A Comparative Study of Photocatalytic Activity of ZnO/activated Carbon Nanocomposites Prepared by Solid-state and Conventional Precipitation Methods

ZnO/activated carbon nanocomposites (ZnO/ACns) were synthesized by applying two different solid-state and precipitation methods. Precipitation method was initiated with zinc chloride and sodium hydroxide as starting materials in the presence of activated carbon. The synthesized sample was calcined at 250 °C for 1 h. The preparation of nanocomposite by solid-state method was accomplished by heating a mixture of ZnCl2 and activated carbon at 250 °C for 1 h, which led to the formation of ZnO particles on the surface. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Photocatalytic activity of these ZnO/acnes was evaluated by the degradation of methyl orange under UV-light radiation. The SEM images of samples show that the agglomerations of particles are much less in solid-state method prepared samples.  The results of EDS indicate that the ratio of Zn/C in the pure activated carbon and nanocomposites prepared by solid-state and precipitation methods were 0, 1.7 and 3.7 % (W/W), respectively. The XRD of the samples clearly shows that the sample prepared by the above routes has ZnO structures. Finally, ZnO/ACn prepared by the solid-state method demonstrated better photocatalytic efficiency against methyl orange dye than composites made by precipitation method.