Preparation of ferric nitrate-graphene nanocomposite and its adsorption of arsenic(V) from simulated arsenic-containing wastewater

Ferric nitrate-graphene (FG) nanocomposites synthesized via the equivalent-volume impregnation method were used for the removal of As(V) species from simulated arsenic-containing wastewater. Effects of various factors were assessed, such as the reaction temperature, solution pH, adsorbent dosage, and reaction time. The results indicated that the As(V) removal efficiency was as high as 99%, and the concentration of arsenic-containing wastewater after FG treatment was as low as 9.4 mu g L-1 as a result of the optimal absorption capacity and maximum specific surface area (171.766 m(2)/g) of this material. The equilibrium adsorption capacity of FG for As(V) was achieved in approximately 20 min, and the maximum adsorption capacity was calculated to be 112.4 mg g(-1) by Langmuir adsorption isotherm, which was higher than that of other adsorbents such as manganese-incorporated iron(III) oxide-graphene (14.42 mg g(-1)). Moreover, the removal efficiency of As(V) can be maintained above 95% under acidic and alkaline conditions. Brunauer-Emmett-Teller analysis showed that the modified FG pore structure was regular. Based on the characterizations by X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared, the products on the surface of the used FG were Fe(OH)(3), FeAsO4, and other compounds, and As(V) was mainly removed by the formation of insoluble compounds and coprecipitation.