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 GCOOH, 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.