Researchers from ETH Zurich, Switzerland, have devised a groundbreaking method to extract high-purity gold from electronic waste (e-waste) using an unexpected source: whey protein, a byproduct of the cheese-making process.
Gold, valued for its diverse technical applications across various industries, has long been coveted as a precious metal. However, its status as a non-renewable resource underscores the importance of sustainable extraction methods, particularly as gold becomes increasingly scarce and valuable.
In a recent study by Raffaele Mezzenga, researchers detailed a novel and cost-effective technique for selectively recovering gold from e-waste using whey protein, an unexpected yet abundant food industry byproduct. Researchers created an adsorbent capable of selectively extracting gold from e-waste by transforming whey into a matrix of protein amyloid fibrils.
The resulting nanofibrils formed a gel-like sponge structure by denaturation of whey proteins under acidic conditions and high temperatures. This protein fibril sponge demonstrated remarkable efficiency in absorbing gold ions from a solution containing metal parts extracted from old computer motherboards.
Upon absorbing the gold ions, the protein fibril sponge underwent heat treatment, converting the ions into flakes that eventually melted down into high-purity gold nuggets. Analysis revealed that the extracted gold nuggets consisted predominantly of gold (90.8 wt%), with minimal impurities from other metals such as copper and nickel.
The researchers showcased the commercial viability of their method, highlighting its significantly lower cost than traditional extraction processes. Moreover, the environmental impact of the whey protein-based method proved to be substantially lower, with reduced carbon emissions compared to conventional methods using activated carbon.
Despite its promising results, researchers acknowledge the need for further exploration, particularly in evaluating alternative protein sources to minimize ecosystem damage. Future endeavors aim to refine the technology for market readiness and explore additional sources of gold, including industrial waste from microchip manufacturing and gold-plating processes.
This innovative method represents a significant advancement in sustainable gold extraction from e-waste, offering a cost-effective solution with reduced environmental impact. By harnessing the potential of whey protein, researchers have paved the way for a more efficient and eco-friendly approach to gold recovery from electronic waste.
The study was published in the journal Advanced Materials.
Source: ETH Zurich