ghodratollah shams

One of the major disadvantages of zinc oxide in aqueous solution is the light unstability of this catalyst due to the light corrosion which causes substantial reduction of photocatalytic activity of zinc oxide and application of it for environment purification. In this study, the performance of photocatalytic of UV/Silica-ZnO was compared in dye and COD removal by UV/ZnO. This study was conducted in the lab scale. The various percentages of silica nanoparticles in the combination of zinc oxides nanoparticles were fixed onto the glass by UV/Silica-ZnO process and were examined at optimum condition in the UV/ZnO process. XRD patterns of zinc oxide nanoparticles alone and accomplished by silica were conducted. X-ray diffraction, confirm that there is no impurity in nanoparticles. The different percentages of silica (5, 10 and 15%) were tested in combination with zinc oxide nanoparticles. The findings showed that the value of dye and COD removal with contact time of 90 min and 10% silica loading in UV/Silica-ZnO process were 100 % and 81%, respectively and UV/ZnO process were 66% and 44% respectively. According to the obtained results, 10% of silica, in combination with zinc oxide nanoparticles, was the best percentage. Thus, UV/Silica-ZnO process can be used as an effective method for removing dye from textile waste waters.

Effluents containing synthetic dyes are hazardous to ecological systems and public health. Methylene blue is an important chemical aromatic dye which commonly used in textile industries. Due to being aromatic، it is often toxic، carcinogenic and mutagenic. The goal of this study was to investigate the efficiency of ZnO nano particles photocatalytic process for decolorization of methylene blue by UV irradiation from synthetic textile wastewater.

In this study methylene blue photocatalytic decomposition using Ultraviolet (UV) irradiation and zinc oxide nano particles having less than 50 nm in diameter was surveyed. A batch-through Plexiglass reactor having two compartment used to conduct the experiments. Wastewater was flowed to the compartment which contains of nano ZnO stabilized glasses. UV lamps were installed at another compartment. The variables of the study included: exposure time، color concentration، light intensity، and lamp distance to the catalyst surface.

ZnO nano particles characteristics were determined by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis. Images showed that stabilizes nano particles on glass، their porosity remains in the optimal level. Optimium values for exposure time 120 minutes، color concentration 25 mg/l، light intensity 3950 μW/cm2، and distance to the catalyst surface 1 cm were achieved. At the optimal condition، methylene blue decolorization and COD removal was achieved 92. 2% and 75% respectively

Regarding the conducted experiments، the results of this studyshowed that ZnO/UV photocatalytic process has a significant efficiency in dye decolorization and COD removal. This method could be applied in the full scales.