Advancements in Biochar for Soil Remediation of Heavy Metals and/or Organic Pollutants

Summary

Biochar, a carbon-rich material made from burning plant waste with limited oxygen, can effectively clean polluted soil by trapping harmful chemicals and metals. When mixed into contaminated soil, biochar’s porous structure acts like a sponge to capture pesticides, petroleum products, and toxic metals, preventing them from spreading into groundwater or being absorbed by plants. Scientists have found that combining biochar with plants and beneficial bacteria creates an even more effective cleaning system that can remediate severely contaminated sites.

Background

Rapid industrialization has caused significant soil contamination with heavy metals and organic pollutants, which pose threats to ecosystems and human health through bioaccumulation and long-term persistence. Biochar, produced through biomass pyrolysis, has emerged as a promising remediation material due to its high specific surface area, well-developed pore structure, and abundant surface functional groups.

Objective

This review provides a comprehensive overview of biochar preparation methods, physicochemical properties, and applications in remediating soils contaminated by heavy metals and organic pollutants. It examines the interaction mechanisms between biochar and contaminants and discusses toxicity assessments and future research directions for practical deployment.

Results

Biochar demonstrates significant effectiveness in reducing pollutant mobility and bioavailability through multiple mechanisms including adsorption, ion exchange, and surface precipitation. Studies show 24.99% average PAH reduction, up to 85% PCB removal with biochar-plant combinations, and 41.7-80.1% reduction in arsenic bioavailability depending on modification and application rates.

Conclusion

Biochar is a cost-effective, durable soil amendment capable of remediating multiple contaminant types simultaneously. Modified biochar with iron compounds shows enhanced performance for anionic metals, while unmodified biochar is effective for organic pollutants. Combined biochar-plant-microbial approaches offer promising strategies for large-scale soil remediation applications.
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