LONDON — They say one person’s trash is someone else’s treasure. Now, researchers from Imperial College London are giving new meaning to that old phrase. Scientists have discovered that gold recycled from discarded electronics can act as “catalysts” to help make drugs more sustainable.
Today, most gold from electronic waste, such as old SIM cards, end up in landfills. Reclaiming and re-using discarded gold for drug manufacturing purposes reduces the need for more mining, researchers explain. Current drug producing catalysts typically consist of various rare metals, usually extracted by expensive, energy-exhaustive, and damaging mining efforts.
This latest approach to extracting gold was developed at the University of Cagliari in Italy, while the process of utilizing the recovered gold was developed by the team at ICL.
Why do electronics end up in landfills in the first place?
Waste electrical and electronic equipment (WEEE) is notoriously difficult to separate and break down just to extract their individual components. These processes usually involve tons of energy and harsh chemicals. Electronics end up in landfills and dumps because it doesn’t make financial sense to invest in extracting individual components. However, WEEE do indeed contain numerous metals that manufacturers could repurpose for various additional products.
Establishing new low-cost, low-energy and non-toxic ways to recover and use the metals hidden in discarded electronics is key to creating a more sustainable electronics industry in general, the research team says.
“It is shocking that most of our electronic waste goes to landfill and this is the opposite of what we should be doing to curate our precious elemental resources. Our approach aims to reduce the waste already within our communities and make it a valuable resource for new catalysts, thereby also reducing our dependence on environmentally damaging mining practices,” says lead researcher Professor James Wilton-Ely, from the Department of Chemistry at Imperial College London, in a university release.
“We are currently paying to get rid of electronic waste, but processes like ours can help reframe this ‘waste’ as a resource. Even SIM cards, which we routinely discard, have a value and can be used to reduce reliance on mining and this approach has the potential to improve the sustainability of processes such as drug manufacture.”
How does the process work?
To start, professors Angela Serpe and Paola Deplano, from the University of Cagliari, constructed a new low-cost way to extract gold and other metals from discarded electronics like printed circuit boards (PCBs), SIM cards, and printer cartridges (under mild conditions). The patented process developed by the two scientists involves selective steps for the sustainable leaching and recovery of base metals including nickel, then copper, silver, and lastly, gold – all via green and safe reagents.
It’s important to note, however, that the gold derived from that process is part of a molecular compound, and this is not usable again with electronics without investing a whole lot of energy to obtain the gold. In pursuit of a concrete use for this compound of recovered gold, the team of Professor Wilton-Ely and his colleague, Professor Chris Braddock, looked into if they could apply it as a catalyst in the production of useful compounds like pharmaceutical intermediates.
A catalyst increases chemical reaction rates, all while remaining unchanged itself. Catalysts are a component in most material-producing processes. Researchers tested the gold compound against numerous reactions frequently used in the production of pharmaceuticals. For instance, the creation of anti-inflammatory and pain-relief drugs.
Study authors observed that the gold compound performed just as well, or better, than currently used catalysts. Even better, the gold compound is also reusable, further increasing sustainability.
Could it work with other metals?
All in all, study authors believe that if extracting gold from discarded electronics were to be made economically viable, it would foster “spin-off uses” for other components recovered in the process. For example, during the process which separates copper, nickel, and plastic itself, all of those components can hypothetically help create new goods.
“By weight, a computer contains far more precious metals than mined ore, providing a concentrated source of these metals in an ‘urban mine,’” explains Sean McCarthy, the PhD student leading the research in the lab at Imperial.
“Research like ours aims to contribute to the cost-effective and sustainable recovery of metals by building a bridge between the supply of precious metals from scrap and industrial demand, bypassing the use of virgin raw materials,” Prof. Serpe concludes.
Moving forward, study authors are focusing on developing this approach even further so they can apply it to the recovery and re-use of the palladium content in end-of-life automotive catalytic converters. Palladium is a common catalyst, and even more expensive than gold.
The findings appear in the journal ACS Sustainable Chemistry & Engineering.
