Group Extraction of the Rare-Earth Elements by Alkyl Phosphine Oxides of the Hexyl–Octyl Series

• Published in: Russian journal of inorganic chemistry Vol. 68; no. 4; pp. 474 - 478
• Main Authors: Tumanov, V. V., Storozhenko, P. A., Grachev, A. A., Fedin, O. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-04-2023; Springer Nature B.V
• Subjects: Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Lanthanides; Oxides; Phosphine oxide; Physical Chemistry of Solutions; Rare earth elements; Recovery; Scandium; Synthesis; Thorium; neutral extractants; nitric acid; liquid–liquid extraction; separation factors; lanthanides
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023622602902

Samples of monoalkyl and mixed-alkyl phosphine oxides of the hexyl–octyl series were synthesized previously by the Grignard method. Here, the group extraction of rare-earth metals contained simultaneously in their nitrate solutions has been studied using then-synthesized alkyl phosphine oxides. Extraction isotherms for the recovery of the total of lanthanides, scandium, and thorium from nitrate solutions have been obtained. Trihexyl phosphine oxide (THPO) exhibits the highest efficiency under these conditions. Trioctyl phosphine oxide (TOPO) exhibits the best selectivity to heavy-group lanthanides, which makes it useful for the recovery of the heavy-group lanthanide fraction. In addition, scandium and thorium were extracted completely, which in turn indicates the usefulness of phosphine oxides for their extraction. The separation factors have been determined for the entire lanthanides series.