Research Progress on Metal Modified Agricultural and Forestry Solid Waste Based Biochar for Remediation of Cadmium Contaminated Soil

Heavy metal Cd(Ⅱ) contamination has become a prominent soil environmental issue in China. Metal modified agricultural and forestry solid waste-based biochar is widely used in the field of soil Cd(Ⅱ) contamination remediation due to its advantages of high remediation efficiency, strong stability, and low cost. Building upon the established superiority of biochar as a chemical passivator to remediate Cd(Ⅱ) contaminated soil, this article uses chart form to classify and compare the commonly used methods and advantages and disadvantages of metal modified agricultural and forestry solid waste based biochar preparation, and describes its remediation mechanism for soil Cd pollution at the molecular level, summarize the factors influencing remediation effectiveness, analyzes the stability during the remediation process of modified biochar, and proposes feasible suggestions for current research issues. The results indicate that metal modified agricultural and forestry solid waste-based biochar exhibits superior remediation performance for soil Cd(Ⅱ) contamination. Common methods of metal modification include impregnation, reduction, and hydrothermal treatment. The remediation mechanism mainly involves precipitation, coordination, ion exchange, and electrostatic interactions. The remediation effectiveness is comprehensively influenced by factors such as dosage, pH, and reaction time. Furthermore, the stability of metal-modified agricultural and forestry solid waste-based biochar is affected by the physical, chemical, and microbial factors in the soil environment, but it demonstrates certain resistance to interference and overall stable remediation performance. Addressing current research gaps, it is recommended to enhance comprehensive exploration of preparation conditions for modified biochar, heavy metal contamination, and the long-term remediation stability of modified biochar, thereby elucidating deeper mechanism of metal modified agricultural and forestry solid waste-based biochar on heavy metal Cd(Ⅱ) polluted soil.