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

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• 作者：Jaouad Arichi ; Geneviè ; ve Goetz-Grandmont and Jean Pierre Brunette
• 关键词：Solvent extraction ; Europium ; Nitrate complex ; &#x3b2 ; -diketone ; Acyl-isoxazolones ; Acyl-hydroxyl pyrazoles ; Diluent effects
• 刊名：Hydrometallurgy
• 出版年：2006
• 出版时间：July 2006
• 年：2006
• 卷：82
• 期：1-2
• 页码：100-109
• 全文大小：185 K

文摘

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 (pK_a = 4.1) < HNPPLP (pK_a = 3.2) < HPtbBI (pK_a = 1.3) < HPBI (pK_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 Eu³⁺ by NO₃⁻ in the aqueous phase, the extraction from nitrate medium is less efficient than from perchlorate medium: the order of extraction is NaNO₃ "48; KNO₃ "48; LiNO₃ < NaClO₄. Extraction was also studied in other diluents and increased in the order: chloroform < 1,2-dichloroethane Ȧ4; benzene "48; toluene "48; hexane. The same order was observed for europium extraction with several other &#x3b2;-diketones. On the basis of values found in literature, trends of extraction of europium with &#x3b2;-diketones in several diluents are proposed.