Researchers in the United States have developed a novel separation process capable of selectively distinguishing between different members of the rare earth element group.
Rare earth elements (REEs) are critical raw materials for numerous advanced technologies. However, their availability is limited because production is highly concentrated in a few regions. As a result, new extraction and recovery methods are being developed worldwide. These include approaches using algae, genetically engineered viruses, and unconventional sources such as discarded energy-saving lamps. Beyond reducing import dependency, these innovations aim to improve environmental sustainability, as conventional extraction methods are energy-intensive and often rely on hazardous chemicals.
A major technical challenge in developing new production technologies is distinguishing between so-called light and heavy rare-earth elements, which exhibit distinct chemical properties. Separating individual elements within this group is particularly complex. At Pennsylvania State University, researchers have now developed a technology that leverages cellulose, an essential structural component of plant cell walls. Using cellulose-based compounds, the research team successfully extracted the light rare earth element neodymium in initial trials.
Targeted Extraction Method for Dysprosium
The method was subsequently refined to enable the selective separation of dysprosium, a heavy rare earth element. Dysprosium is an essential component in high-performance permanent magnets and nuclear fuel rods. Demand for this element is expected to rise significantly in the coming years, while its production remains largely concentrated in China.
To achieve selective binding, the researchers modified the molecular structure of cellulose, creating a nanoscale crystalline material approximately 100 nanometers in size—about 1,000 times thinner than a human hair. The nanocellulose particles are coated at both ends with hair-like cellulose chains known as anionic hairy cellulose nanocrystals (AHCNC).
The material was then introduced into an aqueous solution containing dissolved neodymium and dysprosium ions to test whether selective adsorption could be achieved. Adsorption is a surface-driven process in which ions from a liquid phase adhere to a solid interface. According to the researchers, the AHCNC exhibited unique behavior: the chemically modified chains within the “hairs” contracted significantly in the presence of dysprosium, indicating specific molecular sensitivity and a preferential interaction with this heavy rare earth element.
According to the study’s lead author, Amir Sheikhi, this represents the first known cellulose-based adsorption material capable of selectively separating heavy from light rare earth elements.
The research team now aims to further develop the approach for practical implementation in industrial and laboratory settings in the United States. Future work will focus on scaling the technology and extending it to isolate additional rare earth elements and other critical minerals.
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