Magnetic Field Directed Rare‐Earth Separations

Abstract

The separation of rare‐earth ions from one another is challenging due to their chemical and physical similarities. Nearly all rare‐earth separations rely upon small changes in ionic radii to direct speciation or reactivity. Herein, we show that the intrinsic magnetic properties of the rare‐earth ions impact the separations of light/heavy and selected heavy/heavy binary mixtures. Using TriNOx3− ([{(2‐tBuNO)C6H4CH2}3N]3−) rare‐earth complexes, we efficiently and selectively crystallized heavy rare earths (Tb–Yb) from a mixture with light rare earths (La and Nd) in the presence of an external Fe14Nd2B magnet, concomitant with the introduction of a concentration gradient (decrease in temperature). The optimal separation was observed for an equimolar mixture of La:Dy, which gave an enrichment factor of EFLa:Dy=297±31 for the solid fraction, compared to EFLa:Dy=159±22 in the absence of the field, and achieving a 99.7 % pure Dy sample in one step. These results indicate that the application of a magnetic field can improve performance in a molecular separation system for paramagnetic rare‐earth cations.

The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone

“…With a modification of the ligand, using long alkyl chains, the group was able to perform a liquid‐liquid extraction of late REE, while the early ones remained in the aqueous phase . Recently, also magnetic field driven REE separations have been reported . Among the REE, the early lanthanides (La–Eu) are now recognized as biorelevant for methylotrophic bacteria habituating a number of different ecosystems (plant phyllospheres, volcanic mudpots, soil and aquatic environments) .…”

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

“…Considering these values, a magnetic separation of ions could be deemed an Icarian endeavor. Nevertheless, attempts of rare earth ion separation in a magnetically modified Clusius-Dickel thermal diffusion column , were reported by Ida and Walter Noddack in the 1950s. − After a 50 year hiatus, interest in the effects of magnetic field gradients on ionic solutions has been revived. ,,− Magneto-convection only arises when the magnetic field gradient force is rotational, which necessitates a susceptibility gradient and magnetic field gradient that are non-parallel . Interferometric measurements generated evidence of magnetic ion enrichment around the surface of an evaporating solution containing a single paramagnetic species. − The inhomogeneity in these systems is caused by the input of thermal energy, which is the driving force for the concentration change and essentially a distillation process.…”

Neutron Imaging of Paramagnetic Ions: Electrosorption by Carbon Aerogels and Macroscopic Magnetic Forces

“…Nevertheless, attempts of rare earth ion separation in an inhomogeneous magnetic field were reported by Ida and Walter Noddack in the 1950s [7][8][9]. After a 50 year hiatus, interest in the effects of magnetic field gradients on ionic solutions has been revived [5,6,[10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Magneto-convection only arises when the magnetic field gradient force is rotational, which necessitates a susceptibility gradient and magnetic field gradient that are orthogonal to each other [24].…”