Preparation, Characterization and Photo Catalytic Activity of Zinc Oxide\Silica Gel Composites

In this study, synthesis and characterization of ZnO/silica gel photo catalyst for degradation of the methyl orange from wastewaters were investigated. For this purpose, ZnO/Silica composite was prepared by immersing silica gel in the zinc chloride molten bath at a temperature of 560 ⁰C for 20, 40, 60 and 90 minutes. For synthesis of these composites, no reducing agent or chemical agent was used except zinc chloride. In this method, synthesis of nanoparticles and their immobilization on the substrate was done instantly. The synthesized composites were characterized by XRD, SEM and DRS analysis. The scanning electron microscope (SEM) pictures showed that ZnO nanoparticles were formed on the silica gel surface as a thin layer by using a molten salt process. The results indicate the formation of ZnO layer on the silica surface in the form of flat films, which at longer times the film thickness increases while after 60 minutes produced a number of visible nanoparticles. XRD patterns indicated amorphous structure of silica gel and the crystalline structure of ZnO nanoparticles . In addition, the stability of synthetized nanocomposites was confirmed by water leaching test. Finally, the photocatalytic activity of the composites was assayed against methyl orange dye. The decolorization efficiency of prepared composites of 20, 40 and 60 min was close together and about 39.9, 40.6 and 41.3%, respectively.