Separation of the Lanthanons at Amalgam Cathodes. IV. High Purity Ytterbium from Mixtures of Heavy Lanthanons by Aqueous Electrolysis1

Abstract

Ytterbium was separated from a mixture of heavy lanthanons by electrolysis into mercury from an aqueous lithium citrate electrolyte at pH 6. Enrichment of the Yb/sub 2/O/sub 3/ was from 31% to>99.9% purity and the yield was quantitative. A 50-50 mixture of ytterbium and radioactively tagged thulium was used to study the effect of pH on electrolysis rates and on the purity of electrolyzed ytterbium. A strong pH dependence was found with the rate of electrolysis of ytterbium being 40-fold slower at pH 11 than at pH 6. The average purity of ytterbium electrolyzed from the 50-50 mixture of Yb-Tm was 99.98% at pH 6 and 99.96% at pH 8. A foreign impurity effect was found (believed to be platinum contamination) which affected the rate of electrolysis of thulium, and for one experiment the rate for ytterbium was also affected. Since the effect was different for thulium and ytterbium the purity of the electrolyzed ytterbium was variant. (auth)