Highlights
- Penn State researchers discover LanD protein that can efficiently separate rare earth elements, particularly light REEs like neodymium and praseodymium.
- The LanD protein, working in tandem with previously discovered LanM, offers a potential breakthrough in REE separation technology, challenging China’s dominance in the sector.
- This protein-based approach could revolutionize REE processing, making it more economical, efficient, and environmentally friendly.
Penn State has emerged as a hotbed for research to potentially help transform the rare earth elements (REE) sector, including the global supply chain. As Rare Earth Exchanges reported recently, the university has received multiple grants in an effort to help transform the REE processing market. Now Penn State led by Joseph Cotruvo, Jr., a chemistry professor, led another investigation not only finding a novel protein that naturally houses an unusual binding site that can differentiate between rare earth elements, but also the means of improving that process. Called LanD, the protein can enrich neodymium and praseodymium over other similar REEs. The authors of the study believe they could be in pursuit of a revolutionizing disruption of the REE separation process. Nothing short of that will turn around what has emerged as China’s runaway domination of the REE process space. The study’s lead author has filed patents for the technology.
The recent study results were published (opens in a new tab) in the Proceedings of the National Academy of Sciences.
Does China control 80%+ of the REE production in the global value chain?
Yes.
Is the problem sourcing and mining the minerals?
No. There are lots of sources of REEs. While more mines may be helpful and there are methods to access REEs via recycling, although not all recycled REE products are of the same quality, the real challenge involves the need to disrupt the processing process in the REE value chain. This is where China wields a monopoly.
What is the challenge the industry faces to disrupt the supply chain?
As the Penn State professor cited in Phys.Org the challenge with rare earth elements is that each one has unique properties that on the one hand make themincredibly useful for varying applications, yet on the other handit’s extremely difficult to separate them, while current separation methods are not only inefficient but also depend on the use of toxic chemicals.
What could this protein-based approach do to revolutionize the REE separation process?
The hope is that such an innovation could help transform the separation process, making It far more economical, efficient, and cleaner.
So, a more effective and efficient separation technology-powered process would help shake up the supply chain?
Yes. A more effective separation approach could help secure a national supply of REEs.
What are some of the differences between heavy and light REEs?
The 17 REEs either fall into the heavy or light REE category. For example, 15 metals called "lanthanides," are commonly divided into "light" and "heavy" groups, with the light REEs far more prevalent.
The most common light REEs, lanthanum and cerium, don’t bring much value, while select light REEs such as praseodymium and neodymium bring a higher value.
Neodymium is an important component for permanent magnets used in smartphones and renewable energy machinery like wind turbines, while praseodymium is often combined with neodymium for these applications.
Has Professor Cotruvo and colleagues in the lab discovered other important proteins that may help separate REEs?
Yes. As reported by Phys.Org (opens in a new tab) and Penn State (opens in a new tab) have reported, Cotruvo's lab previously identified another protein, LanM (opens in a new tab), that binds to all REEs with high specificity (opens in a new tab) over any other metal. It does this in a fashion like a lock and key mechanism, with the protein being the lock and the REE a key. When the protein binds a REE, it undergoes a change in shape analogous to the key turning in the lock.
The LanM proteins studied to date are very good at differentiating between heavy REEs, but they do not do well separating the light REEs, akin to a keyhole that fits a few different keys.
How is LanD protein an improvement of the previous M version?
The LanD protein represents an improvement, with superior separation abilities among the light REEs that at least as good, if not superior to current industry practices. With a unique, never-before-seen binding site—where the metal "key" can lock into the protein—LanD's natural REE separation abilities can be engineered to be even more efficient, offering new hope for a greener rare earth element mining industry.
According tothe investigator: "Current efforts are concentrated towards optimizing REE separation to make it less labor and material intensive," Cotruvo said. "But this organism, Methylobacterium extorquens, a bacterium found abundantly in nature, makes proteins that seem to have already solved the problem."
So, what is Methylobacterium extorquens?
Methylobacterium extorquens is a species of bacteria known for its ability to grow on one-carbon compounds like methanol, and prefers to use specific REEs, mostly lanthanum and cerium, to support that growth.
So, do both LanM and LanD work together?
Yes, it turns out that the two proteins work in tandem, with LanD binding to the lanthanides that the bacterium takes up but doesn't need and delivering them to LanM, where they are sequestered. Those lanthanides, while not important to the bacteria, are the ones that are most important to tech production according tothe Penn State scientist.
"The bacterium can take up a broader group of lanthanides than the small subset that it prefers to use, so it needs a way to prevent those undesirable lanthanides from interfering with the functions of the desirable lanthanides in the cell," Cotruvo said. "LanD and LanM appear to work together to do this sorting, which explains why the previously identified LanM protein is good at lanthanide separations in general."
He added that LanD, with its unique binding site, is much better for the light REEs specifically.
"LanD conveniently binds best to neodymium, which is by far the most valuable of the light REEs," Cotruvo said. "While the naturally occurring LanD protein exhibits a preference for neodymium, we re-engineered it to more effectively be able to extract neodymium from a mixed solution of light REEs, disfavoring the other REEs that are of lesser value."
So what other details are relevant?
Cotruvo and colleagues report finding that engineering the LanD binding site allows separations producing desired neodymium and praseodymium to become much more effective.
What research targets have the authors publicly disclosed?
They hope to be able to narrow down protein size yet boost the preference of this binding site even more—and implement it in a larger-scale separation. In this way the established site represents a starting point for chemists and engineers to develop highly specific proteins to perfect sorting of other tricky-to-separate elements, Cotruvo said.
Also, the researchers, given their acknowledgement that LanD and LanM specialize in separation of different REEs, have the potential to be mobilized jointly to process to separate complex REE sources like ores.
"The LanD protein is a promising way to improve REE separation practices," he said. "And we're working on making it even better, to pave a path toward more effective, greener rare earth mining."
Who else was involved with the study?
Joseph Cotruvo, PhD (opens in a new tab), Professor Chemistry, Penn State
Wyatt Larrinaga and Jonathan Jung, graduate students in chemistry; Chi-Yun Lin, postdoctoral researcher in chemistry; and Amie Boal, professor of chemistry and of biochemistry and molecular biology.
Daniel
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