Turning Food Waste Into Gold: Scientists Extract Gold From E-Waste With Whey Sponge
Scientists have come up with an environmentally friendly and extremely profitable solution to the electronic waste crisis. Researchers at ETH Zurich have managed to extract high-purity gold from old computer parts using a special sponge they developed from whey, a by-product of the dairy industry. The study, published in the journal Advanced Materials, offers a solution to both food and electronic waste problems simultaneously.
E-waste, the fastest-growing type of solid waste on a global scale, reached 61.3 million tons in 2023.
Even though devices like smartphones and computers harbor a significant amount of valuable gold, the current recycling methods require environmentally harmful chemicals and are quite costly. However, a team led by Raffaele Mezzenga, Professor of Materials Science at ETH Zurich, has developed an extremely affordable and environmentally friendly alternative.
The method is based on transforming the protein fibers in whey into a gel through processing in an acidic environment and at high temperatures.
This dried gel transforms into a highly porous protein sponge.
To test the system, researchers dismantled the motherboards of 20 old computers, converting the metals into ions by dissolving them in a mixture of nitric and hydrochloric acid. When the prepared protein sponge was immersed in this solution, it was observed that gold ions adhered to the sponge much more strongly compared to other metals. The sponge was then incinerated at a temperature of 1000°C; while the protein structure turned to ash, the melted gold remained behind.
As a result of the process, a gold ingot weighing 450 milligrams with a purity of 91% (22 carats) was obtained from 20 motherboards.
Professor Mezzenga emphasized that the value of the gold obtained is a whopping 50 times higher than the cost of raw materials and energy used in the process. Highlighting that the method can be conducted with basic equipment such as freeze dryers and standard vacuum ovens, Mezzenga revealed that they are continuing their efforts to commercialize and scale up the technology.
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