A comparison of Photocatalytic silica-zinc oxide and zinc Oxide processes for the removal of dye and COD in the synthetic wastewater

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.