Adsorption properties of graphene oxide/chitosan microspheres for removal of Cr(VI) from aqueous solutions

The graphene oxide (GO) and graphene oxide/chitosan micro spheres (GOCS) for removal of hexavalent chromium were prepared and characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The adsorption behavior of the GOCS and chitosan (CS) micro spheres for Cr (VI) was studied, and the effects of solution pH, adsorption time, and initial metal ion concentration on adsorption capacity of the adsorbent were also investigated. The adsorption capacities of GOCS and CS were found to be 197.6 mg/g and 129.9 mg/g, respectively. The characteristics of the adsorption process were evaluated by using the Langmuir and Freundlich isotherm models. The adsorption processes fit better with the Langmuir model. The adsorption of Cr (VI) on GOCS was a typical mono molecular layer adsorption. The pseudo-first-order and pseudo-second-order kinetic models were employed to describe the kinetic processes, and the results indicated that the adsorption of Cr (VI) followed a second-order type reaction kinetics.