Thermochemical Treatment of Heavy Metal Contaminated Biomass

Thermochemical treatment leverages high‐temperature processes to stabilise or remove heavy metals from contaminated biomass while recovering energy or value‐added products. It encompasses gasification, pyrolysis and hydrothermal carbonisation, each operating under distinct temperature, pressure and oxygen conditions. Gasification converts biomass into syngas at 800–1200 °C under controlled oxygen, with volatile metals (for example Cd, Pb and Zn) largely shifting to the gas phase and less volatile species (such as Cr and Ni) remaining in the solid residues. Pyrolysis decomposes biomass in an oxygen‐limited environment, yielding biochar, bio‐oil and syngas; the distribution and speciation of metals among these phases depend on temperature, heating rate and feedstock composition. Hydrothermal carbonisation applies subcritical water (180–300 °C, high pressure) to transform wet biomass into hydrochar and an aqueous effluent, promoting the transfer of metals into the liquid phase under acidic conditions. Thermodynamic modelling and kinetic analyses underpin the predictive control of metal behaviour, guiding reactor design and operational parameters. Advances have sought to maximise metal removal efficiency, minimise corrosion and emissions, and valorise solid, liquid and gaseous streams for bioenergy, soil amendment or material synthesis. This multidisciplinary approach addresses the global challenge of remediating phytoremediation residues and industrial waste streams while producing renewable energy carriers and sustainable materials.

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Thermochemical Treatment of Heavy Metal Contaminated Biomass publication trend

The graph below shows the total number of articles in thermochemical treatment of heavy metal contaminated biomass across all publications each year (not limited to Nature Index journals).

Technical terms

Pyrolysis: Thermal decomposition of biomass in an oxygen‐limited environment producing biochar, bio‐oil and syngas.

Gasification: Partial oxidation of biomass at high temperature yielding a combustible gas mixture (syngas) and inorganic residues.

Hydrothermal carbonisation: Subcritical water treatment of wet biomass under elevated temperature and pressure producing hydrochar and an aqueous effluent.

Volatilisation: Transition of heavy metal species from the solid to the gaseous phase at elevated temperatures.

References

1. Experimental investigation of heavy metal release in entrained-flow biomass gasification. Fuel (2025).
2. Efficient Removal of Heavy Metals from Contaminated Sunflower Straw by an Acid-Assisted Hydrothermal Process. International Journal of Environmental Research and Public Health (2023).
3. Pyrolysis of industrial hemp biomass from contaminated soil phytoremediation: Kinetics, modelling transport phenomena and biochar-based metal reduction. Thermochimica Acta (2024).