Removal of cadmium ion from waste water using carboxylated nanoporous graphene (G-COOH)

Abstract

Carboxylated nanoporous graphene (G-COOH), an excellent adsorbent, were successfully synthesized by an in chemical vapor deposition method and used for the removal of Cd (II) ion from aqueous solution. The synthesized G-COOH were characterized by SEM, XRD and FT-IR techniques. Various operational parameters such as pH, initial Cd (II) ion concentration and contact time in batch systems were investigated on the use of G-COOH. Equilibrium data obtained have been fitted to the Langmuir and Freundlich adsorption isotherms. Langmuir isotherm best fits the experimental results. The sorption kinetics exhibited the best fit to the pseudo-second order equation and the equilibrium followed Langmuir isotherm model. The maximum sorption capacity qmax in Langmuir isotherm of Cd (II) ion 3.37 mg/g showed onto G-COOH, Isotherms had also been used to obtain the thermodynamic parameters such ΔG0 indicates the feasibility and spontaneity of the adsorption process. The positive ΔH0 suggests the endothermal nature of the adsorption. The positive values of ΔS0 reflects the affinity of G-COOH towards Cd (II) ion. The results indicated that Cd (II) ion adsorption onto G-COOH composite might be a physical adsorption.