The application of ZnO/SiO2 nanocomposite for the photocatalytic degradation of a textile dye in aqueous solutions in comparison with pure ZnO nanoparticles

One of the major disadvantages of the application of ZnO nanoparticles as photocatalyst in photocatalytic systems is photoinstability due to the photocorrosion under UV light irradiation resulting in the significant reduction in their photocatalytic activity. Therefore, in the present study, SiO2 nanopowders were incorporated into the ZnO nanoparticles to enhance their photocatalytic activity for the decolorization of methylene blue (MB) dye in comparison with pure ZnO/UV process. The efficiency of UV/ZnO/SiO2 process was compared with UV/ZnO process for the decolorization of MB dye and the removal of chemical oxygen demand (COD). The effect of various amounts of SiO2 (5, 10, and 15) incorporated into ZnO nanoparticles was studied. At optimal SiO2 loading of 10, the decolorization efficiency of MB and the removal of COD were obtained to be 100 and 81, respectively. However, using UV/ZnO process at the same operational conditions, the decolorization efficiency of MB and the removal of COD were 66 and 44, respectively. An initial pH of 7 and initial dye concentration of 25mg/L were chosen as optimal experimental conditions. It can be stated that the incorporation of SiO2 nanopowders into the ZnO nanoparticles would be beneficial for enhancing their photocatalytic activity

Aniline degradation using advanced oxidation process by UV/Peroxy disulfate from aqueous solution

This study is focused on removing toxic aniline from aqueous solutions using advanced oxidation process by UV/ peroxy disulfate. In this study, the effect of various parameters including pH (3-9), the level of radiation (ultraviolet 30 watt lamp, number 2-5), peroxy disulfate dose (0.02 - 0.08 mol/l) and the initial concentration (20 - 100 mg/l) at different contact times (10 - 60 min) on the efficiency of aniline removal in a laboratory reactor with UV lamps and in a batch mode, was studied. The results of this study showed that the efficiency of removing aniline decreased by increasing and decreasing pH from 5 (maximum efficiency = 66.6, at pH= 5) and also by increasing the concentration of pollutant. But by increasing the amount of radiation and peroxy disulfate dosage (0.02 to 0.08 mol/l, the process efficiencies will be 46 to 82.8 after 60 min, respectively), the efficiency increased. The efficiency of removing aniline in the combined process of UV/peroxy disulfate increased significantly by using peroxy disulfate and UV, individually (96). In the process, the efficiency of removing aniline from aqueous solution was due to the production of UV effect on Peroxy disulfate and the production of strong oxidizing radicals. Therefore, due to the high performance and low cost raw materials, this process can be used for removing resistant compounds from industrial sewages