Gold is known for its precious and inert metal features; now, it is known for its technical applications in electronics, catalysis, aerospace, electroplating, nanotechnology, medicine, and biotechnology. It has excellent conductivity, ductility, reflectivity, biocompatibility, and stability.
Current methods of gold recovery are resource-intensive, necessitating the development of more efficient extraction materials.
Scientists at ETH Zurich have found an effective way to recover gold from e-waste. Their method is very efficient, cost-effective, and far more sustainable: with a sponge made from a protein matrix. Using this method, scientists successfully extracted gold from electronic waste.
Scientists denatured whey proteins under acidic conditions and high temperatures. This allowed them to aggregate into protein nanofibrils in a gel. Once this gel dried, scientists created a sponge from these protein fibrils.
The scientists recovered the electronic motherboards from twenty obsolete computer motherboards and extracted the metal bits to recover gold in the lab experiment. To ionize the metals, they dissolved these components in an acidic solution.
The gold ions stuck to the protein fibers when they submerged the protein fiber sponge in the metal ion solution. Although gold ions stick to the fibers far more effectively than other metal ions, they can still do so.
The next step involves heating the sponge. As a result, the gold ions were reduced to flakes, which the scientists then melted to form gold nuggets. Out of the 20 computer motherboards, they could extract a nugget weighing about 450 milligrams in this manner. The nugget contained 91 percent gold or 22 carats, with copper making up the remaining percentage.
Mezzenga’s calculations demonstrate that the new method is commercially viable: the value of the recoverable gold is fifty times greater than the cost of procuring the source materials plus the energy expenditures for the complete process.
The team’s next goal is to advance and prepare the technology for commercialization. There are other potential sources, but electronic waste is the most promising beginning product from which they hope to extract gold. These consist of industrial waste from gold-plating or microchip manufacturing procedures. Furthermore, scientists intend to explore the possibility of producing protein fibril sponges using additional byproducts or waste materials from the food sector that are high in protein.
Mezzenga says, “The fact I love the most is that we’re using a food industry byproduct to obtain gold from electronic waste. The method transforms two waste products into gold. You can’t get much more sustainable than that!”
Journal Reference:
- Peydayesh M, Boschi E, Donat F, Mezzenga R: Gold Recovery from E-​Waste by Food-​Waste Amyloid Aerogels. Advanced Materials 2024, 2310642, DOI: 10.1002/adma.202310642