Publication Date： October 22, 2025
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Metal Extraction Technology Evolving with the Power of Fluorine
－Contributing to a Sustainable Society Through the Development of New Extraction Methods That Combine Efficiency and Safety－
Fig. 1 Third-phase formation behavior and nanoscale structure of (a) a non-fluorinated extractant, and (b) a fluorinated extractant
For the fluorinated extractant, the oil phase appears as the lower layer due to its higher density.
Resource recycling is important for a sustainable society. Among the various methods available, solvent extraction, which can separate useful metal resources, is attracting attention. However, the concentrated phase of metal ions (third phase) often formed during high-concentration metal extraction has been a long-standing issue because it reduces the safety of the process.
In this study, we focused on the strong hydrophobicity of fluorine and developed an extraction system that suppresses third-phase formation, and we elucidated its microstructure using the small-angle neutron scattering (SANS) device SANS-J installed in the research reactor JRR-3. Normally, in conventional extraction systems employing non-fluorinated extractants, the extraction of high concentrations of zirconium (Zr) ions leads to the aggregation of approximately 350 molecules in the organic phase, forming large molecular assemblies that eventually result in third phase formation (Fig. 1a). In contrast, when using the newly developed fluorinated extractant, the extraction of high concentrations of Zr ions produces small molecular aggregates consisting of about 14 molecules in the oil phase. These aggregates repel each other due to the hydrophobicity of fluorine, thereby maintaining their size and preventing third phase formation (Fig. 1b).
This achievement has provided a concrete solution to the third phase formation, for which there had been no fundamental solution until now. The fluorinated extractants developed in this study has great potential for advancing metal ion separation technology, and is expected to contribute to solving resource issues in Japan.
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