Adsorption of light lanthanides on the zeolite A surface

Adsorption studies of light lanthanides on the powdered zeolite type A are presented. It results from the mathematical description of the adsorption isotherms and from complementary scanning electron microscopy (SEM) studies of the adsorbent surface, that heterogeneity of the A type zeolite is most pronounced in the case of lanthanum and cerium, which fact correlates very well with the ability of these lanthanides to hydroxide complexes formation. It was found from the observation of the distribution constants Kd of lanthanides on pH values of the aqueous phase, that lanthanide adsorption proceeds through ion-exchange pathway up to pH 4.9, 4.8, 5.2, 4.0, 4.5 for La, Ce, Pr, Nd and Sm, respectively. For higher pH values surface hydrolysis with evolution of LnpZe3p(OH)q−q seems to be dominant component in the overall adsorption process. The separation of Nd from La, Ce and Pr via adsorption process is recommended.