A simple chemical method could help salvage some of the estimated 300 tonnes of gold used in electronics each year, a study shows.
Current methods for extracting gold from old gadgets are inefficient and can be hazardous to health, as they often use toxic chemicals such as cyanide, the team of researchers at University of Edinburgh in Britain said.
Electrical waste - including old mobile phones, televisions and computers - is thought to contain as much as seven per cent of all the world's gold. The precious metal is a key component of the printed circuit boards found inside electrical devices.
The scientists developed a simple extraction method that does not use toxic chemicals and recovers gold more effectively than current methods.
"We are very excited about this discovery, especially as we have shown that our fundamental chemical studies on the recovery of valuable metals from electronic waste could have potential economic and societal benefits," said lead researcher Jason Love, Professor at University of Edinburgh's School of Chemistry.
By unravelling the complex chemistry underpinning the extraction process, the team discovered a compound that could be used to recover gold more effectively.
Printed circuit boards are first placed in a mild acid, which dissolves all of their metal parts. An oily liquid containing the team's chemical compound is then added, which extracts gold selectively from the complex mixture of other metals.
The findings, published in the journal Angewandte Chemie, could aid the development of methods for large-scale recovery of gold and other precious metals from waste electronics, the team said.
Improving how the precious metal is recovered from discarded electronic devices could help reduce the environmental impact of gold mining and cut carbon dioxide emissions, the researchers said.