Chitosan-Based Adsorption Techniques for Heavy Metal Removal

Chitosan-based adsorption techniques exploit the unique structure and chemistry of chitosan, a linear polysaccharide rich in amino and hydroxyl groups, to capture heavy metal ions from aqueous media. The inherent cationic nature of chitosan under acidic conditions favours electrostatic attraction and chelation of metal cations, while its modifiable backbone allows for targeted functionalisation to improve selectivity, capacity and mechanical stability. Common strategies include grafting with chelating ligands, incorporation of magnetic or polymeric moieties, cross-linking to form hydrogels or beads, and blending with natural fibres or synthetic polymers to yield composite adsorbents. Adsorption mechanisms are often governed by ion exchange, complexation and pore-filling processes, with performance assessed by isotherm models and kinetic analyses. Recent advances focus on enhancing reusability, reducing cost and deploying chitosan adsorbents in continuous-flow systems. Globally, these materials offer sustainable solutions for industrial wastewater treatment, mining effluents and remediation of contaminated water bodies, addressing regulatory limits for metals such as lead, cadmium, copper and mercury.

Research from Nature Portfolio

Recent studies have reported the synthesis of a magnetic carboxymethyl chitosan adsorbent enhanced with branched polyethylenimine, achieving rapid removal of lead ions within minutes and a maximum uptake exceeding 120 mg g−1. Thermodynamic and kinetic analyses revealed a spontaneous, exothermic process best described by a pseudo-second-order model and a Langmuir–Freundlich isotherm, alongside excellent adsorbent regeneration over multiple cycles. Such work underscores the viability of functionalised chitosan frameworks for high-performance heavy metal remediation.

Chitosan-Based Adsorption Techniques for Heavy Metal Removal publication trend

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

Technical terms

Chitosan: A linear cationic biopolymer derived from chitin by deacetylation, rich in amino groups that bind metal ions.

Adsorption: The adhesion of ions or molecules from a fluid onto the surface of a solid adsorbent.

Functionalisation: Chemical modification of a polymer to introduce specific functional groups that enhance binding affinity.

Langmuir isotherm: A model describing monolayer adsorption onto a homogeneous surface with finite binding sites.

Pseudo-second-order kinetic model: A mathematical description of adsorption kinetics assuming the rate-limiting step involves chemisorption.

References

1. Rapid removal of Pb(II) from aqueous solution using branched polyethylenimine enhanced magnetic carboxymethyl chitosan optimized with response surface methodology. Scientific Reports (2017).
2. The Application of Chitosan-Based Adsorbents for the Removal of Hazardous Pollutants from Aqueous Solutions—A Review. Sustainability (2024).
3. Synthesis and Characterization of Biodegradable Poly(vinyl alcohol)-Chitosan/Cellulose Hydrogel Beads for Efficient Removal of Pb(II), Cd(II), Zn(II), and Co(II) from Water. Gels (2023).
4. Chitosan Functionalized with 2-Methylpyridine Cross-Linker Cellulose to Adsorb Pb(II) from Water. Polymers (2021).