Magnetic Adsorbents for Aqueous Contaminant Removal

Magnetic adsorbents integrate magnetic nanoparticles (commonly iron oxides such as Fe₃O₄) with high-surface-area substrates—such as activated carbon, biochar, polymeric gels or carbon nanomaterials—to achieve efficient uptake of aqueous pollutants and facile magnetic separation. Contaminants addressed range from heavy metals (Pb²⁺, Cd²⁺, As³⁺) and nutrient ions (phosphate) to organic dyes, pharmaceuticals and emerging micropollutants. Fabrication methods include co-precipitation, co-pyrolysis of biomass and waste plastics, mechanosynthesis and surface activation, yielding tailored pore structures and surface chemistries. Functional surface groups enhance selectivity and adsorption affinities, while magnetic responsiveness enables rapid recovery and regeneration. These materials support decentralised and large-scale water treatment, contributing to sustainable resource cycles by valorising waste feedstocks. Current challenges lie in controlling nanoparticle aggregation, ensuring long-term structural stability, optimising regeneration efficiency and scaling production. Advances in hybrid systems—combining adsorption with photocatalysis or membrane technologies—have broadened application scopes and demonstrated the practical potential of magnetic adsorbents in diverse environmental contexts.

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Magnetic Adsorbents for Aqueous Contaminant Removal publication trend

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

Technical terms

Adsorption isotherm: Equilibrium relationship between the concentration of an adsorbate in solution and its uptake on a solid surface at constant temperature.

Superparamagnetism: Magnetic property of nanoparticles characterised by zero remanence and coercivity, enabling particles to act like single magnetic domains and disperse readily when the field is removed.

Biochar: Carbonaceous material produced by pyrolysis of biomass, serving as a porous scaffold for magnetic nanoparticle incorporation.

Magnetic saturation (Ms): Maximum magnetisation a material attains under an external magnetic field, indicative of its separability by magnet.

Pseudo-second-order kinetics: Adsorption kinetic model assuming the rate-limiting step involves chemical adsorption through electron sharing or exchange.

Langmuir isotherm: Model describing monolayer adsorption on a homogeneous adsorbent surface, yielding parameters for maximum adsorption capacity and affinity.

References

1. Chemical activation and magnetization of carbonaceous materials fabricated from waste plastics and their evaluation for methylene blue adsorption. Environmental Science and Pollution Research (2024).
2. Application of Synthesized Biomass Bamboo Charcoal–Iron Oxide “BC/Fe” Nanocomposite Adsorbents in the Removal of Cationic Methylene Blue Dye Contaminants from Wastewater by Adsorption. Sustainability (2023).
3. Preparation of Magnetic Activated Carbon by Activation and Modification of Char Derived from Co-Pyrolysis of Lignite and Biomass and Its Adsorption of Heavy-Metal-Containing Wastewater. Minerals (2022).
4. Magnetic bio-activated carbons production using different process parameters for phosphorus removal from artificially prepared phosphorus-rich and domestic wastewater. Chemosphere (2021).
5. Mechanosynthesis as a Simple Method to Obtain a Magnetic Composite (Activated Carbon/Fe3O4) for Hyperthermia Treatment. Journal of Biomaterials and Nanobiotechnology (2016).
6. Facile Fabrication of Magnetic Poly(Vinyl Alcohol)/Activated Carbon Composite Gel for Adsorptive Removal of Dyes. Journal of Composites Science (2022).