Biochar Applications in Water Treatment and Contaminant Removal

Biochar, a carbon-rich solid derived from the thermal decomposition of biomass under oxygen-limited conditions, has emerged as a versatile agent in water treatment, offering a low-cost, sustainable route to mitigate a range of aqueous contaminants. Its efficacy derives from a highly porous structure, extensive surface area and diverse functional groups that facilitate adsorption, ion exchange, redox reactions and catalytic degradation. Tailoring of biochar by varying feedstock, pyrolysis temperature and post-treatment—such as metal or nitrogen doping, acid/base modification and magnetic nanoparticle incorporation—optimises performance against heavy metals, dyes, pharmaceuticals, organic pollutants and radionuclides. In practice, biochar has been deployed as a filter medium, in fixed-bed reactors and as part of composite hydrogel matrices, demonstrating rapid uptake kinetics and high removal capacities. Moreover, regenerability through thermal or chemical desorption strengthens its appeal for repeated cycles in industrial or municipal settings. Recent advances highlight synergistic combinations with photocatalysts and zero-valent iron to degrade recalcitrant organics via advanced oxidation. Globally, these developments signal a shift towards circular-economy water treatment technologies that convert waste biomass into high-value adsorbents, contributing to resource recovery, carbon sequestration and pollution control in regions facing acute water stress.

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Biochar Applications in Water Treatment and Contaminant Removal publication trend

The graph below shows the total number of articles in biochar applications in water treatment and contaminant removal across all publications each year (not limited to Nature Index journals).

Technical terms

Pyrolysis: Thermal decomposition of biomass in a low-oxygen environment to produce biochar, bio-oil and syngas.

Specific surface area: The total surface area per unit mass of biochar, influencing its adsorption capacity.

Surface functional groups: Reactive chemical moieties (e.g., carboxyl, hydroxyl, amino) on biochar that bind contaminants.

Adsorption isotherm: A model describing the relationship between the concentration of a solute in solution and its uptake on an adsorbent at equilibrium.

Zero-valent iron (nZVI): Nanoscale elemental iron used to impart reductive removal pathways for contaminants when combined with biochar.

Ion exchange: A process where ions in solution are swapped with ions bound to charged sites on biochar surfaces.

References

1. Biochar-based materials in environmental pollutant elimination, H2 production and CO2 capture applications. Biochar (2023).
2. Reusable magnetically-modified Enteromorpha prolifera-based biochar hydrogels: competitive removal mechanism for metal-organic dye composite contaminants. Carbon Research (2024).
3. Nitrogen-doped biochars as adsorbents for mitigation of heavy metals and organics from water: a review. Biochar (2022).