A solid-state “atomic channel” for separating rare earth elements

A cleaner route to purifying rare earth elements By: Sarah C.P. Williams UChicago PME researchers show that atomic channels can separate rare earth elements from each other—without the toxic chemicals usually used in this purification July 21, 2026 Share Share UChicago PME | A cleaner route to purifying rare earth elements on Facebook Share UChicago PME | A cleaner route to purifying rare earth elements on Twitter Share UChicago PME | A cleaner route to purifying rare earth elements on Email Share UChicago PME | A cleaner route to purifying rare earth elements on LinkedIn Former University of Chicago Pritzker School of Molecular Engineering PhD student Siqi Zou (left) and Assoc.

Prof. Chong Liu led a team of reseachers from UChicago PME and Northwestern University that developed a cleaner method to separate rare earth elements from each other, which could affect technology manufacturing. (Photo by John Zich) Rare earth elements like lanthanum, neodymium, and dysprosium are used to build the electric motor in your car, the LED lights in your house, and the MRI machine at your doctor’s office.

But first, they have to be mined and separated from each other. Historically, that purification has been a difficult, costly, process, relying on huge amounts of toxic chemicals.Now, researchers in the lab of Assoc.

Prof. Chong Liu at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME), working with colleagues at Northwestern University and Argonne National Lab, have discovered a cleaner method to separate rare earth elements from each other.The new approach relies on a layered form of manganese oxide—a mineral material with the right size layers to allow ions to slip in and out and to differentiate rare earth elements.

“This is the first time that people have used electrochemical intercalation and harnessed the structural characteristics to separate similar lanthanides, which are intrinsically very hard to separate,” said Liu, senior author of the new study, which published in Nature Chemical Engineering. “What’s also valuable is that we provided a lot of new understanding of how rare earth ions are interacting with this material and how we can manipulate it to better selectivity.”“This kind of separation is competitive with other rare earth separation methods, but it’s done in water, without organic solvents,” said George Schatz, professor of chemistry at Northwestern University and a co-author of the study.

“That’s a difference that could actually matter at manufacturing scale.”This is the first time that people have used electrochemical intercalation and harnessed the structural characteristics to separate similar lanthanides, which are intrinsically very hard to separate.Assoc.

Prof. Chong Liu, senior author of the studySqueezing elements through channelsThe 17 rare earth elements—including the 15 lanthanides, plus scandium and yttrium—rarely occur alone. They’re almost always mined together and chemically they’re nearly identical, with only tiny differences in ion size and acidity differentiating each one.

Pulling them apart typically requires custom-built molecules and large amounts of acid, which is used to strip each element off those molecules. “Rare earths always come mixed together, whether they’re in an ore or in a waste stream, and separating them from each other is a second, very challenging step even after you’ve pulled them away from everything else,” said UChicago PME graduate student Jiadong Liu, a co-first author of the new paper. Chong Liu and her colleagues knew that one of the differences between rare earth ions was the size of the water shell surrounding each one when they are dissolved in solution.

Lighter rare earths like lanthanum have larger first water shell, while heavier rare earths like dysprosium have a smaller first shell. Taking advantage of that size difference, Chong Liu’s group engineered manganese oxide so that the gaps between its stacked layers were only a few water molecules wide. Then, they squeezed raw mixtures of rare earth elements inside.

The approach divided the elements into two groups. Heavier lanthanides with smaller water shells stuck in the channels more tightly. Lighter lanthanides with larger shells pushed the layers apart, loosening their grip.

To confirm what was happening at a molecular level, the UChicago PME team collaborated with Schatz’s group at Northwestern to run quantum mechanical simulations using a method called density functional theory, which predicts how atoms arrange themselves and interact based on the underlying physics. They also worked with Argonne scientists to obtain experimental X-ray data. “It was incredibly rewarding to see how closely our density functional theory calculations matched the synchrotron X-ray measurements,” said co-first author Woo Cheol Jeon, who conducted the research as a postdoctoral researcher in George Schatz’s lab at Northwestern.

“The calculations let us see, atom by atom, how each rare ea