Analytical separation of scandium (III) from yttrium (III) and lanthanum (III) by tributyl phosphine oxide (TBPO)

Abstract

Abstract A systematic study of solvent extraction behaviour of trivalent scandium, yttrium and lanthanum with tributyl phosphine oxide from salicylate media is carried out, and a scheme for separation for scandium–yttrium and scandium–lanthanum is discussed. Scandium (III) is quantitatively extracted from 1.25×10 −2 –1.88×10 −2 M sodium salicylate at pH 3.8–4.2 with 2.3×10 −3 M TBPO dissolved in toluene, Yttrium is quantitatively extracted at pH 4.5–6.0 from 1.25×10 −2 –5×10 −2 M sodium salicylate with 2.3×10 −3 M TBPO dissolved in toluene while lanthanum is extracted at pH 4.8–8.0 from 2.5×10 −2 –6.25×10 −2 M sodium salicylate with 4.58×10 −3 M TBPO dissolved in toluene. A possible mechanism for the extraction is proposed. The extracted metal ions were separated by selective stripping and estimated spectrophotometrically following a complexation with PAR and Thoron I. The proposed method facilitates the separation and determination of scandium, yttrium and lanthanum from binary and synthetic mixtures.