β–cyclodextrin functionalized biochars as novel sorbents for high-performance of Pb2+ removal

The aim of this study was to synthesize the functionalized biochars with β–cyclodextrin (β–CD), compare the two kinds of adsorption capability, and try to explore the possible mechanism for the adsorption Pb2+ by β–CD functionalized rice straw and palm biochars in the aquatic environment. The performance of the functionalized biochars was matched against the activated and raw biochars. Rice straw biochar loaded with β–CD performed better than functionalized palm biochar with the adsorption capabilities of 130.60 mg/g and 90.30 mg/g at Pb2+ concentration of 3000 mg/L and 2000 mg/L, respectively. Maximum adsorption capability of functionalized rice straw and palm biochars from the Langmuir isotherms were all fitted out to be 131.24 mg/g and 118.08 mg/g for Pb2+. Kinetics and thermodynamics are combined to investigate the Pb2+ removal by the two functionalized biochars, e.g, Pb2+ is mainly removed by chemical process for functionalized palm biochar, whereas by both physical and chemical factors for functionalized rice straw biochar.