Preparation Of Graphene Oxide And Graphene Nanomaterials And Their Application In Heavy Metal Ions Removal

Carbon family has recently attracted increasing attention for its especial electronic and mechanical properties, especially graphene oxide and graphene. Due to their one-atom thickness, the2D planar structure material has several excellent attributes, such as large theoretical specific surface area of about2630m2g-1.Moreover, the surface functionalization of carbon materials can be adjusted via chemical modification for various applications.In this study, graphene oxide (GO) has been prepared from graphite by modified Hummers method and graphene synthesized by chemical method (GC) has been successfully synthesized by the oxidation-reduction process. The obtained sample are characterized by XRD, Raman spectroscopy and Atomic Force Measurement. It is found that the D (near1333cm-1) band undergo significant changes in Raman spectroscopy due to the carbon rupture during the oxidation reaction. The intermediate oxidized graphite showed the very strong001peak at10.6°in the XRD spectroscopy indicates the existence of graphene oxide. Moreover, an atomic force microscopy image shows that graphene contains about13-18layers. The disappearance of the001peak at10.6°and the reoccurrence of the002peak at24°in the XRD spectroscopy demonstrates the successfully preparation of graphene. The result of the Raman spectroscopy and the transmission electron microscope image also prove it. Besides, the specific surface area of graphene is530.07m2g-1.In addition, we have investigated Cd2+adsorption dynamically and thermodynamically onto five kinds of carbon materials, carbon nanotubes (CNTs), active carbon (AC), graphene oxide (GO), graphene synthesized by chemical method (GC), graphene synthesized by physical method (GP). Adsorption kinetics and isotherms have been investigated. The adsorption equilibrium data are well described by Langmuir equation, the Freundlich equation, and the Three-parameter equation. It is found that this adsorption belongs to physical adsorption enhanced by a chemical effect and is able to reach adsorption equilibrium quickly. The adsorption property of GP is obviously better (138.6mg/g) than any other materials. The competitive adsorption studies show that the adsorptive capacity order of Cd2+is GP>AC>GO>CNTs>GC. Furthermore, adsorption temperature has effect on Cd2+adsorption. With CNTs as adsorbent, the Cd2+adsorption amount slightly increases with the decrease of temperature. So, the adsorption processes of Cd2+onto the surface of CNTs are exothermic. Meanwhile, the adsorption processes over other carbon materials are endothermic. It is believed that carbon materials as adsorbents for heavy metal ion removal in environment may possess a vast range of application prospect.