Selective Eu(III) Electro‐Reduction and Subsequent Separation of Eu(II) from Rare Earths(III) via HDEHP Impregnated Resin

Abstract

Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in 0.01 mol · dm⁻³ hydrochloric acid medium. Eu(III) reduction took place after all the dissolved oxygen was reduced and then proceeded steadily. Separation of Eu(II) from trivalent rare earths (La, Ce, Sm, Gd, Er, Yb) was carried out using a novel impregnated resin based on bis(2‐ethylhexy1)phosphoric acid. Eu(II) showed much lower affinity towards the resin than the trivalent rare earths and broke through the column readily. Eu of purity higher than 99.8% was yielded. The back‐oxidation of Eu(II) was observed during the sorption and Eu(III) was absorbed onto the resin. Adsorbed light and middle rare earths could be stripped from the loaded resin by 3M hydrochloric acid. Stripping of heavy rare earths (Er, Yb) was problematic.

Keywords:

• Eu
• solvent impregnated resin
• rare earths
• separation

Acknowledgement

This work was financially supported by the Japan Society for the Promotion of Science (JSPS).