چكيده به لاتين
In recent years, the development of cities and the daily expansion of industries have resulted in the release of a wide variety of organic pollutants such as dye to the water and posed major challenges for the mankind such as the reduction of drinking water and so on. Among the most effective methods for removing pollutants and wastewater treatment that have received much attention in recent years, it is the Photocatalytic degradation of pollutants using TiO2 photocatalyst which matters so much due to its high ability to remove a wide range of pollutants and being low cost and environmentally friendly. However, this process suffers from major obstacles and limitations such as inactivity under the visible light, the low adsorption capacity of organic compounds on the photocatalyst surface, and so on. In this study TiO2/SiO2 photocatalyst is used in order to remove RhB as a sample pollutant under visible light (150 W tungsten lamp) and in the laboratory environment. To improve the photocatalytic activity, tungsten and bismuth oxides were used to dope the Titania-Silica and it was observed that this action causes an increase in the photocatalytic activity which this is due to appropriate electron transfers in the presence of visible light and the reduction of electron-hole recombination. In order to remove another obstacle to the photocatalytic process, which is the low adsorption capacity of organic compounds on the surface, two different surface modification methods called silylation and fluorination were used separately. Using FTIR, N2 adsorption- desorption, FE-SEM, EDX, TGA and the contact angle of the synthesized catalysts were investigated. It was found that both surface modification methods replaced the surface hydroxyl groups without altering the volume and diameter of the pores and maintaining the mesoporous structure and texture of photocatalysts, by silyl and fluoride groups, respectively, which this causes the surface to be hydrophobic (in both methods), shifts pzc toward low pH and creates a negative charge on the surface and so on (in fluorination). All of these increase the adsorption capacity of RhB by photocatalysts and consequently, it improves the RhB removal process. This was proved by photocatalytic degradation tests. After only 30 minutes of visible light irradiation (90 minutes after the start of the process), the silylated and fluorinated photocatalysts removed 92.11% and 92.68% of the RhB, respectively. While for the unmodified photocatalyst, this rate is 79.33%.
