What do corn cobs and tomato skins have to do with electronics? They can both be used to recover valuable rare earth elements like neodymium from e-waste. Penn State researchers used micro- and nanoparticles made from organic materials to capture rare earth elements from aqueous solutions.
Their results, now available online, will also be published in the November issue of the Journal of Chemical Engineering.
“Waste like corn cobs, pulp, cotton and tomato skins often end up in landfills or compost,” said corresponding author Amir Sheikhi, assistant professor of chemical engineering. “We wanted to convert this waste into micro- or nanoscale particles capable of extracting rare earths from e-waste. »
Rare earth metals are used to make powerful magnets used in electric and hybrid car motors, speakers, headphones, computers, wind turbines, television screens and more. However, according to Sheikhi, extracting these metals is proving difficult and costly for the environment, as huge areas are required to extract even small amounts of metals. Instead, efforts have turned to recycling metals from e-waste, such as old computers or circuit boards.
The challenge is to effectively separate the metals from the waste, Sheikhi said.
“Using the organic materials as a platform, we have created highly functional microparticles and nanoparticles that can attach to metals such as neodymium and separate them from the surrounding liquid,” said Sheikhi. “Via electrostatic interactions, negatively charged micro- and nanoscale materials bind to positively charged neodymium ions and pull them apart. »
To prepare for the experiment, Sheikhi’s team shredded tomato skins and corn cobs, cut pulp and cotton paper into small, thin pieces, and soaked them in water. They then chemically reacted these materials in a controlled manner to break them down into three distinct fractions of functional materials: microproducts, nanoparticles, and solubilized biopolymers. The addition of microproducts or nanoparticles to neodymium solutions triggered the separation process, resulting in the capture of neodymium samples.
In this latest paper, Sheikhi improved on the separation process demonstrated in previous work and extracted larger sample amounts of neodymium from less concentrated solutions.
Sheikhi plans to extend its disconnection mechanism to real-world scenarios and work with interested industries to further test the process.
“In the near future, we want to test our process on realistic industrial samples,” said Sheikhi.
“We also hope to be able to adjust the selectivity of the materials towards other rare earth elements and precious metals such as gold and silver so that we can also separate them from the waste.” »
Alongside Sheikhi, Mica Pitcher, a Penn State chemistry PhD student and first author of the paper; Breanna Huntington, Penn State undergraduate student in Agricultural and Bioengineering; and Juliana Dominick, an undergraduate biomedical engineering student at Pennsylvania State University, contributed to the article.
Penn State supported this work.
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Materials provided by Pennsylvania. Originally written by Mariah Chuprinski. Note: Content can be edited for style and length.