3.2. Characteristics of clay fractions
The cation exchange capacity (CEC) is an important characteristic of clays. It represents the overall quantity of charges
available on the exchanger material. It is related to the surface density of charges through the specific surface area. The relative concentrations of the cations help determine the degree of adsorption. The method used for determining CEC, which involves the complete exchange of the naturally-occurring cations by ammonium, is the standard method for CEC
determination.
Table 2 shows the values of CEC for the different clayminerals.