Selective Adsorption Techniques for Precious Metal Recovery

Selective adsorption represents a pivotal approach for reclaiming valuable metals such as platinum, palladium and rhodium from diverse aqueous wastes. Techniques centre on engineered adsorbents bearing specific ligands or imprinted sites that preferentially bind target ions in complex matrices. Functionalisation of polymer supports, sculpting of mesoporous structures, and integration of biological biosorbents have yielded materials with enhanced capacity, selectivity and reusability. Control over surface chemistry, pore architecture and binding mechanisms underpins efficient recovery, while isotherm and kinetic modelling guide process optimisation. Global demand for secondary sources is driving innovation in adsorbent design, from crown-ether-grafted resins to ion-imprinted membranes and biopolymeric constructs, offering sustainable routes for the circular economy of precious metals.

Research from Nature Portfolio

Recent studies have introduced a biopolymer-based adsorbent in which chitosan is impregnated with dibenzo-18-crown-6 ether via a solvent-impregnated resin method, demonstrating high uptake of platinum group metals from chloride media. Equilibrium and kinetic analyses, applying models such as Langmuir isotherms and pseudo-second-order kinetics, confirm chemisorption-dominated interactions and maximum capacities competitive with conventional sorbents. Another innovation employs extractant-impregnated resins containing a pincer-type ligand embedded in a polymer matrix, delivering over 98 per cent selectivity for palladium in mixed-metal leachates. This system exhibits exceptional reusability and spontaneous, endothermic sorption behaviour, with sorption–desorption cycling retaining efficiency for more than twenty iterations.

Selective Adsorption Techniques for Precious Metal Recovery publication trend

The graph below shows the total number of articles in selective adsorption techniques for precious metal recovery across all publications each year (not limited to Nature Index journals).

Technical terms

Adsorption isotherm: A curve describing the relationship between the amount of substance adsorbed per unit mass of adsorbent and its concentration in solution at equilibrium.

Pseudo-second-order kinetics: A kinetic model that assumes the rate of occupation of adsorption sites is proportional to the square of the number of unoccupied sites, often indicating chemisorption.

Ion-imprinting: A synthesis technique that creates templated binding sites within a polymer network, tailored for the selective recognition of a target ion.

Functionalisation: The process of chemically modifying a material’s surface or structure to introduce specific reactive groups or ligands.

Chelating agent: A molecule capable of forming multiple bonds to a single metal ion, stabilising it through ring-like coordination complexes.

Biosorption: The passive uptake of metal ions by biological materials, such as microbial cells or biopolymers, via physicochemical interactions.

References

1. Precious metals recovery from aqueous solutions using a new adsorbent material. Scientific Reports (2021).
2. Environmentally friendly Pd(II) recovery from spent automotive catalysts using resins impregnated with a pincer-type extractant. Scientific Reports (2021).
3. Evaluation of Performance of Functionalized Amberlite XAD7 with Dibenzo-18-Crown Ether-6 for Palladium Recovery. Materials (2021).
4. Removal of Platinum and Palladium from Wastewater by Means of Biosorption on Fungi Aspergillus sp. and Yeast Saccharomyces sp.. Water (2019).
5. A Comparison of Palladium Sorption Using Polyethylenimine Impregnated Alginate-Based and Carrageenan-Based Algal Beads. Applied Sciences (2018).