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Scientists have developed a highly effective method to recover gold from electronic waste, an advance they say could yield $50 worth of gold for every dollar spent.

Researchers used protein sponges, byproducts from the cheesemaking process, to recover the precious metal from e-waste – a method they claim is sustainable and commercially viable.

In the study, scientists recovered a 450-milligram nugget of 22-carat gold from just 20 old computer motherboards.

The findings suggest the procurement costs for source materials and the energy costs for the entire process are 50 times lower than the value of the gold that can be recovered.

To extract gold, scientists denatured whey proteins in acidic conditions at high temperatures to create a protein slurry that they dried to create a sponge.

Researchers then removed the metal parts from the 20 motherboards, dissolved them in an acid bath, and then placed a protein fibre sponge in the solution to attract the gold ions.

While other metal ions can also adhere to the fibres, gold ions do so much more efficiently.

Scientists then heated the sponge, turning the gold ions into flakes, which they then melted down into a gold nugget.

Using the method, described in the journal Advanced Materials, they could obtain a nugget of around 450 milligrams from the 20 computer motherboards.

The nugget, the study noted, was 91 per cent gold – the remainder being copper – corresponding to 22 carats.

Researchers say the procurement costs for the source materials added to the energy costs for the entire process are 50 times lower than the value of the gold that can be recovered.

“The fact I love the most is that we’re using a food industry byproduct to obtain gold from electronic waste…You can’t get much more sustainable than that,” study coauthor and ETH Zurich professor Raffaele Mezzenga said in a statement.