Biosorption Techniques for Phosphate and Heavy Metal Removal in Aqueous Systems

Biosorption harnesses the natural affinity of biological materials to sequester phosphate and heavy metal ions from water, offering a sustainable alternative to conventional chemical treatments. A diverse array of sorbents—including crustacean and mollusc shells, chitin and chitosan derivatives, agricultural residues and engineered biocomposites—exhibits high surface area and functional groups capable of electrostatic interaction, ion exchange and complexation. Key operational parameters such as pH, contact time, sorbent dosage and initial contaminant concentration profoundly influence performance. Equilibrium data are typically described by Langmuir or Freundlich isotherms, while kinetic studies often conform to pseudo-first- or pseudo-second-order models. Advances in material modification, for instance through low-temperature activation, polymer cross-linking and nanoparticle grafting, have enhanced adsorption capacities and selectivities. These developments not only address eutrophication driven by excess phosphate but also mitigate toxic metal contamination—such as lead, cadmium, copper and chromium—in industrial and stormwater contexts. Integration into full-scale processes demands attention to sorbent regeneration, mechanical stability and cost-efficiency, yet the potential for circular-economy valorisation of biowaste underpins the global significance of biosorption strategies.

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Biosorption Techniques for Phosphate and Heavy Metal Removal in Aqueous Systems publication trend

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

Technical terms

Biosorption: Passive binding of ions or molecules to biological materials via physical and chemical interactions.

Adsorption isotherm: Mathematical relationship describing equilibrium distribution of a solute between solid sorbent and liquid phase.

Langmuir isotherm: Model assuming monolayer adsorption on a finite number of uniform sites.

Freundlich isotherm: Empirical model depicting adsorption on heterogeneous surfaces.

Pseudo-second-order model: Kinetic expression assuming rate of adsorption is proportional to the square of the number of unoccupied sites.

Ion exchange: Mechanism whereby ions in solution are replaced by counter-ions on the sorbent surface.

Functional groups: Specific atomic arrangements (e.g. –NH2, –CO3) on a sorbent surface responsible for binding interactions.

References

1. Adsorption mechanism of shell powders on heavy metal ions Pb2+/Cd2+ and the purification efficiency for contaminated soils. Frontiers in Earth Science (2023).
2. Preparation of PVA/waste oyster shell powder composite as an efficient adsorbent of heavy metals from wastewater. Heliyon (2022).
3. Synthesis optimisation and characterisation of chitosan-calcite adsorbent from fishery-food waste for phosphorus removal. Environmental Science and Pollution Research (2020).