The Study On Synthesis Of Silver Bromide Nanoparticles And Its Photocatalytic Activity

In recent years, the treatment of industrial dye wastewater has become a major problem. As the dye wastewater it has toxicity, high color and poor renewable characteristics. The degradation of the traditional methods can not effectively remove the organic pigments. So looking for a way to deal effectively with new technology of dye wastewater has been the focus of our concern.The Photocatalytic method has many virtues that are simple technics equipment, without second pollution and oxidation ability. As a new method which is getting people's attention. Silver halide is a very important class of semiconductor materials. It is widely used in magnetic, optical, electrical and other fields. In addition to its optical information storage materials and it can also be used as photocatalysts. Nano-silver halide particles have high surface activity, high surface energy and quantum confinement effect features. It has a higher degradation rate than the large size of the silver halide particles. However, it is difficult to obtain dispersed, nanosize particles of silver halides by traditional methods. In order to get nanoparticles, there are many new methods to preparation nanoparticles. We mainly used Microemulsion and liquid precipitation method to prepare silver bromide nanoparticles. Through the preparation of silver bromide nanoparticles which make a study about its photocatalytic properties.Microemulsion is an isotropic, transparent and thermodynamically stable system. Since the 1980s, W/O microemulsion method has to be used to prepare various nanoparticles. This paper uses silver nitrate (sodium bromide) solution/pentanol/ TritonX-100/cyclohexane and silver nitrate (sodium bromide) solution/heptane/ AOT was prepared by the two systems of silver bromide nanoparticles. It can be seen The microemulsion system which using AOT as surfactant prepared nano-particle is uneven. Most of the particles between 80-150nm in diameter, a amount of particle size more than 200nm. The use of TritonX-100 as surfactant, prepared from the microemulsion system of uniform nano-particles, particle size is 71nm. The domestic AOT is mainly used for industrial production which may contain a small amount of impurities. AOT is easy to absorb moisture and thus affect the stability of their micro-emulsion. Because of these factors make the resulting uneven distribution of nano-particle size.At the same time, we adopted the liquid phase precipitation method to prepare nano-particles of silver bromide. In this method, I used CTAB as surfactant. CTAB micelles in the water, thereby limiting the reaction can be limited only within the small region. This can make the size of nanoparticles has been limited and prevents further aggregation of nanoparticles. By using XRD, SEM, DLS analysis methods that can determine the preparation of silver bromide nano-particles have high purity and uniform particle size distribution. By its IR and UV-visible spectral analysises, we can see CTAB have a good modification for the silver bromide nanoparticles. And this nanoparticles has absorption in the visible region. Through the analysis of their TGA we can know, when the solution temperature is less than 210℃can be used as a catalyst. It also discusses the reaction time, reaction temperature, reaction concentration, concentration of different surfactants and different ratio of reactants and other conditions on the impact of the product. The optimum conditions:at room temperature, the reaction spent 4h, the concentration of reactants is 0.5mol/L, uniform particle size distribution can be obtained about the size of nanoparticles 45nm. In the last part, we make a research about the photocatalytic activity of Silver bromide nanoparticles. Through the illumination time, the type of light source, the concentration of methyl orange, amount of catalyst, particle size and the pH value of solution analysises, we can see silver bromide nanoparticles catalysts are stable and have high degradation efficiency. In natural light conditions, it can undertake degradation reaction. Under acidic conditions, it has higher photocatalytic efficiency. Compared with TiO2 and ZnO nanoparticles, the Silver bromide nanoparticles is degradation rates in 90% above.