Characteristics and Applications of Biochar for Environmental Remediation: A Review

Biochar is a stabilized, recalcitrant organic carbon compound, created when biomass is heated to temperatures usually between 300 and 1000 degrees C, under low (preferably zero) oxygen concentrations. It is produced from a variety of biomass feedstock, such as agricultural residues, wood chips, manure, and municipal solid waste, through a variety of thermal treatments, among which slow pyrolysis is the most widely used due to its moderate operating conditions and optimization of biochar yields. Despite the recent introduction of the term biochar for this material, there have been several applications of charred materials in the past due to their unique properties (e.g., high specific surface area, microporosity, and sorptive capabilities). These early applications have primarily focused on the use of biochar as a soil amendment in agriculture, though other applications in environmental remediation engineering may be equally important (i.e., for soil and groundwater treatment and stormwater filter media). The objective of this review is to provide a detailed examination into the engineering properties and potential uses of biochar as an engineered material for environmental remediation. Biochar, due its highly variable and customizable surface chemistry, offers great potential in a variety of engineering applications, some of which have yet to be discovered.