Effect of the reduction degree of graphene oxide on the adsorption of Bisphenol A

Abstract

Graphite oxide (GO) was reduced to different reduction degrees by using hydrazine hydrate and finally to graphene using NH4OH. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption (BET), Fourier transform infrared spectroscopy (FTIR) and potentiometric titration measurements. Their adsorption performance for Bisphenol A (BPA) was evaluated taking into account pH, ionic strength, kinetics initial ion concentration and thermodynamics of adsorption. The adsorption capacities were increased with increasing the reduction degree of GO with the maximum adsorption capacity (Qmax=94.06mg/g) to be presented by Graphene that was the result of the optimum reduction degree. The adsorption followed pseudo-second order kinetics and the thermodynamic analysis indicated that it was spontaneous and endothermic. The increase in the degree of GO reduction reduced the amount of oxygen-containing functional groups on the surface of reduced samples, resulting to the increase of the π–π interaction between sorbent–adsorbate and to linear increase of adsorption capacity.