Scientists have developed a new composite material that extracts gold from e-waste ten times more efficiently, offering a sustainable, power-free alternative to traditional methods.
Researchers from Singapore, the UK, and China have developed a composite material that is ten times more effective at extracting gold from electronic waste (e-waste) than previous materials. The eco-friendly composite, made from graphene oxide and chitosan—a natural biopolymer—filters gold without requiring an external power source. Its efficiency and sustainability make it a promising alternative to the energy-intensive techniques currently used.
Efficient extraction of gold from e-waste has dual benefits: it reduces the amount of waste sent to landfill and reduces dependency on mining and refining new gold, which often involves toxic chemicals such as cyanides. Although e-waste management is a relatively new field, many existing methods, such as electrolysis, are costly and energy-intensive.
The research team, led by Kostya Novoselov and Daria Andreeva from the National University of Singapore’s Institute for Functional Intelligent Materials, chose graphene and chitosan for their unique properties. Graphene has a very large surface area, making it an excellent material for adsorbing ions, and chitosan is a natural reducing agent that catalyses the conversion of gold ions into solid metal form.
As reported by Physics World, while graphene and chitosan alone do not outperform traditional methods such as activated carbon, combining them results in a material with enhanced adsorption capacity and catalytic reduction. “Combining them enhances both graphene’s adsorption and chitosan’s reduction abilities, resulting in a more efficient and suitable gold recovery process,” Andreeva explained.
High-efficiency extraction and fast results
To create the composite, the team engineered chitosan macromolecules to self-assemble onto graphene oxide flakes. This activates ion-binding sites that capture gold ions, allowing the composite to extract gold efficiently. When a gold ion binds to one site, it causes nearby sites to bind additional ions, resulting in a cooperative effect that boosts extraction efficiency. Previously, the researchers used similar methods to develop structures like artificial ionic channels, corrosion-resistant coatings, and bioelectrochemical systems.
Once gold ions are captured on the graphene, the chitosan catalyses their reduction, converting them into solid metallic gold. “This dual action of adsorption and reduction makes the process highly efficient and eco-friendly, avoiding the harsh chemicals often used in traditional gold recovery from e-waste,” says Andreeva.
Tests on a real waste mixture from SG Recycle Group SG3R demonstrated the composite’s exceptional performance. The material extracted nearly 17 grams of Au3+ ions per gram of composite and just over 6 grams of Au+ ions—values ten times higher than what’s achievable with existing adsorbents. The composite’s extraction efficiency is over 99.5% by weight, compared to a 75% maximum using previous techniques. Additionally, the process is ultrafast, taking just 10 minutes, while other graphene-based adsorbents require days to complete extraction.
No external power required
The composite’s unique structure lets it to adsorb and reduce gold ions without an external power source. Instead, the method depends on the natural kinetics of chemisorption in the graphene oxide-chitosan nanostructures. Multiple binding sites enable chemical reduction, creating a clean, efficient, and eco-friendly method for gold recovery.
Although the research focused on gold recovery, the team sees potential for applying the same technique to extract silver, platinum, and palladium from e-waste and mining residues. Beyond metal recovery, the technology could help in environmental remediation efforts, filtering heavy metals from polluted water and industrial discharge, ultimately helping reduce metal pollution in ecosystems.
Future uses and sustainability
The team believes the technology it’s developed could also support sustainable decarbonisation, clean hydrogen production, advanced computing, and medical applications. They are also investigating ways to regenerate and reuse the composite material, which would further reduce waste and enhance sustainability. “Our ongoing research aims to optimise the material’s properties, moving us closer to a scalable, eco-friendly solution for e-waste management and beyond,” says Andreeva.
