After soaking the materials in water (as shown in middle column), Penn State researchers chemically reacted shredded wood pulp, cotton paper and ground corncob and tomato peels to convert them into microproducts, nanoparticles and solubilized biopolymers (third column). Adding these microproducts or nanoparticles to solutions containing the rare earth element neodymium triggered the separation process, allowing for capture of the neodymium. Credit: Sheikhi Research Group

Rare earth metals are used to manufacture strong magnets used in motors for electric and hybrid cars, and electronics like headphones, computers, TV screens and more. However, mining these metals is challenging and environmentally costly. Thus, researchers like Amir Sheikhi, assistant professor of chemical engineering at Penn State, have turned to recycling the metals.

“Waste products like corncobs, wood pulp, cotton and tomato peels often end up in landfills or in compost,” said Sheikhi. “We wanted to transform these waste products into micro- or nanoscale particles capable of extracting rare earth elements from electronic waste.”

The challenge lies in efficiently separating the metals from refuse, according to Sheikhi.

In new research published in Chemical Engineering Journal, Sheikhi’s team ground up tomato peel and corncob and cut wood pulp and cotton paper into small, thin pieces and soaked them in water. Then, they chemically reacted these materials in a controlled fashion to disintegrate them into three distinct fractions of functional materials: microproducts, nanoparticles and solubilized biopolymers. Adding the microproducts or nanoparticles to neodymium solutions triggered the separation process, resulting in the capture of neodymium samples.

“Using the organic materials as a platform, we created highly functional micro- and nano-particles that can attach to metals like neodymium and separate them from the fluid that surrounds them,” said Sheikhi. “Via electrostatic interactions, the negatively charged micro- and nano-scale materials bind to positively charged neodymium ions, separating them.”

In this most recent paper, Sheikhi improved upon the separation process demonstrated in previous work and extracted larger sample sizes of neodymium from less concentrated solutions.

Sheikhi said he plans to extend his separation mechanism into real-world scenarios and partner with interested industries to further test the process.

“We also hope to tune the selectivity of the materials toward other rare earth elements and precious metals, like gold and silver, to be able to separate those from waste products as well,” said Sheikhi.

Information provided by Penn State.

Laboratory Equipment is powered by Labcompare, the Buyer's Guide for Laboratory Professionals.