Separation of Electrochemically Generated Ce(IV) from Rare Earths(III) in Nitric Acid Media by TBP Impregnated Resin

Abstract

Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials with high oxygen evolution overpotential was carried out. Ce(IV) nitrato complexes were adsorbed on a novel resin, based on porous silica beads with immobilized polystyrene/DVB copolymer, that was impregnated with tri‐n‐butyl phosphate (TBP). Under the studied conditions, Ce(IV) sorption increased with increasing nitric acid concentration (0.5–6 mol · dm⁻³). Oxidation of sorbent by adsorbed Ce(IV) species resulting in Ce(III) release to the solution was observed and thoroughly evaluated. In spite of problems with TBP leakage (12%), column separation of pure Ce(IV) from Y(III) and La(III) was achieved in 6 mol · dm⁻³ HNO₃ at 288 K. Ce(IV) breakthrough capacity was 0.48 mol · kg⁻¹‐TBP. Column regeneration with 0.1 mol · dm⁻³ nitric acid yielded Ce solution with purity higher than 99.99 wt.% with respect to La and Y impurities.

Keywords:

• Cerium
• electro‐oxidation
• separation
• lanthanides
• TBP impregnated resin

Acknowledgements

This work was financially supported by the Japan Society for the Promotion of Science (JSPS). The authors would like to thank Dr. Y. Hirose for his valuable suggestions and comments on the electrolysis work.