Lucy Muruchi, Jonas Van Olmen, Humberto Estay, Daniela Millán, and Tom Van Gerven of the Department of Chemical Engineering at KU Leuven and the Advanced Mining Technology Center (AMTC) at Universidad de Chile have published a new article entitled: “Usage of inorganic polyoxometalates of tungsten for extraction of rare earths in an aqueous two-phase system (ATPS): Preliminary results.” The article was published in Hydrometallurgy on 23 May 2025.
Rare earth elements (REEs) are critical for modern technologies, yet their extraction remains environmentally challenging. This study explores a novel, greener approach using polyoxometalates (POMs)—inorganic metal-oxygen clusters—as extractants in aqueous two-phase systems (ATPS) composed of PEG and MgSO₄. The research investigates how the structure and concentration of POMs, particularly their number of vacant sites (lacunarity), influence the selective extraction of REEs.
Key findings include:
- SiW₉, the most lacunary POM tested, showed the strongest competitive extraction effect, especially for heavy REEs like Yb and Er.
- Acidity and REE composition in the feed solution significantly affect extraction efficiency and selectivity.
- Stripping of REEs from the light phase was achieved using tetraethylammonium chloride, with selectivity toward light REEs under alkaline conditions.
- Continuous flow experiments using microreactors successfully replicated batch extraction performance, demonstrating the feasibility of scaling up this green extraction method.
This work not only advances the understanding of REE-POM interactions in ATPS but also opens new avenues for sustainable and scalable REE recovery using microfluidic technologies.
Reference
Lucy Muruchi, Jonas Van Olmen, Humberto Estay, Daniela Millán, Tom Van Gerven,
Usage of inorganic polyoxometalates of tungsten for extraction of rare earths in an aqueous two-phase system (ATPS): Preliminary results, Hydrometallurgy, Volume 236, 2025, 106507, https://doi.org/10.1016/j.hydromet.2025.106507
Acknowledgements
This research was supported by ANID-Chile through the POSTDOCTORADO FONDECYT Project No. 3200341 and the AMTC Basal Fund AFB230001. JVO and TVG acknowledge funding from the Research Foundation – Flanders (FWO), project G0D7421N.
