Discarded phones, computers and other electronics contain valuable metals, including gold.
Recovering those metals, however, often requires large amounts of chemicals that can create waste and make recycling complicated and expensive.
Now, researchers at the University of Illinois Urbana-Champaign have developed a molecule that could allow electricity to replace many of those chemical reagents.
The approach could eventually make recovering gold and other valuable metals from electronic waste cleaner, simpler and more energy-efficient.
The research, led by chemical and biomolecular engineering professor Xiao Su, was published in ACS Energy Letters.
The work builds on a system Su’s team reported in 2024. That technology used an electrically controlled process known as liquid-liquid extraction to recover gold from electronic waste. Traditional liquid-liquid extraction separates metals by moving them between two liquids that do not mix, often using substantial amounts of acids, bases and other chemicals.
The earlier system showed that electricity could replace many of these chemicals. But additional reagents were still required to complete the extraction cycle.
The researchers have now tackled that problem by redesigning the molecule responsible for capturing the metal.
Their new molecule performs three important jobs at once. It can selectively grab metal ions, remain dissolved in the organic liquid used for extraction and carry a permanent electrical charge.
That built-in charge is particularly important because it allows the liquid to conduct electrical current. Researchers can therefore use electricity to control the chemical reactions needed to capture and release metals without relying on intermediate chemical reagents.
In simple terms, the molecule can be electrically activated to bind to a desired metal. It then carries that metal into another liquid. Electricity can subsequently trigger the release of the metal so that it can be collected.
In laboratory experiments, the researchers successfully used the system to selectively recover gold from solutions produced by processing electronic waste.
The new approach reduced the amount of chemicals required by roughly one to two orders of magnitude compared with conventional approaches, according to the researchers. Using fewer chemicals could also mean less chemical waste and a simpler overall recycling process.
Gold, however, is only the beginning.
The researchers say one of the most important results of the study is a new set of principles for designing electrically controlled molecules that target specific metals. By changing the chemical structure of the extraction molecule, scientists could potentially adapt the same basic platform to recover many different valuable materials.
Possible targets include platinum-group metals found in used vehicle catalytic converters, as well as critical elements contained in mine tailings and other industrial waste streams.
This could become increasingly important as demand grows for critical minerals used in electronics, renewable energy technologies, batteries and other industries.
The technology is still at the laboratory stage, and researchers now need to determine how effectively it can operate on an industrial scale. The team is developing additional extraction molecules and exploring the use of computer modeling and artificial intelligence to speed up the search for new designs.
If those efforts succeed, future metal recycling facilities could depend much less on large quantities of chemical reagents. Instead, carefully designed molecules and electricity could work together to pull valuable metals out of waste—turning discarded electronics into a cleaner source of critical materials.
