Recently, biochar has emerged as a promising option for environmentally friendly remediation due to its cost-effectiveness, extensive surface area, porosity, and exceptional electrical conductivity. Biochar-based advanced oxidation procedures (BC-AOPs) have gained popularity as an effective approach to breaking down organic pollutants in aqueous environments. It is commonly recognized that the main reactive locations within BC-AOPs consist of functional groups found on biochar, which encompass oxygen-containing groups (OCGs), imperfections, and persistent free radicals (PFRs). Additionally, the existence of metallic components supported on biochar and foreign atoms doped into it profoundly impacts the catalytic mechanism. These components not only modify the fundamental qualities of biochar but also serve as reactive sites. Consequently, this paper offers a comprehensive review of the raw materials, preparation techniques, modification approaches, and composite catalyst preparation within the biochar catalytic system. Special attention is given to explaining the modifications in biochar properties and their impacts on catalytic activity. This paper highlights degradation mechanisms, specifically pathways that include radical and non-radical processes. Additionally, it thoroughly examines the importance of active sites as catalysts and the basic catalytic mechanism of BC-AOPs. Finally, the potential and future directions of environmental remediation using biochar catalysts and advanced oxidation processes (AOPs) are discussed. Moreover, suggestions for future advancements in BC-AOPs are provided to facilitate further development.

The background value of iron in red soil is superior, primarily absorbed and homogeneously encapsulated in harvested biomass. However, this property on the high-value utilization of bionic iron-encapsulated biomass remains unknown. In this study, special biochar (Fe@BC) was obtained from this kind of biomass by one-step pyrolysis method, which was further used to activate peroxydisulfate (PDS) and degrade 2,4-dichlorophenol (2,4-DCP). The results showed that Fe₃O₄ was formed and homogeneously embedded in biochar at 500^oC. Comparing to catalysts prepared by impregnation pyrolysis (Fe/BC), Fe@BC exhibited excellent degradation performance (90.9%, k = 0.0037 min⁻¹) for 2,4-DCP. According to the free radicals quenching studies, hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻) were the dominant reactive oxygen species (ROS) in Fe@BC/PDS system. Importantly, a PDS adsorption model was established, and the electron transport and PDS activation in the core-shell structure were demonstrated by DFT calculations. Therefore, this study could supply a high-performance catalyst and significant implications for high-value biomass utilization in red soil.