influence uptake through a masking action, i.e. prevention of hydroxy species formation. Stable anionic complex ions are not adsorbed by either clay.