Analytical Sciences

Direct Temperature-Swing Extraction of Rare-Earth Elements from Acidic Solution Using the Hydrophobic Interactions of Poly(N-isopropylacrylamide) with Diglycolamide-typed Ligands

Kaname SAGA,* Hideya SUZUKI,** Tatsuro MATSUMURA,** and Takehiko TSUKAHARA*

*Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1-6 Ookayama, Meguro, Tokyo 152-8550, Japan
**Partitioning and Transmutation Technology Division, Nuclear Science and Engineering Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195, Japan

The phase transition-based gelification phenomenon of poly(N-isopropylacrylamide) [poly(NIPAAm)] has great potential in developing new waste-free extraction processes. In this study, we realized the direct and complete temperature-swing extraction of all trivalent rare-earth (RE) ions from a multi-component nitric acid solution onto a poly(NIPAAm) gel as chelate complexes with hydrophobic diglycolamide-typed ligands. Moreover, we elucidated that the extractabilities are affected by not only the coordination ability of the ligands with RE ions but also by the hydrophobic interaction between the poly(NIPAAm) and the ligands.

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