KU Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee, Belgium.
Dalton Trans. 2014 Feb 28;43(8):3186-95. doi: 10.1039/c3dt52541d.
The solvent extraction of trivalent rare-earth ions and their separation from divalent transition metal ions using molten salt hydrates as the feed phase and an undiluted fluorine-free ionic liquid as the extracting phase were investigated in detail. The extractant was tricaprylmethylammonium nitrate, [A336][NO3], and the hydrated melt was calcium nitrate tetrahydrate, Ca(NO3)2·4H2O. The extraction behavior of rare-earth ions was studied for solutions of individual elements, as well as for mixtures of rare earths in the hydrated melt. The influence of different extraction parameters was investigated: the initial metal loading in the feed phase, percentage of water in the feed solution, equilibration time, and the type of hydrated melt. The extraction of rare earths from Ca(NO3)2·4H2O was compared with extraction from CaCl2·4H2O by [A336][Cl] (Aliquat 336). The nitrate system was found to be the better one. The extraction and separation of rare earths from the transition metals nickel, cobalt and zinc were also investigated. Remarkably high separation factors of rare-earth ions over transition metal ions were observed for extraction from Ca(NO3)2·4H2O by the [A336][NO3] extracting phase. Furthermore, rare-earth ions could be separated efficiently from transition metal ions, even in melts with very high concentrations of transition metal ions. Rare-earth oxides could be directly dissolved in the Ca(NO3)2·4H2O phase in the presence of small amounts of Al(NO3)3·9H2O or concentrated nitric acid. The efficiency of extraction after dissolving the rare-earth oxides in the hydrated nitrate melt was identical to extraction from solutions with rare-earth nitrates dissolved in the molten phase. The stripping of the rare-earth ions from the loaded ionic liquid phase and the reuse of the recycled ionic liquid were also investigated in detail.
详细研究了使用熔融盐水合物作为进料相和未稀释的无氟离子液体作为萃取相，从二价过渡金属离子中萃取和分离三价稀土离子。萃取剂为三辛基甲基氯化铵硝酸盐，[A336][NO3]，水合熔融盐为四水硝酸钙，Ca(NO3)2·4H2O。研究了单一元素溶液以及水合熔融盐中稀土元素混合物中稀土离子的萃取行为。考察了不同萃取参数的影响：进料相中初始金属负载量、进料溶液中水的百分比、平衡时间和水合熔融盐的类型。将从 Ca(NO3)2·4H2O 中萃取稀土与从 CaCl2·4H2O 中用[A336][Cl]（Aliquat 336）萃取进行了比较。发现硝酸盐体系更好。还研究了从过渡金属镍、钴和锌中萃取和分离稀土。从 Ca(NO3)2·4H2O 中用[A336][NO3]萃取剂萃取时，观察到稀土离子对过渡金属离子的分离系数非常高。此外，即使在过渡金属离子浓度非常高的熔融盐中，也可以有效地从过渡金属离子中分离出稀土离子。在少量 Al(NO3)3·9H2O 或浓硝酸存在下，稀土氧化物可以直接溶解在 Ca(NO3)2·4H2O 相中。在水合硝酸盐熔体中溶解稀土氧化物后萃取的效率与从溶解在熔融相中的稀土硝酸盐溶液中萃取的效率相同。还详细研究了从负载离子液体相中洗脱稀土离子和再循环使用回收离子液体的情况。
