Analytical Sciences

Separation of Light and Middle Lanthanides Using Multistage Extraction with Diglycolamide Extractant

Takafumi MATSUTANI,*,** Yuji SASAKI,* and Shoichi KATSUTA***

*Nuclear Science and Engineer Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
**Department of Chemistry, Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
***Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan

We investigated the chemical behavior of lanthanides (Ln) by multistage extraction. Using 10 aqueous phases with Ln and 3 organic phases, we drew the breakthrough curves for light and middle Ln. Our study reveals that the limit of metal extraction depends on their D values and the metal concentration employed in experiments. From the multistage extractions of 15 stage aqueous phases and 15 stage organic phases, three curves (extraction curves, back-extraction curves, and separation curves) were obtained. Setting appropriate conditions, adequate separation of light Ln from middle ones can be achieved. As an example, under the condition of the separation curve experiment (aqueous phase: 0.5 M HNO₃, organic phase: 0.1 M TDDGA (N,N,N′,N′-tetradecyl-diglycolamide) in n-dodecane), the recovery of more than 99% of Sm in the organic phase with less than 1% of Nd can be obtained, even in the case of two metals adjacent to each other in the Ln series.

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