Sorption characteristics of237Np,238Pu and241Am in sedimentary materials

Adsorption experiments were performed to measure distribution coefficients of²³⁷Np(V),²³⁸Pu(IV) and²⁴¹Am(III) for sedimentary sequential chemical extraction of the adsorbed radionuclides was carried out with water, CaCl₂, KCl, NH₂OH−HCl, K-oxalate and H₂O₂ solutions, to elucidate their dominant sorption mechanisms. The distribution coefficient of²³⁷Np was two orders of magnitude smaller than that of²³⁸Pu and²⁴¹Am. Most of²³⁷Np adsorbed was extracted with CaCl₂ solution and its sorption was controlled by a reversible ion exchange reaction. The adsorbed²³⁸Pu was mainly extracted with NH₂OH−HCl+K-oxalate solution and its sorption was possibly controlled by irreversible reactions.