Ionic Liquid-Based Recovery of Rare Earth Elements

The recovery of rare earth elements using ionic liquids has emerged as a sustainable alternative to conventional hydrometallurgical processes. Ionic liquids are salts that remain liquid at moderate temperatures, combining negligible vapour pressure with highly tunable solvation properties. By selecting appropriate cation–anion combinations and incorporating functional groups, these media can distinguish lanthanides by ionic radius, coordination preferences and complexation strength. Recent advances have integrated leaching, separation and metal recovery into single-phase or biphasic systems, achieving high selectivity and purity while reducing energy consumption and secondary waste. Such strategies hold promise for diversifying supply sources—from end-of-life magnets and electronic waste to mine tailings and industrial effluents—thereby closing material cycles and mitigating environmental impact as global demand for rare earths continues to grow.

Research from Nature Portfolio

Recent studies have combined biomolecular recognition and advanced framework design within ionic liquid environments to set new benchmarks in separation efficiency. A metal-sensitive lanmodulin dimer, operating in an ionic liquid medium, exploits sub-angstrom differences in ionic radii to achieve single-stage separation of neodymium and dysprosium with purities exceeding 98 per cent. Separately, interpenetrated metal-organic frameworks featuring dense carboxyl and triazole functionalities dispersed in ionic liquid have demonstrated separation factors of up to 796 for praseodymium/ytterbium and 273 for neodymium/erbium in a single step. These breakthroughs illustrate the power of marrying biological or framework selectivity with the inherent modularity of ionic liquids for sustainable rare earth recovery.

Ionic Liquid-Based Recovery of Rare Earth Elements publication trend

The graph below shows the total number of articles in ionic liquid-based recovery of rare earth elements across all publications each year (not limited to Nature Index journals).

Technical terms

Ionic liquid: A salt that is liquid below 100 °C, composed of organic cations and various anions, valued for negligible vapour pressure and adjustable solvation properties.

Lanmodulin: A natural protein with exceptionally high affinity and selectivity for lanthanide ions, whose metal-induced oligomerisation can be harnessed for separation.

Thermomorphic system: A solvent mixture that undergoes reversible phase separation upon temperature change, enabling integrated leaching and extraction in one medium.

Metal-organic framework (MOF): A porous crystalline network of metal nodes linked by organic ligands, offering high surface area and functional sites for selective adsorption and separation.

References

1. Enhanced rare-earth separation with a metal-sensitive lanmodulin dimer. Nature (2023).
2. Rationally designed nanotrap structures for efficient separation of rare earth elements over a single step. Nature Communications (2024).
3. Recycling of rare earths from NdFeB magnets using a combined leaching/extraction system based on the acidity and thermomorphism of the ionic liquid [Hbet][Tf 2 N]. Green Chemistry (2015).
4. Rare-earth recycling using a functionalized ionic liquid for the selective dissolution and revalorization of Y 2 O 3 :Eu 3+ from lamp phosphor waste. Green Chemistry (2015).