An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Sustainable Chemistry

Background:

• Rare-earth metals are essential for modern electronics and magnets.
• Consumer waste presents a viable source for rare-earth metal recovery.
• Efficient separation techniques are crucial for incentivizing rare-earth recycling.

Purpose of the Study:

• To develop a simple method for targeted separation of rare-earth metal salts.
• To investigate the use of a tripodal nitroxide ligand for selective rare-earth metal complexation and separation.
• To demonstrate the separation of neodymium (Nd) and dysprosium (Dy) using the developed method.

Main Methods:

• Synthesis and characterization of a tripodal nitroxide ligand (TriNOx).
• Investigation of the self-associative equilibrium of metal-TriNOx complexes in solution.
• Utilizing differences in equilibrium constants (Keq) for selective leaching and separation of rare-earth metals.

Main Results:

• The tripodal nitroxide ligand forms metal complexes with a size-sensitive aperture.
• Metal cation exposure induces a self-associative equilibrium dependent on the metal.
• Effective separation of neodymium from dysprosium was achieved with a separation ratio (SNd/Dy) of 359.

Conclusions:

• The TriNOx ligand facilitates size-selective complexation of rare-earth metals.
• Differences in metal-ligand complex equilibria allow for targeted separations.
• This method offers a promising approach for the recovery of valuable rare-earth elements from mixed sources.