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Most people have never heard of neodymium, a strong, silvery rare-earth metal, yet almost all of us carry around a little bit of it in our pocket every day.

“Your cell phone, your computer — all of these things run on lanthanides, a series of 14 elements that are relatively heavy metals,” Institute of Arctic and Alpine Research (INSTAAR) geochemist and CU professor��Tom Marchitto said.

Though these elements are rare, they are found in unusually high concentrations in certain streams here in Colorado. The phenomenon occurs along Colorado’s “mineral belt,” where acidic waterways pick up metals trapped in bedrock. With Marchitto’s help, INSTAAR biogeochemist and CU distinguished professor��Diane Mcknight and collaborators have spent the past decade investigating this process at old mining sites and natural “acid rock” deposits around the state.

Now, their efforts could lead to another exciting discovery. McKnight and Marchitto are part of��, funded by the U.S. Department of Energy and led by the University of Missouri, that seeks a method for extracting rare earths from acid rock drainage for industrial uses.

The project comes at a fortuitous moment. Recently, the Trump administration��. At the same time, metal contamination from acid rock drainage is increasing in Colorado and��. If the new project is successful, it could improve water quality by removing metal while simultaneously producing essential raw materials for personal electronics, electric vehicles and military technologies.

“Improving water quality impacts associated with acid mine and rock drainage is really expensive,” McKnight said. “If there’s a valuable commodity that could be recovered through that process, it could change the equation.”

Master's students Athena Bolin and Adam Odorisio collect water samples from a creek near Aspen. (courtesy photo)

An unexpected finding

91���Ѽ a decade ago, rare earth metals weren’t yet on Diane McKnight’s radar. For years, she and her students had characterized processes leading to metals like copper and zinc leaching into waterways along Colorado’s mineral belt. But, a serendipitous accident that led to a further discovery.

“A colleague happened to put my student, Garrett Rue’s, samples at the end of a run testing for rare earths,” McKnight said. “Afterward, he got in touch with Garrett and asked, “where are these samples from? There’s 200 micrograms per liter of neodymium!”

Later, Rue��. In the years since, a steady stream of passionate students have scrounged funding to continue investigating the presence of rare earths in mountain watersheds. Marchitto has supported these efforts through��his lab’s powerful mass spectrometer, capable of measuring trace amounts of metals in water samples.

is that metal concentrations in Colorado are increasing over time as warming summer temperatures thaw previously frozen sites containing acid-forming bedrock. This result is alarming from an ecological perspective. If metal concentrations climb too high, they can kill aquatic species,��.��

But, these increased concentrations may also present an opportunity. That’s according to Baolin Deng and Pan Ni, two distinguished researchers at the��, who are now�� capable of extracting rare earths from acid rock drainage.

Molecular puzzle pieces

For the proposal to work, the process must be both efficient and selective. The inputs required must be low enough to make the method economically viable, while the outputs must be concentrated enough to provide a high-quality source of rare earth metals.��

That’s why Deng and Ni have decided to target these elements at a molecular level. They propose creating ion-imprinted polymers, made from seafood byproducts. These polymers will act like jigsaw puzzle pieces. Most molecules will bounce right off them, but the targeted element will fit perfectly into the ion-imprinted cavity, allowing the researchers to conserve target elements and filter out the rest.��

Designing these polymers is a monumental task. To increase their chances of success, the researchers will deploy artificial intelligence to help them iterate and refine.

“These elements are like twin brothers when it comes to telling them apart,” Ni said. “Maybe one weighs just a little more than the other. It’s incredibly challenging to differentiate them, but Professor Deng and our research team have proven it’s possible. Now, AI will further enhance the selectivity of our material.”

While the University of Missouri team is busy refining polymers, Marchitto, McKnight, and a to-be-hired PhD student will have their work cut out for them in Colorado. The team will work to identify potential sites for extraction, while also continuing to probe questions about the geochemical processes activated in these waterways.

“We’re also interested in the natural aspects of acid rock drainage that haven’t been explored much, like ‘what controls rare earth concentrations? And, ‘how are they precipitating out in the stream bed?’” Marchitto said. “Knowing more about the fundamentals of the geochemistry will inform what kind of recovery efforts can be used. It’s all connected.”