In a modern-day alchemical feat, Professor Raffaele Mezzenga and his team from ETH Zurich have devised a groundbreaking method to recover gold from electronic waste using a byproduct of the cheesemaking process. Electronic waste, abundant in valuable metals including gold, presents a lucrative opportunity for resource recovery amid rising demand for precious metals.
Conventional methods for gold recovery from electronic waste are often energy-intensive and reliant on toxic chemicals. However, Mezzenga’s team has introduced a highly efficient, cost-effective, and sustainable alternative: a sponge made from a protein matrix derived from denatured whey proteins.
The manufacturing process involves denaturing whey proteins under acidic conditions and high temperatures, causing them to aggregate into protein nanofibrils, which are then dried to create the sponge. In laboratory experiments using electronic motherboards, the researchers dissolved metal parts in an acid bath to ionize the metals.
When the protein fiber sponge was introduced into the metal ion solution, gold ions selectively adhered to the protein fibers, demonstrating superior efficiency compared to other metal ions. Subsequent heating reduced the gold ions into flakes, which were melted down to yield a gold nugget.
Economically viable and environmentally sustainable, the technology offers significant cost savings, with procurement and energy costs estimated to be 50 times lower than the value of the recovered gold. The researchers aim to further develop the technology for commercialization, exploring additional sources of electronic waste as well as industrial waste from microchip manufacturing or gold-plating processes.
Mezzenga highlights the sustainability of the method, emphasizing the transformation of two waste products—electronic waste and food industry byproducts—into valuable gold. With its innovative approach and potential for widespread application, this breakthrough heralds a new era of resource recovery and environmental stewardship in the electronic waste recycling industry.
