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 beta-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 gamma-CD-GO reaching an equilibrium within 2 h. Therefore, the gamma-CD-GO and alpha-CD-GO showed high adsorption capacity toward Cd2+ (222.22 mg/g) which were pointedly more than that of beta-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 (R-2 > 0.99) and Freundlich isotherm models.

Automated summary

A novel and facile route for the synthesis of cyclodextrin-conjugated graphene oxide (CDs-GO) nanocomposites was developed in this study. The study showed that different types of CDs-GO exhibited high adsorption capacity towards Cd2+ with the adsorption process following the pseudo-second-order and Freundlich isotherm models.