Study On The Preparation And Degradation Of Chlorophenols By Ag/TiO₂ Nanoparticle Catalyst

In this paper, the preparation of Ag/TiO₂ nanoparticle catalyst and the degradation of chlorinated phenol were studied, which content have been divided into four parts.In first part, it systematically expounds the properties, source and environmental hazards of the chlorinated phenols. Secondly, the four main preparation methods o f modified TiO₂ catalyst were discussed. Based on many aspects, in this paper, the preparation method of the catalyst was determined by the Sol-Gel method.Finally, the development status and application prospect of Ag/TiO₂ nanoparticle catalyst for the degradation of chlorinated phenols were summarized, and then the significance of this paper has been proved.In second part, based on the Sol-Gel method, selection the four butyl titanate as raw material, glacial acetic acid as inhibitor, and the Ag/TiO 2 nanoparticle photocatalyst with different ratio was prepared by the single element Ag doped. The temperature as a single variable, according to the degradation of 2,4-dichlorophenol and pentachlorophenol sodium to explore their photocatalytic properties. In addition, the shape and structure have been characterized and discussed by the X-ray diffraction（XRD） and the scanning electron microscope（SEM）.The results show that in this project should select the best calcination temperature was 450 oC.In third part, selection the Phenol, 2,4-dichlorophenol, sodium pentachlorophenol as the first target pollutant degradations and the UV lamp as light source to composed the photocatalytic degradation system. The effects the degradation of chlorinated phenol were given according to investigation the amount of Ag doped, initial concentration and pH value of Ag/TiO₂ photocatalyst. The experimental results showed that the amount of silver and the initial concentration greatly affected the three kinds of phenolic compounds. It is very important to select the appropriate amount of Ag. And in the process of the actual treatment of wastewater with phenol, the concentration of wastewater should be paid special attention. Through orthogonal test to determine the optimal conditio ns for the degradation, it was found that Ag/TiO₂ catalyst showed a certain degree of similarity in the degradation process of phenol, 2,4-dichlorophenol, pentachlorophenol photocatalytic oxidation.In fourth part, under the UV irradiation, the degradation kinetics and mechanism of the modified TiO₂ photocatalys with Ag doped were discussed about phenol, 2,4-dichlorophenol and sodium pentachlorophenol. It is found that when the deposition of heavy metals on the surface of TiO₂ is very effective for improving the efficiency of photocatalytic reaction. And the reaction mechanism mainly contains hydroxyl free radical oxidation.