Synthesis and Photocatalytic Properties of ZnO-Volcanics Composites

Abstract

in this paper, nano-ZnO were synthesized via a sol-gel method, and ZnO-volcanics composites (ZVCs) were prepared via physical adsorption process. The morphology and structure of ZnO/ ZnO-volcanics composites (ZVCs) samples were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM).BET surface areas of the catalysts were determined by N2 adsorption (BET). According the data of XRD, the average grain size of ZnO is 15.1 nm consistent with the result observed by TEM (16.3 nm). Photocatalytic performance of ZnO and ZVCs were carried out in sprinkling photocatalytic reactor, with methylene blue (MB) as pollutants model. Decolorization rate is select as the evaluation parameters for the degradation effect. The effect of catalyst dosage, MB initial concentration, calcination temperature and pH on the degradation efficiency have been investigated. The MB degradation efficiency was 99.2% when the concentration of MB, the ZVCs, the pH and the calcination temperature were 10 mg/L, 20 g/L, and 10.03, 500 oC respectively. In the catalysts recycle experiments, the decolorization rate of MB using ZVCs is 90.2% after utilization for six times, overwhelmingly higher than that of ZnO (22.6%), indicating immobilization is efficient.