Biochar amalgamation with clay: Enhanced performance for environmental remediation

The scope of environmental remediation governed by biochar is limited to that of activated carbon due to its lower functionality and lower surface area. Incorporation of clay to biochar could possibly impart excellent sportive properties to treat a diverse range of pollutants effectively through adsorption. Clays are considered as natural pollutant scavengers for their unique characteristics such as high specific surface area, surface chemistry, and structural properties. Clay-biochar composites are generally prepared through pyrolyzing a mixture of biomass and clay or through mixing biochar and clay. Montmorillonite, bentonite, kaolinite and attapulgite clays are widely used in the synthesis of clay-biochar composites. This chapter assesses the physicochemical characteristics of the composite based biomass and clay type, clay biomass ratio, and pyrolysis condition. Pore diameter, pore-volume, surface area, and induced functional groups on the adsorbent material are the major alterations made on the biochar surface. Predominant mechanism for organic pollutant adsorption on to the composite occurs mainly through electrostatic and hydrophobic interactions, while the binding of heavy metal and nutrient ions on to the composite occurs through cationic exchange mechanism and strong covalent bonding.