What does corn husks and tomato husks have to do with electronics? Both can be used to recover valuable rare earth elements, such as neodymium, from electronic waste. Penn State researchers have used microparticles and nanoparticles created from organic materials to capture rare earth elements from aqueous solutions.
Their findings, now available online, will also be published in the November issue of Journal of Chemical Engineering.
“Waste such as corn cobs, wood pulp, cotton and tomato peels often end up in landfills or in compost,” said corresponding author Amir Sheikhi, assistant professor of chemical engineering. “We wanted to convert these wastes into nanoparticles or nanometers capable of extracting rare earth elements from e-waste.”
Rare earth metals are used to make powerful magnets that are used in electric and hybrid car engines, speakers, headphones, computers, wind turbines, television screens, and more. However, extracting these minerals is proving difficult and costly to the environment, according to Sheikhi, as vast land is required to extract even small amounts of the minerals. Instead, efforts have turned to recycling metals from electronic waste such as old computers or circuit boards.
The challenge, Sheikhi said, is effective separation of minerals and waste.
“Using organic materials as a platform, we’ve created high-performance microparticles and nanoparticles that can stick to metals like neodymium and separate them from the fluids around them,” Sheikhi said. “Through electrostatic interactions, negatively charged micro and nanomaterials bind to positively charged neodymium ions, causing them to disintegrate.”
To prepare for the experiment, Sheikhi’s team crushed tomato peels, corn cobs, wood pulp and cotton paper into small, thin pieces and soaked them in water. Then, they chemically reacted with these materials in a controlled manner to break them down into three distinct parts of the functional materials: micro-products, nanoparticles and dissolved biopolymers. The addition of micro-products or nanoparticles to the neodymium solutions initiated the separation process, which resulted in the capture of the neodymium samples.
In this latest paper, Sheikhi has improved the separation process described in previous work and extracted larger samples of neodymium from less concentrated solutions.
Sheikhi plans to expand his separation mechanism to include real-world scenarios and partner with interested industries to further test the process.
“In the near future, we want to test our process on real industrial samples,” Sheikhi said.
We also hope to modify the materials’ selectivity towards other rare earth elements and precious metals, such as gold and silver, so that we can separate them from waste as well. »
In addition to Chikhi, Micah Beecher, a Ph.D. student in chemistry at Penn State and first author of the paper; Brianna Huntington, undergraduate student at Penn State in Agricultural and Biological Engineering; Juliana Dominic, a Penn State biomedical engineering student, contributed to the article.
Penn State supported this work.
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