Thin-layer chromatography of rare earth elements in carboxymethyl cellulose-aqueous sodium chloride systems and the specific separation of yttrium

Abstract

The thin-layer chromatographic behavior of all rare earths, except for promethium on carboxymethyl cellulose in aqueous sodium chloride solutions, has been surveyed as a function of the concentration of the salt to develop a new system for the separation of rare earths. It is reasonable to suppose that the competitive cation exchange between the solvent cations and the rare earths, the surface complexation of the rare earths with the carboxymethyl groups, and the salting-out effect of the solvent used, and moreover a change in the inner sphere coordination numbers across the rare earth series, play important roles in determining the Rf values of the metals in the present system. Yttrium, which generally belongs to heavier rare earths, has been separated from all of the rare earths, except for lanthanum, which provides Rf values similar to those of yttrium.