Influence of Exchangeable Cation on the Sorption of Trace Amounts of Cadmium by Montmorillonite

Abstract

Abstract The effect of different exchangeable cations on the sorption of trace amounts of Cd by montmorillonite (clay fraction, Upton, Wyoming) was studied by equilibrating samples of homoionic clay suspensions with CdCl 2 solutions ranging from 15 to 120 µg Cd/liter. These Cd concentrations are similar to those found in natural and contaminated soil‐water systems. The amount of Cd sorbed on the montmorillonite surfaces depended on the kind of exchangeable cation, decreasing in the order Na‐montmorillonite > K‐montmorillonite > Ca‐montmorillonite > Al‐montmorillonite. Exchangeable Al was found to be particularly effective in reducing Cd sorption by high energy sites on montmorillonite.