In this study, a graphene/biochar composite (BG composite) were synthesized by mixing the graphene (Gr) onto corn cob biomass followed by slow pyrolysis, and tested for the sorption characteristics of cadmium (Cd) from aqueous solutions. The structure and morphology analysis of the adsorbents showed that graphene was coated on the surface of biochar, resulting in a larger surface area, more functional groups, greater thermal stability, and higher removal efficiency of Cd compared to original biochar. The optimum pH values were 5.0-9.0 and the optimal dosages of BC, BG1 and BG5 were 0.5-2, 13 or 2-4 g/L for 10 mg/L Cd removal, respectively. The Cd adsorption kinetics and isotherm for BG composites can be described using the pseudo second-order model and Freundlich model. The biochar’s characteristics and adsorption experiments demonstrated that electrostatic attraction, precipitation, complexation and ion exchange are the possible Cd removal mechanisms. Results suggested that the BG composite is an efficient, economic, and environmentally friendly multifunctional adsorbent for environmental remediation.
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