There are a lot of important metals in our devices, but extracting them is expensive. Researchers have used whey, a waste product from cheese making, to extract gold cost-effectively.
Recently, scientists developed a sponge created from a waste product of cheesemaking capable of absorbing metals from electronic waste. The study published in the January edition of Advanced Materials notes that the organic material is particularly efficient in sucking up gold, so much so that it can retrieve $50 worth of gold for every dollar spent on the recycling process.
According to the National Institutes of Health, dairies dispose of over 100 million tons of whey each year.
The scientists first denature the dairy proteins by heating the whey in an acid bath. This step creates the amyloid nanofibrils used to form the sponge. The electronic components are then dissolved in acid to create an ionic solution rich in gold and copper.
https://interestingengineering.com/innovation/scientists-extract-gold-from-electronic-waste-using-a-cheese-byproduct
When the sponge is reheated, it leaves behind flakes of gold and some copper.
Darcy Hitchcock 