Investigating the adsorption behavior and the relative distribution of Cd2+ sorption mechanisms on biochars by different feedstock

•Pig manure derived biochars (PBCs) have the best adsorption capacity for Cd2+.•The contribution of involved Cd2+ removal mechanism varied with feedstock.•Cd2+-π interaction was the predominant mechanism for Cd2+ removal on biochars.•The ash content play an important role in the removal of heavy metal by PBCs. The objective of this study was to investigate the adsorption behavior and the relative distribution of Cd2+ sorption mechanisms on biochars by different feedstock. Bamboo biochars (BBCs), corn straw biochars (CBCs) and pig manure biochars (PBCs) were prepared at 300–700 °C. Adsorption results showed PBCs have the best adsorption capacity for Cd2+, the extra adsorption capacity of PBCs mainly attributed to the precipitation or cation exchange, which played an important role in the removal of Cd2+ by PBCs. The contribution of involved Cd2+ removal mechanism varied with feedstock due to the different components and oxygen-containing functional groups. Cd2+-π interaction was the predominant mechanism for Cd2+ removal on biochars and the contribution proportion significantly decreased from 82.17% to 61.83% as the ash content increased from 9.40% to 58.08%. Results from this study may suggest that the application of PBC is a feasible strategy for removing metal contaminants from aqueous solutions.