Agricultural Pollution Mitigation Using Iron-Enriched Biochar

Agricultural pollution remains one of the most serious environmental issues of the Anthropocene, driven by intensive farming practices that release excess nutrients, heavy metals, pesticides, and emerging contaminants into land and water ecosystems. Iron-enriched biochar (Fe-BC), a carbon-rich material produced by adding iron during or after pyrolysis, has emerged as a promising solution that combines biochar's natural physicochemical properties with iron's redox reactivity and pollutant-binding capacity. This detailed review examines recent research on Fe-BC, including its production, pollutant-reducing capabilities, performance in real-world agricultural settings, and role in sustainable farming. Fe-BC shows a remarkable ability to immobilize toxic heavy metals (such as Cd, Pb, As, Cr) through surface complexation, precipitation, and redox reactions, while also helping to retain nitrogen and phosphorus via ligand exchange and electrostatic interactions, thereby reducing eutrophication. Additionally, Fe-BC promotes the breakdown of persistent organic pollutants via Fenton-like reactions and facilitates electron transfer, thereby enhancing microbial degradation. Beyond reducing pollution, Fe-BC improves soil health, increases water retention, boosts crop yields, and contributes to climate change mitigation through carbon storage and lowered greenhouse gas emissions. However, challenges remain, including optimizing production costs, managing performance differences across various environments, evaluating potential ecological risks, establishing standardized regulations, and conducting long-term field studies. This review highlights recent advances, identifies key knowledge gaps, and suggests research priorities related to material design, environmental behavior, farming practices, and policy. With targeted investment in cross-disciplinary research and global cooperation, Fe-BC has the potential to become a key technology for sustainable agriculture, a circular economy, and environmental recovery worldwide.