Radiation-Grafted Adsorbents for Aqueous Contaminant Removal

Radiation-grafted adsorbents represent a class of polymeric materials in which energetic particles—typically γ-rays or electron beams—are employed to generate active sites on inert substrates, enabling the subsequent covalent attachment of functional monomers. This strategy permits precise control over graft density and distribution of reactive chains, yielding adsorbents with tailored affinities for a wide range of aqueous pollutants, including heavy metals, dyes and phenolic compounds. By selecting monomers bearing chelating, ion-exchange or hydrophobic moieties, researchers have created robust films, fibres and non-woven fabrics that combine mechanical integrity with high adsorption capacity. Key advantages include the elimination of chemical initiators, minimal residual impurities and the potential for in situ sterilisation. Recent developments have focused on improving graft uniformity, maximising accessible surface area and integrating nanofillers to enhance selectivity. The global significance of radiation-grafted adsorbents lies in their adaptability to local water-treatment needs, low environmental footprint and compatibility with continuous-flow processes. Advances in grafting methodologies and adsorbent regeneration bring these materials closer to industrial deployment for remediation of industrial effluents, mining runoff and municipal wastewater.

Research from Nature Portfolio

In one foundational study, polypropylene grafted with maleic anhydride was blended with chitosan and montmorillonite via twin-screw melt extrusion to produce nanocomposites for lead removal. Characterisation by X-ray diffraction and electron microscopy confirmed homogeneous dispersion of clay and biopolymer phases, while adsorption tests demonstrated over 90 % Pb(II) uptake following Langmuir behaviour and pseudo-second-order kinetics. This work underscores the synergy between radiation-grafted compatibilisers and bio-based components to achieve superabsorbent performance. In a complementary fibre-based approach, polyamide-6 was pre-irradiation grafted with glycidyl methacrylate then functionalised with trimethylamine to yield a porous fibrous network. Surface analyses revealed high epoxy conversion and abundant quaternary ammonium sites. The modified fibres exhibited a maximum p-nitrophenol capacity of 176 mg g⁻¹, fitting a Redlich–Peterson isotherm and showing stable regeneration over multiple cycles. This study highlights the versatility of electron-beam methods for producing reusable adsorbents targeting neutral and ionic organic contaminants.

Radiation-Grafted Adsorbents for Aqueous Contaminant Removal publication trend

The graph below shows the total number of articles in radiation-grafted adsorbents for aqueous contaminant removal across all publications each year (not limited to Nature Index journals).

Technical terms

Radiation-induced graft polymerization: A technique using high-energy radiation to generate polymer radicals on a substrate, enabling covalent attachment of monomers without chemical initiators.

Degree of grafting (DG): The mass increase of a substrate expressed as a percentage, reflecting the extent of monomer incorporation.

Adsorption isotherm: A mathematical model describing the equilibrium distribution of adsorbate between the liquid phase and the adsorbent surface.

Ion-exchange groups: Functional sites—such as quaternary ammonium or carboxylate moieties—that selectively bind counter-ions from solution.

Pre-irradiation method: A grafting approach in which the substrate is first exposed to radiation and then contacted with monomer, enhancing control over radical generation and graft uniformity.

References

1. Radiation-Grafting on Polypropylene Copolymer Membranes for Using in Cadmium Adsorption. Polymers (2023).
2. Melt processing of polypropylene-grafted-maleic anhydride/Chitosan polymer blend functionalized with montmorillonite for the removal of lead ions from aqueous solutions. Scientific Reports (2020).
3. Trimethylamine functionalized radiation-induced grafted polyamide 6 fibers for p-nitrophenol adsorption. Scientific Reports (2021).
4. Synthesis of Amidoxime Adsorbent by Radiation-Induced Grafting of Acrylonitrile/Acrylic Acid on Polyethylene Film and Its Application in Pb Removal. Polymers (2022).