Waste-to-value conversion: A comprehensive review on biochar production, modification, and remediation potential

Over recent years, biochar has attracted significant attention from researchers due to its carbon-rich composition and unique physicochemical properties. Organic waste materials, including agricultural residues, domestic biomass, municipal waste, and other organic solid wastes, serve as the primary feedstocks for biochar production. High carbon content, large surface area, excellent cation exchange capacity, and structural stability are among the key characteristics that make biochar a valuable material for environmental applications. This review focuses on various organic waste feedstocks suitable for biochar production. It provides a comprehensive overview of different biochar production methods and discusses how these processes influence the structural and functional properties of the resulting biochar. While plant-based biomass is the most commonly used feedstock, forest residues and other organic wastes also offer significant potential for biochar production and utilization. Furthermore, various physical and chemical activation techniques employed to enhance the surface properties, porosity, and adsorption performance of biochar are critically reviewed. The applications of biochar in environmental remediation, particularly in soil remediation, wastewater treatment, and gas purification, are also comprehensively discussed. Overall, this review highlights the growing importance of biochar in environmental remediation and provides an overview of activation strategies that optimize its performance for specific applications.