Turning Old Electronics Into Gold: A Recycling Breakthrough

Researchers at Cornell University have created a sustainable method to extract gold from electronic waste and use it as a catalyst to transform CO2 into valuable organic materials.

This process provides an eco-friendly alternative to traditional extraction methods, utilizes vast amounts of e-waste, and helps mitigate CO2 emissions, showcasing a promising avenue for environmental conservation and resource recovery.

Innovative Gold Recovery from E-Waste

A team of researchers led by Cornell University has created a method to extract gold from electronic waste and repurpose it as a catalyst to convert carbon dioxide (CO2), a major greenhouse gas, into useful organic materials.

This innovative approach could provide a sustainable solution for some of the 50 million tons of e-waste generated annually, of which only 20% is currently recycled. Amin Zadehnazari, a postdoctoral researcher in the lab of Alireza Abbaspourrad, the Yongkeun Joh Associate Professor of Food Chemistry and Ingredient Technology in the College of Agriculture and Life Sciences, highlighted the potential environmental and practical benefits of this process.

Breakthrough in Selective Gold Adsorption

Zadehnazari developed two vinyl-linked covalent organic frameworks (VCOFs) to efficiently remove gold ions and nanoparticles from discarded circuit boards. One of these VCOFs demonstrated an impressive ability to capture 99.9% of the gold while minimizing the extraction of other metals, such as nickel and copper, ensuring a highly selective recovery process.

“We can then use the gold-loaded COFs to convert CO2 into useful chemicals,” Zadehnazari said. “By transforming CO2 into value-added materials, we not only reduce waste disposal demands, we also provide both environmental and practical benefits. It’s kind of a win-win for the environment.”

Abbaspourrad is corresponding author and Zadehnazari lead author of “Recycling E-waste Into Gold-loaded Covalent Organic Framework Catalysts for Terminal Alkyne Carboxylation,” which was published on December 30 in Nature Communications.

Eco-Friendly Gold Extraction Techniques

Electronics waste is a literal gold mine: It’s estimated that a ton of e-waste contains at least 10 times more gold than a ton of the ore from which gold is extracted. And with an anticipated 80 million metric tons of e-waste by 2030, it’s increasingly important to find ways to recover that precious metal.

Traditional methods for recovering gold from e-waste involve harsh chemicals, including cyanide, which pose environmental risks. Zadehnazari’s method is achieved without hazardous chemicals, using chemical adsorption – the adhesion of particles to a surface.

Advantages of Novel COF-Based Methods

Covalent organic frameworks (COFs) are porous crystalline materials known for having multiple potential uses, including chemical sensing and energy storage. Zadehnazari synthesized two VCOFs, using tetrathiafulvalene (TTF) and tetraphenylethylene (TPE) as building blocks.

The TTF-COF showed superior gold adsorption due to its being rich in sulfur, for which gold has a natural affinity. In addition to displaying high adsorption capacity, the TTF-COF withstood 16 washings and reuses, with little loss of adsorption efficiency.

And under ambient CO2 pressure at 50 degrees Celsius (122 degrees Fahrenheit), the resulting gold-loaded COF efficiently converted CO2 into organic matter via carboxylation.

Other methods for recovering gold and other precious metals from e-waste usually aren’t as selective as Zadehnazari’s idea and result in impurities, Abbaspourrad said.

“Knowing how much gold and other precious metals go into these types of electronic devices, being able to recover them in a way where you can selectively capture the metal you want – in this case, gold – is very important,” Abbaspourrad said.

Reference: “Recycling e-waste into gold-loaded covalent organic framework catalysts for terminal alkyne carboxylation” by Amin Zadehnazari, Florian Auras, Ataf Ali Altaf, Amin Zarei, Ahmadreza Khosropour, Saeed Amirjalayer and Alireza Abbaspourrad, 30 December 2024, Nature Communications.
DOI: 10.1038/s41467-024-55156-3

Co-authors include Abbaspourrad lab postdoctoral researcher Amin Zarei; former postdoctoral researcher Ataf Ali Altaf; lab research associate Ahmadreza Khosropour; Saeed Amirjalayer of the University of Munster, Germany; and Florian Auras of Dresden University of Technology, also in Germany.

The research made use of the Cornell Center for Materials Research and the Cornell NMR facilities, both of which are funded by the National Science Foundation.

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