Selective Recovery of Precious Metals from Aqueous Solutions

The selective recovery of precious metals—principally gold, silver and platinum group elements—from aqueous media has emerged as a critical component of circular economy strategies and environmental protection. It addresses the dual challenge of resource scarcity and pollution associated with electronic waste, mining effluents and industrial wastewater. Contemporary methods exploit tailored adsorbent materials that combine high capacity, rapid kinetics and exceptional selectivity even in complex matrices containing competing ions. Key approaches integrate adsorption with in situ reduction or crystallisation to yield metallic forms directly, thus minimising downstream processing. Advances in materials design, from porous organic frameworks to functionalised nanocarbons and biopolymeric aerogels, have enabled fine control over binding sites, redox chemistry and mass transport. Life-cycle assessments and techno-economic analyses increasingly demonstrate the feasibility of scaling these technologies to industrial levels, promising sustainable recovery pathways that conserve finite mineral resources while reducing environmental impact.

Research from Nature Portfolio

Recent studies have introduced a porous organic polycarbene adsorbent in which carbene functional sites act as nanotraps for gold ions. This material exhibits an ultrahigh recovery capacity exceeding two grams of gold per gram of adsorbent and achieves near-complete extraction in electronic-waste leachates, driven by robust metal-carbene bond formation and local reduction of gold ions to nanoparticles. Density functional theory has elucidated energetically favourable multinuclear binding that further enhances capacity, while life-cycle metrics support potential industrial adoption. Complementing this, reduced graphene oxide membranes have been demonstrated to extract gold selectively at parts-per-million levels, combining spontaneous reduction on graphene domains with dispersible oxidised regions to achieve over 1,000 mg g–1 capacity and exclusive adsorption from complex mixtures. Protonation control of oxidised sites affords nearly contamination-free gold recovery, showcased in continuous flow systems processing real-world electronic waste. Additionally, two-dimensional silver(I)-organic frameworks have been fabricated to sense and capture ultra-trace gold ions down to tens of parts per billion. These frameworks combine selective uptake at vinylene-linked silver nodes with rapid kinetics and high reusability, enabling gold removal from seawater and wastewater with over 90 per cent efficiency within minutes.

Selective Recovery of Precious Metals from Aqueous Solutions publication trend

The graph below shows the total number of articles in selective recovery of precious metals from aqueous solutions across all publications each year (not limited to Nature Index journals).

Technical terms

Adsorption: Accumulation of ions or molecules at a solid–liquid interface, driven by physical or chemical interactions.

Chelation: Multidentate binding of metal ions by ligands that provide two or more coordination sites, enhancing selectivity and stability.

Reduction: Electron-transfer process that converts metal ions into their elemental or lower-valence state, often concurrent with adsorption.

Polycarbene: A polymer incorporating reactive carbene moieties that form strong covalent bonds with metal centres, serving as high-affinity adsorption sites.

Reduced graphene oxide (rGO): Graphene oxide that has undergone partial restoration of sp2 carbon networks, offering conductive domains for electron transfer and functional regions for ion binding.

Selectivity: The preferential adsorption or reaction of a target ion over competing species within a heterogeneous mixture.

References

1. Porous organic polycarbene nanotrap for efficient and selective gold stripping from electronic waste. Nature Communications (2023).
2. Highly efficient and selective extraction of gold by reduced graphene oxide. Nature Communications (2022).
3. Selective and rapid extraction of trace amount of gold from complex liquids with silver(I)-organic frameworks. Nature Communications (2022).
4. Gold Recovery from E‐Waste by Food‐Waste Amyloid Aerogels. Advanced Materials (2024).
5. 2D Electrodes From Functionalized Graphene for Rapid Electrochemical Gold Extraction and Reduction From Electronic Waste. Advanced Science (2024).