Solvent extraction of europium(III) from nitrate medium with 4-acyl-isoxazol-5-ones and 4-acyl-5-hydroxy-pyrazoles. Effect of salts and diluents

• Published in: Hydrometallurgy Vol. 82; no. 1; pp. 100 - 109
• Main Authors: Arichi, Jaouad, Goetz-Grandmont, Geneviève, Brunette, Jean Pierre
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2006; Elsevier
• Subjects: Acyl-hydroxyl pyrazoles; Acyl-isoxazolones; Applied sciences; Diluent effects; Europium; Exact sciences and technology; Metals. Metallurgy; Nitrate complex; Production of metals; Solvent extraction; β-diketone; Nitrate complex; HPtbBI; HNPPLP; β-diketone; Diluent effects; Solvent extraction; HPBI; HPMBP; HPMTFP; HPMtbBP; Acyl-isoxazolones; HTTA; Europium; Acyl-hydroxyl pyrazoles; Lanthanide; p-diketone; Solvent; Hydrometallurgy
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2006.04.004

The solvent extraction of europium(III) from nitrate medium (0.1 M or 1 M) with acidic chelating extractants HL in chloroform, at 25 °C, has been studied. The extractants are either 3-phenyl-4-acylisoxazol-5-ones (acyl = benzoyl, “HPBI”, and p-tert-butylbenzoyl, “HPtbBI”), or substituted 4-acyl-5-hydroxypyrazoles 1-( p-nitro-phenyl)-3-phenyl-4-lauroyl-5-hydroxypyrazole, “HNPPLP”, and 1-phenyl-3-methyl-4-( p-tert-butylbenzoyl)-5-hydroxy-pyrazole, “HPMtbBP”, of various acidities. In all cases europium is extracted by cation exchange as EuL 3,org. Because of their higher acidity, extractions performed with 4-acylisoxazol-5-ones occur at lower pH range than with 4-acylpyrazol-5-ones. The order of extraction efficiency is: HPMtbBP (p K a = 4.1) < HNPPLP (p K a = 3.2) < HPtbBI (p K a = 1.3) < HPBI (p K a = 1.2). The nature of the cation of the inorganic salt used to fix the ionic strength has no effect on the extraction. Due to the competitive complexation of Eu 3+ by NO 3 − in the aqueous phase, the extraction from nitrate medium is less efficient than from perchlorate medium: the order of extraction is NaNO 3 ≈ KNO 3 ≈ LiNO 3 < NaClO 4. Extraction was also studied in other diluents and increased in the order: chloroform < 1,2-dichloroethane ≤ benzene ≈ toluene ≈ hexane. The same order was observed for europium extraction with several other β-diketones. On the basis of values found in literature, trends of extraction of europium with β-diketones in several diluents are proposed.