Adsorption Techniques for Metal Ion Removal in Aqueous Systems

Adsorption offers a versatile and efficient means of extracting toxic metal ions from water by concentrating them at the interface of a solid adsorbent. Materials under study range from activated carbons and zeolites to biosorbents, polymeric hydrogels and engineered nanocomposites. Removal mechanisms include surface complexation, ion exchange and pore diffusion, all strongly influenced by solution pH, temperature and contact time. Equilibrium is typically described by isotherm models such as Langmuir or Freundlich, while uptake rates often follow pseudo-first- or pseudo-second-order kinetics. Recent work emphasises functionalisation to improve selectivity and capacity, recyclability for multiple cycles and the use of low-cost, sustainable feedstocks for global water treatment and industrial effluent remediation.

Research from Nature Portfolio

Recent studies have introduced interpenetrating composite hydrogels combining graphene oxide with biopolymeric networks. These double-network beads exhibit adsorption capacities exceeding 50 mg g−1 for manganese(II), with uptake governed by surface complexation influenced by solution pH, bead dosage and temperature. Kinetic analysis conforms to a pseudo-second-order model whereas equilibrium data align with Freundlich isotherms, indicating multilayer adsorption on heterogeneous surfaces. Notably, the material retains substantial capacity over multiple regeneration cycles, demonstrating promise for sustainable water treatment applications.

Adsorption Techniques for Metal Ion Removal in Aqueous Systems publication trend

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

Technical terms

Adsorption: Accumulation of substances at the interface between two phases, such as a solid surface and an aqueous solution.

Adsorbent: Solid material that binds and concentrates dissolved species on its surface.

Isotherm model: Mathematical relationship describing how the amount of adsorbate on the adsorbent varies with concentration at constant temperature.

Pseudo-second-order kinetics: Rate equation assuming that adsorption rate is proportional to the square of the number of unoccupied sites.

Freundlich isotherm: Empirical model describing multilayer adsorption on heterogeneous surfaces with non-uniform energies.

Hydrogel: Cross-linked polymer network capable of absorbing large volumes of water while maintaining structural integrity.

References

1. Removal of Mn (II) by Sodium Alginate/Graphene Oxide Composite Double-Network Hydrogel Beads from Aqueous Solutions. Scientific Reports (2018).
2. Adsorptive Removal of Iron and Manganese from Groundwater Samples in Ghana by Zeolite Y Synthesized from Bauxite and Kaolin. Water (2019).
3. Adsorptive Removal of Iron Using SiO2 Nanoparticles Extracted from Rice Husk Ash. Journal of Analytical Methods in Chemistry (2019).
4. Recycling of iron-rich sediment for surface modification of filters for underground water deironing. Journal of Environmental Chemical Engineering (2021).