Biosorption of Heavy Metals Using Algal Biomass

Biosorption employs the natural affinity of algal biomass—both living and non-living—to sequester heavy metal ions from aqueous environments through mechanisms such as ion exchange, complexation and micro-precipitation. Algal cell walls are rich in functional groups (carboxyl, hydroxyl, sulphate and phosphate) that bind metal cations, enabling rapid removal even at low concentrations. This approach offers an inexpensive, eco-friendly alternative to conventional treatments, with potential for metal recovery and biomass reuse. Research has demonstrated that biosorbent performance is influenced by parameters including pH, temperature, contact time and biomass preparation. Scalable applications span industrial effluent treatment, acid mine drainage remediation and agricultural wastewater management. The integration of characterisation techniques (FTIR, SEM, EDS) with mathematical modelling (Langmuir, Freundlich, kinetic and thermodynamic models) underpins the design of optimised processes suitable for deployment in diverse geographic and economic contexts.

Research from Nature Portfolio

Recent investigations have focused on the optimisation and characterisation of marine and microalgal biomass to enhance biosorption capacity for priority metals. A seminal study evaluated the red alga Gelidium amansii as a biosorbent for lead(II), employing factorial design and central composite methods to identify optimal conditions (200 mg L⁻¹ initial Pb²⁺, pH 4.5, 45 °C) that yielded 100 % removal. Functional group analysis via FTIR and surface imaging by SEM confirmed the involvement of carbonyl, phosphate and phenolic moieties. Immobilisation of the biomass further facilitated reuse without loss of efficiency. Another pivotal work applied a hybrid response surface methodology–crow search algorithm to Chlorella kessleri, achieving over 99 % lead removal at pH 6.3 and 27.7 °C. Modelling indicated that the process obeys pseudo-second-order kinetics and Langmuir isotherm behaviour, with successful simultaneous removal of multiple heavy metals.

Biosorption of Heavy Metals Using Algal Biomass publication trend

The graph below shows the total number of articles in biosorption of heavy metals using algal biomass across all publications each year (not limited to Nature Index journals).

Technical terms

Biosorption: Passive binding of metal ions to non-living biomass via surface functional groups.

Ion exchange: Replacement of light cations (e.g. Na⁺, Ca²⁺) on biomass with target heavy metal ions.

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

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

FTIR (Fourier-transform infrared spectroscopy): Technique for identifying chemical bonds and functional groups on biosorbent surfaces.

SEM (Scanning electron microscopy): Imaging method for visualising biomass morphology and surface changes after metal uptake.

References

1. Metal biosorption onto non-living algae: a critical review on metal recovery from wastewater. Green Chemistry (2023).
2. A comprehensive review on microalgae-driven heavy metals removal from industrial wastewater using living and nonliving microalgae. Journal of Hazardous Materials Advances (2024).
3. The Utilization of Algae and Seaweed Biomass for Bioremediation of Heavy Metal-Contaminated Wastewater. Molecules (2022).
4. Biosorption optimization, characterization, immobilization and application of Gelidium amansii biomass for complete Pb2+ removal from aqueous solutions. Scientific Reports (2018).
5. Experimental study and parameters optimization of microalgae based heavy metals removal process using a hybrid response surface methodology-crow search algorithm. Scientific Reports (2020).