Inventors create nanofibrillar sponges from cheese waste. Returns up to 50 times the value of the investment.
A team of ETH Zurich researchers has developed a revolutionary invention that makes it easy and environmentally friendly to extract gold from electronic waste. The method, which uses a by-product of the food industry, makes it possible to extract the precious metal without the use of polluting chemicals and opens up new possibilities for technological recycling.
The key to this innovation is nanofibril sponges derived from whey protein, a waste product from cheese production. These structures can attract and retain gold ions contained in discarded electronic circuits, allowing them to be recovered in an efficient and environmentally friendly way. This cannot be done in conventional systems such as the one shown in the video below.
The procedure starts with the denaturation of proteins under controlled temperature and acidity conditions. This process produces a suspension of nanotubes which, when dried, becomes a highly absorbent sponge. When immersed in a solution obtained by dissolving the metal components of electronic devices, the sponge is very effective in trapping gold ions.
Experimental results
The results of the study, published in the journal Advanced Materials, show that 450 milligrams of 22-carat gold nuggetcan be extracted from just 20 old computer motherboards. To complete the extraction, the sponge is heated, which reduces the amount of ions collected and produces solid gold particles, which are then melted.
The efficiency of this system makes it an incredibly cost-effective alternative. According to the researchers, for every dollar invested in the process , up to USD 50 worth of gold can be produced. In addition to allowing the metal to be collected, the nanotube aerogels act as templates for the formation of single crystal flakes, thus improving the quality of the metal extracted.
