Research Progress on the Preparation of Iron-Based Magnetic Biochar and Its Adsorption Performance for Heavy Metals in Wastewater
Biomass is the only renewable carbon resource with huge reserves and wide sources, and it is green and environmentally friendly. Under the background of 'dual carbon', the clean and efficient utilization of biomass has received increasing attention. Preparation of biochar from biomass is one of the main methods to use biomass efficiently. Biochar surfaces possess porous and aromatic structures, which exhibit good fixation effects on heavy metals in wastewater. However, biochar has shortcomings such as difficulty in recovery and non-reusability. The introduction of iron into biochar can not only enrich surface functional groups, develop pore structure, and increase specific surface area, but also endow magnetic properties, facilitating solid-liquid separation after adsorption. This paper reviews the preparation methods of iron-based magnetic biochar (MBC-Fe), summarizes the effects of different iron sources on its characteristics, and illustrates the adsorption performance and mechanisms of MBC-Fe for typical heavy metals in water. Finally, applications of MBC-Fe in the removal of heavy metal ions from wastewater are concluded, and future utilization potential in other fields is proposed. The review highlights that MBC-Fe exhibits high adsorption capacities, e.g., for Pb(II) and Cd(II), with rapid kinetics and easy separation, making it a promising adsorbent for wastewater treatment.