Functionalized graphene nanosheets as absorbent for copper (II) removal from water.

Functionalized graphene nanosheets (FGNs) with high surface area and various functional groups were prepared by oxidation method. The characteristics of FGNs were studied by nitrogen adsorption using the Brunauer-Emmett-Teller (BET) method, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersion spectrum (EDS), and atomic force microscopy (AFM). The specific surface area of obtained FGNs was measured as 834.06 m g, which was 20-40% higher than graphene nanosheets (GNs) before oxidation. An abundance of oxygen-containing functional groups, such as carboxyl, hydroxyl and epoxy groups, was grafted on the edge and surface of GNs. Moreover, FGNs demonstrated excellent adsorption and desorption performance when used as absorbent to remove Cu (II) from aqueous solution. The removal percentage could reach 96% within 1 h and remain 72% after 5 adsorption-desorption cycles. Adsorption process and mechanism were elucidated by kinetics models and isotherm models. The results showed FGNs has a great potential to be an adsorbent for removal copper ions from water.