Adsorption Behaviors of f-Elements on Quaternary Pyridinium Resin

We have been studied the separation of trivalent actinides and lanthanides by using tertiary pyridine resin. The adsorption behaviors of actinides and lanthanides on the tertiary pyridine resin in the hydrochloric acid system and the nitric acid system are completely different; namely, actinides are strongly adsorbed compared to lanthanides in the hydrochloric acid system, while in the nitric acid system, the adsorption strength depends on only their ionic radii. For the clarification of the adsorption mechanism, the chromatography experiments using the tertiary pyridine resin and the quaternary pyridinium resin were carried out. From a comparison of the adsorption behaviors on these two types of resins, it was concluded that the adsorption mechanism in the hydrochloric acid system is attributable to the coordination with the pyridine group, while in the nitric acid system, the f-elements are adsorbed on the tertiary pyridine resin by the mechanism of the anion exchange adsorption.