Scientists have developed a novel way to recycle toxic waste — extracting gold from old electronics using a byproduct of a staple cuisine in many cultures.
Researchers at Switzerland's ETH Zurich announced in a press release that they used "denatured" whey proteins (the watery portion of cheese that separates from curds) to create a sponge to recover gold ions from e-waste.
To extract the gold, researchers placed the whey sponge into a metal ion solution. The gold flakes then adhered to the protein fibers. Heating the sponge allowed the team to obtain around 450 milligrams of gold from 20 computer motherboards (around 22 karats).
Their findings, published in the journal Advanced Materials, provide a path toward more sustainable recycling practices for an increasingly concerning issue.
According to the World Health Organization (WHO), "e-waste is the fastest-growing waste stream in the world," with more than 59 million tons generated globally in 2019 alone.
Lead and other toxic substances, such as mercury, are commonly released into our environment in the event of improper disposal or recycling. This creates a conundrum about keeping our communities connected with modern technology while reducing public health concerns.
Recycling solutions do exist. For example, major companies, including Amazon and Best Buy, have programs that help consumers recycle and dispose of old electronics.
However, per the WHO, less than 20% of all e-waste was officially collected and recycled in 2019. Moreover, as detailed in the ETH Zurich press release and by ZME Science, traditional e-waste recycling methods are energy-intensive and generally require toxic chemicals to harvest precious metals.
The breakthrough by ETH Zurich researchers sidesteps this problem. It could also help reduce food-industry waste — and thus eliminate some production of planet-warming gases like methane as unused proteins decompose in landfills.
"The fact I love the most is that we're using a food industry byproduct to obtain gold from electronic waste," Raffaele Mezzenga, a professor from ETH Zurich's Department of Health Sciences and Technology, said in the release. "You can't get much more sustainable than that!"
Mezzenga believes the process is commercially viable, with costs expected to be 50 times lower than the value of the gold obtained from the waste.
Researchers will now investigate whether they can make "protein fibril sponges" from other food-waste byproducts, and they intend to test their method on industrial waste from sources such as microchip manufacturing and gold-plating.
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