Effect of different biomass species and pyrolysis temperatures on heavy metal adsorption, stability and economy of biochar

Biochar has great potential for the remediation of heavy metal pollution, but the adsorption instability and high cost of long-term soil remediation limit its industrial application. In this study, three common agricultural wastes were used to prepare biochar at temperatures ranging from 300° to 600°C and the correlative mechanisms among the preparation process, physicochemical characteristics, cost, adsorption properties, and stability of biochar were systematically studied. The results illustrated that with increasing pyrolysis temperature, the biochar yield decreased, whereas the stability and adsorption capacity increased. Economic analyses showed that biochar prepared from rice husks at 500 °C had the highest economic value (292.73 mg/$ for Pb 2+ , 84.29 mg/$ for Cu 2+ ). In addition, biochar prepared using rice husk had the highest adsorption stability due to the dominance of complexation and ion exchange. The comprehensive analysis conducted in this study provides an evaluation of the biochar preparation process and its industrial applications. • Effect of biomass species and pyrolysis temperatures on characteristics of biochar. • The relations of operating process, characteristics and adsorption mechanism. • Processing optimization from biochar stability, economy and adsorption stability. • The relations of adsorption capacity, mechanism and stability for Pb 2+ and Cu 2+ .