Advances in heavy metal wastewater treatment with biochar adsorption

Abstract In recent years there has been a growing interest in biochar as an efficient adsorbent for heavy metal wastewater treatment because of its unique physicochemical properties and broad applicability. Biochar, produced through the pyrolysis of waste biomass, exhibits a well developed pore structure, a high specific surface area, and abundant surface functional groups, which collectively confer its high capacity for the adsorption of heavy metals. This review summarizes the current state of knowledge on biochar preparation methods, properties, and adsorption mechanisms for heavy metal removal. It highlights the impact of biochar characteristics such as pore‐size distribution, surface functional groups, and pyrolysis temperature, on its adsorption performance. It also examines the influence of solution conditions, including pH, temperature, and ionic strength, on biochar adsorption. The review explores the synergistic effects of biochar with other wastewater treatment technologies, such as anaerobic digestion and membrane technology, to enhance treatment efficiency. Despite significant progress, challenges remain in optimizing biochar adsorption capacity, regeneration, and recycling. This study provides comprehensive insights into the potential and limitations of biochar in heavy metal wastewater treatment; it identifies knowledge gaps and outlines future research directions. By elucidating the relationship between the properties of biochar and its performance in heavy metal removal, the aim of this review is to guide the selection of appropriate biochar for various wastewater treatment applications.