As a carbon-rich porous material, biochar has become a promising adsorbent for water remediation. It can effectively remove heavy metals, persistent organic pollutants, microplastics, and other pollutants from water. This review systematically summarizes pyrolysis as the most common preparation technique for biochar, elaborates on the advantages of its preparation techniques, and analyzes the structural and functional group rational changes of biochar after acid-base modification, oxidative modification, metal/non-metal doping, and other modifications. After modification, the material forms a rough, porous surface, with its specific surface area increased by 0.5-25 times. The adsorption capacity rises by 35%-750%, and the final pollutant removal efficiency generally exceeds 90%. It also presents favorable regeneration performance, maintaining a reuse rate of 80%-97% after 4-5 cycles. Metal/nonmetal doping is currently a prevalent and high-efficiency modification strategy. It provides a comprehensive overview of the efficient adsorption effects of biochar materials on various types of pollutants in aquatic environments, discusses the environmental safety and risk assessment of biochar, and outlines a variety of practical application processes (such as permeable reactive barriers (PRB)) that fully exploit the potential of biochar based on its characteristics in practical scenarios like groundwater. The main adsorption mechanisms of biochar-based adsorbents in the pollutant removal process, primarily including pore filling, ion exchange, electrostatic interaction, and π-π interaction, are explored. This review aims to provide a systematic theoretical basis and technical guidance for the optimal design, mechanism analysis, performance evaluation, and engineering application of biochar-based adsorption materials in the field of aquatic environment remediation.
Zhi et al. (Mon,) studied this question.