Swiss researchers from ETH Zurich developed a process to extract gold from electronic waste using whey proteins from cheese production. This new method demonstrates the potential of electronic waste, often neglected and ending up in landfills, as a valuable source of gold that can be reused for sustainable gold recovery.
The process involves creating a sponge made from protein fibers obtained from dairy byproducts, specifically amyloid protein nanofibrils derived from whey. These nanofibrils are used to manufacture porous aerogels that act like a sponge for gold. When immersed in a solution of metals extracted from computer motherboards, the sponge efficiently attracts dissolved gold ions.
To obtain the gold, the scientists first dissolve the metallic components of the electronic waste in an acid bath, releasing the metals in the form of ions. The protein fiber sponge selectively captures the gold ions, while other metals such as copper and nickel adhere to a lesser extent. The gold ions adhered to the protein fibers are then reduced to solid gold particles upon heating.
Once the gold is captured, the sponge is heated, which reduces the captured gold ions to solid flakes that are then melted to form a small nugget weighing about 450 milligrams, containing 91% pure gold and classified between 21 and 22 carats. From just 20 old computer motherboards, the researchers were able to extract a gold nugget valued at approximately $33.
"You can't get anything more sustainable than that!" said Professor Raffaele Mezzenga of ETH Zurich [https://www.infobae.com/tecno/2025/02/06/sabias-que-tienes-una-mina-de-oro-entre-manos-con-telefono-y-pc-hasta-oro-de-22-kilates/]. "The costs associated with acquiring raw materials and energy consumption are 50 times lower than the value of the recovered gold," Mezzenga noted [https://eldiariony.com/2025/02/06/la-cantidad-de-oro-que-termina-en-la-basura-cuando-tiramos-un-celular-o-computadora/].
The researchers have also demonstrated that the aerogels can act as templates to convert gold ions into monocrystalline flakes, improving the quality of the recovered metal.
Electronic waste is a growing problem worldwide, with millions of devices discarded every year. The metallic components of electronic waste, such as computer motherboards, decompose in an ionic solution.
This article was written in collaboration with generative AI company Alchemiq