Despite rare earth elements’ importance in manufacturing cell phones, magnets and a host of other consumer and commercial electronics, the lack of a sustainable, environmentally friendly approach to obtaining these metals has led to a global shortage, according to Amir Sheikhi, associate professor of chemical engineering.
Sheikhi is the principal investigator on a paper, recently published in Advanced Functional Materials, that proposes a novel technology of isolating and recovering dysprosium, a rare earth element used to manufacture semiconductors, engines, generators and more.
Commercialized approaches to separating rare earth elements primarily use solvents, dissolved liquids or solids that can break apart minerals, and require rooms full of machinery and chemicals to function, according to Sheikhi.
To improve this inefficient and pollutant process, the team turned to cellulose. They adjusted the cellulose’s molecular structure to create a very small, crystalline material, only about 100 nanometers long ,1,000 times smaller than the width of a human hair. This nanocellulose is covered with tiny, hair-like cellulose chains at both ends – known as anionic hairy cellulose nanocrystals (AHCNC).
The team then added their nanocellulose to a water-based solution of neodymium and dysprosium, observing how the nanocellulose was able to separate the dissolved metals through a process called adsorption, where a surface collects and holds ions from a liquid or dissolved solid.
On top of that, our process is very straightforward and efficient. We just add our #nanocellulose to a solution and separate the metals.”
Further study of the samples revealed how the hairs found on AHCNC can essentially act as a filter to target and separate #dysprosium ions specifically. Sheikhi said this surprised the team, who had initially thought adjusting the functional group type, or specific sets of atoms that determine how elements will chemically react with one another, of the cellulose would be key to optimizing separation.
“After comparing this behavior side-by-side with other cellulose-based platforms, we determined it's not just the functional group type of the material that facilitates this selectivity. “It’s the structure of the material itself and the position of the functional groups, which showcases the unique properties of these hairy nanostructures.
With more development, the team said they believe this approach could offer a faster, cleaner and commercially practical way to recycle dysprosium and other rare earth elements. Moving forward, the researchers plan to test their method’s viability isolating other rare earth elements and critical minerals. They also plan to further optimize the cellulose, with the goal of preparing the technology to scale for practical use in factories and laboratories around the U.S.
source : Penn State University
