[Preparation of Iron-modified Biochar and Its Application in Arsenic Contaminated Soil Remediation]

Biochar has a range of advantages including large porosity, high specific surface area, and strong adsorption capacity. It has been widely used in environmental pollution remediation, soil improvement, and carbon sequestration and emission reduction. Arsenic (As) is a highly toxic pollutant widely distributed throughout the soil. In typical surface soils, the most common forms of As are arsenite (AsO₃^3-) and arsenate (AsO₄^3-). Since most biochar surfaces are negatively charged, the adsorption efficiency of biochar to arsenic is usually low, and the biochar material needs to be modified to enhance its As adsorption performance. Iron-based materials, such as zero valent iron and iron oxide, are excellent As adsorption materials with wide environmental sources. They can be loaded to biochar to form iron-modified biochar via precipitation, pyrolysis, ball-milling, and micro-biological methods. The combined advantages of the iron-modified biochar will expand the application of biochar materials in environmental remediation. Based on a systematic analysis of the literature on iron-modified biochar in recent years, this study reviewed the common preparation methods of iron-modified biochars; analyzed biochar substrates, iron-modified biochar, and their synergistic mechanisms on As adsorption; and briefly expounded the application status of iron-modified biochar in soil pollution remediation. The prospects of the future research direction of iron-modified biochar were put forward as a reference for the large-scale application of biochar materials in the future.