Advanced liquid–liquid extraction systems for the separation of rare earth ions by combination of conversion of the metal species with chemical reaction
Advanced liquid–liquid extraction systems for the separation of rare earth ions by combination of conversion of the metal species with chemical reaction
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DOI：
10.1016/s0022-4596(02)00198-6
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发表时间：
2003-02
影响因子：
3.3
通讯作者：
S. Nishihama;T. Hirai;I. Komasawa
中科院分区：
文献类型：
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作者：
S. Nishihama;T. Hirai;I. Komasawa
研究了先进的液-液萃取与化学反应相结合的金属组分转化。重点介绍了水溶性络合剂的络合反应和金属离子的光化学氧化还原反应。在络合生成反应的情况下，在萃取体系的水相中加入乙二胺四乙酸（EDTA）。由于金属与EDTA之间络合物形成能力的差异，使得相邻稀土金属的分离得到改善。在萃取平衡的基础上，模拟研究了逆流混合器-沉降器级联分离金属的工艺设计，确定了萃取剂的高负荷，并建立了物料平衡方程。在光化学氧化还原反应中，进行了Sm/Eu/Gd混合物中Eu的光还原溶出和La/Ce/Pr混合物中Ce的光氧化萃取。当目标金属的价态发生变化时，其可萃取性发生显著变化，从而实现有效的分离。
Advanced liquid–liquid extraction combined with the conversion of the metal species with chemical reactions has been investigated. The complex formation reaction with water-soluble complexing reagent and the photochemical redox reaction for metal ions are focused. In the case of complex formation reaction, ethylenediaminetetraacetic acid (EDTA) was added to the aqueous phase of the extraction system. The separation of adjacent rare earth metals improves, due to the difference of the complex formation ability between metals and EDTA. The design of separation process of the metals with countercurrent mixer-settler cascade was also investigated with simulation based on the extraction equilibrium, determined up to high loadings of the extractant, and the material balance equations. In the case of photochemical redox reaction, the photoreductive stripping of Eu from Sm/Eu/Gd mixture and the photooxidative extraction of Ce from La/Ce/Pr mixture were carried out. The extractability of the target metals changes dramatically when their valences are changed, and then the effective separation can be achieved.