Extraction of Yttrium from Carbonate Media Using Mixtures of Aromatic Dihydroxy Compounds and Methyltrioctylammonium Carbonate

The solvent extraction of the 90 Y/ 90 Sr pair from carbonate media with mixtures of aromatic dihydroxy compounds and a quaternary ammonium salt—methyltrioctylammonium carbonate (MTOAC)—in toluene and butyl acetate was studied. It was found that MTOAC increases the distribution coefficients of both the extractant itself and its solvate with yttrium due to the formation of a mixed complex of yttrium and a dihydroxyaromatic ligand with MTOAC. During extraction from alkaline carbonate media in the pH range of 12–13.5 with mixtures of 0.01 M 2,3-dihydroxynaphthalene and 0.015 M MTOAC in butyl acetate or toluene, the distribution coefficients of yttrium exceed 80; the separation factors of the 90 Y/ 90 Sr pair under these conditions are more than 10 5 . Dilute solutions of hydrochloric, nitric, and sulfuric acids can be used for the complete stripping of yttrium. The studied mixtures are chemically stable and do not change the extraction properties upon multiple extraction/stripping cycles. Model experiments on the leaching of yttrium from natural samples showed that the percentage of stable yttrium extraction from sand is 70–80%, while the percentage of yttrium extraction from soil is 50–60%.