Biochar: Can It Function as an Effective Detoxifier for Polluted Soils?

Soil contamination by heavy metals and organic pollutants poses a significant environmental and human health risk, exacerbated by industrialization, mining, urbanization and excessive agrochemical use. Biochar, a carbon-rich material produced via pyrolysis of organic wastes under oxygen-limited conditions, exhibits physicochemical properties such as high surface area, porosity, cation exchange capacity (CEC), and negative surface charge, enabling pollutant immobilization through adsorption, electrostatic interactions and redox mechanisms. This review evaluates the efficacy of biochar amendment as a sustainable remediation strategy for contaminated clayey and loamy soils across India and other regions worldwide and assesses its influence on soil health and pollutant dynamics. Data from multiple studies demonstrated significant reductions in heavy metal bioavailability, including copper by 45.5%, mercury up to 73.4%, cadmium between 65–87%, and lead immobilization of up to 87%. Organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and pesticides also show marked decreases upon biochar treatment. However, concerns remain regarding biochar aging, potential release of volatile organic compounds (VOCs), and long-term stability under field conditions. Further research into biochar functionalization, microbial interactions, and extended field trials is recommended to optimize its application. Overall, biochar represents a cost-effective, durable, and environmentally friendly strategy for remediating polluted soils, with interdisciplinary research and regulatory frameworks needed to maximize its benefits and minimize risks.