Sorption of Tetravalent Plutonium onto Kaolinite in the Presence of Humic Substances

Humic substances (HS), a mixture of organic macromolecules, are distributed ubiquitously in the ecosphereand play an important role in the interaction processes with actinideions and clay minerals. The ternary system plutoniumkaolinite-humic substance is studied here in order to understand and predict the speciation and migration behavior of plutonium in a geogenic aquatic system. The influence of HS on the sorption of Pu(IV) onto kaolinitewas investigated as a function of pH, contact time, concentration of HS, and adding sequences of the reactants. The sorption studies were performed by batch experiments under aerobic conditions. A pH range of 1-9 was studied with Pu(IV) concentrations of 7.1×10 -8 M, 0-100 mg/L of HS, and a solid