Study On Preparation Of BaTiO₃ Composites Using Microwave Hydrothermal Method And Their Catalytic Activity Under Visible Light

With the development and progress of the chemical industry, a lot of dyes are needed in the industrial production especially the printing industry, and the amount of dye wastewater which was produced in the industrial production progress is large. Dye wastewater contains many stable organic pollutants which are once released into the water will bring very serious environmental pollution problems. Therefore, the treatment of dye effluent is an environmental problem which needs to be solved urgently. People are also paying more attention to study the waste water treatment technology. Photocatalytic oxidation technology is a very effective method to dispose sewage, so more and more people pay attention to the photocatalytic performance of photocatalytic materials. BaTiO3 photocatalysis technology will be a research trend in the field of water treatment.However, BaTiO3 as the photocatalytic material has two drawbacks:One is that the band gap of BaTiO3 is 3.3 eV similar to TiO2, which greatly limits the use of visible light. The other is that the electronic (e-) and holes (h+) are easily composited, which also affect the photocatalytic efficiency. Thus, it is very necessary to improve its photocatalytic performance through a variety of methods. Wherein, the compounding of BaTiO3 is a more effective method.In the first part of this paper, the catalyst of BaTiO3, Ba0.5Ca0.5TiO3 and CaTiO3 which were used to degrade azo fuchsine were prepared by microwave hydrothermal method. Then the factors includes microwave hydrothermal synthesis time, microwave hydrothermal synthesis pressure, the initial concentration of azo fuchsine, visible light irradiation time, catalyst dosage, irradiation power which affect the degradation efficiency of catalyst were investigated. The results showed that when used Bao.5Cao.5Ti03 and BaTiO3 to degrade 10 mg/L of azo fuchsine solution 24.0 h under visible light respectively, the degradation rate was 93.4% and 89.6%. The adsorption of CaTiO3 was very large as high as 59.62%. This experiment also examined the degradation products by ion chromatography and high performance liquid chromatography. Results proved that azo fuchsine solution were finally oxidized into inorganic molecules and water, carbon dioxide.In the second part three catalysts of Ba0.5Mg0.5TiO3, Ba0.5Ca0.5TiO3 and Ba0.5Sr0.5TiO3 were also prepared by microwave hydrothermal method. Rhodamine B as the target pollutants were used to study microwave hydrothermal synthesis pressure, microwave hydrothermal synthesis time, visible light irradiation time, visible light irradiation power how to affect the degradation efficiency of catalyst. The results showed that when use 2.0 g/L catalyst under visible light to degrade 10 mg/L rhodamine B solution, after 8.0 h the degradation efficiency of Ba0.5Sr0.5TiO3 was best, its degradation rate reached 100%, and the degradation rate of Bao.5Cao.5Ti03 and Bao.5Mgo.5Ti03 were 88.56%,77.95% respectively. We also use ion chromatography and high performance liquid chromatography to detect the solution which have been degraded. The results showed that all of the three catalysts can degrade rhodamine B into small inorganic molecules matters and water, carbon dioxide.