Synthesis, Characterization and Application of α, β, and γ Cyclodextrin-Conjugated Graphene Oxide for Removing Cadmium Ions from Aqueous Media

In this study, a novel and facile route for the synthesis of cyclodextrin-conjugated graphene oxide (CDs–GO) nanocomposites by esterification reaction in the presence of EDC/DMAP as catalyst, was developed. The formation of CDs–GO was successfully approved by FT-IR, SEM, TEM, TGA and BET analyses. Then competitive adsorption capacity of cadmium ion by CDs–GO composites and the impact of different empirical parameters like contact time, initial metal ion concentration, and initial pH on the adsorption process were studied. The results showed that β-CD–GO at pH 7 is suitable for removing Cd(II) with 90 % removal efficiency. Also, the adsorption capacity experiment at constant concentration of 50 ppm of Cd(II) showed that more than 50 % of Cd(II) ions could be adsorbed by γ-CD–GO reaching an equilibrium within 2 h. Therefore, the γ-CD–GO and α-CD–GO showed high adsorption capacity toward Cd2+ (222.22 mg/g) which were pointedly more than that of β-CD–GO (208.33 mg/g). Furthermore, adsorption kinetics, isotherm studies, and thermodynamic analyses were evaluated. The adsorption data exhibited excellent fit to the pseudo-second-order (R2 > 0.99) and Freundlich isotherm models.