RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

A comparison was made between the adsorptive behaviors of Cd²⁺ and UO₂²⁺ relative to two smectites that differed in their ratio of edge sites to fixed-charge sites. Adsorption varied with both pH and ionic strength, consistent with sorptive contributions of ion exchange and coordination reactions to edge hydroxyls. Both clay minerals exhibited a greater affinity for UO₂²⁺ than for Cd²⁺, and the clay with a higher proportion of edge sites retained both ions more strongly. A computational model including fixed-charge sites and edge hydroxyls resulted in a good prediction of overall UO₂²⁺ and Cd²⁺ uptake to both smectites.