Adsorption Mechanisms of Cyclodextrin-Based Materials in Water Treatment

Cyclodextrin-based adsorbents exploit the unique truncated-cone architecture of cyclodextrin units to capture and remove a wide spectrum of waterborne contaminants via surface adsorption and inclusion complexation. The hydrophobic cavity of cyclodextrins hosts organic micropollutants through non-covalent host–guest interactions, while external functional groups and crosslinkers impart selectivity for charged species or metals. Adsorption proceeds through a combination of physical sorption, driven by van der Waals and hydrophobic forces, and chemisorption, involving specific bonding or complexation with active sites. Pore structure and surface area control mass transfer rates, with diffusion through interstitial networks often dictating overall kinetics. Tailored polymer matrices—incorporating magnetic fillers, chelating moieties or polysaccharide backbones—enhance capacity, regeneration and practical applicability, addressing global needs for efficient, reusable and low-cost water treatment technologies.

Research from Nature Portfolio

A green one-pot synthesis of a chitosan-EDTA-β-cyclodextrin trifunctional adsorbent demonstrates simultaneous removal of heavy metals and diverse organic micropollutants at environmentally relevant concentrations. The material combines EDTA units for strong metal chelation with cyclodextrin cavities for host–guest inclusion, achieving monolayer capacities exceeding 0.8 mmol g⁻¹ for Pb(II) and Cd(II) and effective uptake of bisphenol S, ciprofloxacin and other pharmaceuticals. Thorough characterisation confirms a stable network offering rapid kinetics, high selectivity and recyclability without significant loss of performance after multiple cycles.

Adsorption Mechanisms of Cyclodextrin-Based Materials in Water Treatment publication trend

The graph below shows the total number of articles in adsorption mechanisms of cyclodextrin-based materials in water treatment across all publications each year (not limited to Nature Index journals).

Technical terms

Cyclodextrin: Cyclic oligosaccharide with a hydrophobic central cavity that encapsulates small organic molecules through non-covalent interactions.

Host–guest inclusion complexation: Non-covalent binding process in which a guest molecule is lodged within the cavity of a host molecule, such as a cyclodextrin unit.

Langmuir isotherm: Model describing monolayer adsorption on a homogeneous surface with finite, identical sites and no interactions between adsorbed molecules.

Pseudo-second-order kinetic model: Description of adsorption kinetics assuming chemisorption as the rate-limiting step, proportional to the square of unoccupied sites.

Crosslinking agent: Chemical reagent that connects polymer chains to form a three-dimensional network, enhancing mechanical stability and controlling porosity.

References

1. β -Cyclodextrin polymer/zinc ferrite nanocomposite: Synthesis, characterization, and adsorption application for the removal of malachite green and Congo red. Journal of Hazardous Materials Advances (2023).
2. One-pot synthesis of trifunctional chitosan-EDTA-β-cyclodextrin polymer for simultaneous removal of metals and organic micropollutants. Scientific Reports (2017).
3. β-Cyclodextrin-Polyacrylamide Hydrogel for Removal of Organic Micropollutants from Water. Molecules (2021).