Kinetics of plutonium and americium sorption to natural clay.

Kinetics of Pu(IV) and Am(III) sorption from natural groundwater to three types of clays were studied at trace concentrations of the elements. Higher K(d) values were determined for sorption of Pu than of Am, and no clear dependence of the K(d) values and the kinetic coefficients on the composition of the clays can be deduced. Kinetic data evaluated by models for six different control processes indicated a sorption mechanism controlled by Pu or Am diffusion in the inert layer on the surface of the clays.