Biochar-Assisted (Facilitated) Immobilization of Heavy Metals in Soil

This chapter discusses the use of biochar as a low-cost amendment for immobilizing heavy metals in soil. Heavy metal pollution in terrestrial environments is a major global concern, with common heavy metal pollutants including Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb. The chapter covers the abundance, bioavailability, and health risks of heavy metals in soil, as well as the advantages and disadvantages of using biochar over other materials for immobilization. Mechanisms of heavy metal immobilization by biochar, including polar and non-polar mechanisms such as pore filling, electrostatic attraction, hydrogen bonding, complexation, ion exchange, surface adsorption, and precipitation are also discussed in the chapter. Additionally, the chapter addresses potential risks associated with biochar application in soil and the challenges of field application. Research on biochar in soil has been limited to short-term laboratory incubations using small-scale methodologies, and the long-term impacts of biochar on soils are unclear. The chapter highlights the need for standardized production processes and feedstock selection, as well as long-term, real-scale investigations to determine the applicability of biochar for heavy metal remediation in soil.