A review on As-contaminated soil remediation using waste biomass feedstock-based biochar and metal-modified biochar
Xiaoxian Yuan, Shifeng Li, Yang Fei, Siyuan Wang, Shiji Bie, Zhipu Wang, Hongzhen Zhang, Jian Liu, Jiabin Zhou, Xinwei Wang, Dan Liu, Feng Chen
Abstract
Arsenic (As) is a carcinogen that threatens ecosystems and human health. Due to its high adsorption, and microporosity, biochar is widely available for soil remediation. This review significantly summarizes the current status of waste biomass feedstock-based biochar and metal-modified biochar for As-contaminated soil remediation. Firstly, this paper briefly describes the sources and hazards of As in soil, and secondly, lists eleven feedstocks for preparing biochar. Agricultural, domestic, and forestry wastes provide a plentiful source for biochar preparation. Single or multi-metal modifications such as iron (Fe), manganese (Mn), and cerium (Ce) can effectively improve the Arsenite [As(III)] and arsenate [As(V)] adsorption capacity of biochar. The primary mechanisms of As removal by waste biomass feedstock-based biochar and metal-modified biochar include ion exchange, electrostatic attraction, surface complexation, redox transformation, and H-bond formation. In conclusion, this review presents an in-depth discussion on both waste biomass feedstocks and metal modification, providing constructive suggestions for the future development of biochar to remediate As-contaminated soil. • Analyze comprehensively all sources of soil As contamination. • Evaluate the hazards of As contamination on the human body. • Explore the effect of feedstock composition on biochar properties. • Illustrate the mechanism of metal modification to improve biochar performance. • Identify six challenges to remediating As-contaminated soil by biochar.