Preparation Of Ag/TiO₂Coated Composite And Investigation On Its Photocatalc Deytigradation Of Organic Dyes By Assisted Magnetic Field

As the developing of human society, two major crisis environmental pollutionand energy shortage occurred. In order to solve them, people have found a variety ofmethods. As a photocatalyst TiO₂, because of its low price, non-toxic, the chemicalstability, it not only can degrade pollutants, but also can utilize solar energy to resolvethe problem. However, pure TiO₂only can be excited by UV light, so the hole （h+）and electronic （e-） produced by the light excitation could composite easily, it affectsthe wide application. In order to solve these two problems, Researchers study themodification methods, and have obtained some achievements, but there also need tofurther perfect, to make it not only the outstanding performance, but also morepractical application value.Ag is a kind of metal with fine conduction, stable properties. Under normaltemperature, it cannot react with O2in water and air. Scientific research proves thatthe activity of photocatalyst was improved when Ag composites with TiO₂. Theprinciple of this method is to use the characteristic of precious metals has strongability to hog the electrons transfer to Ag, which makes electron hole to stay in TiO₂and achieves the aim of restraining the recombination of electron and electron hole.Because of the quantity of Ag on the catalyst is limited，when the absorption gets herultimate the electrons will be sent out and composite with hole，which will affect theactivity of catalyst.How to further improve the photocatalytic activity of Ag/TiO₂composite material is the problem which we should pay attention to. Therefore, weput the magnetic field into the photocatalysis experiments, this new method cansuppress the composite of photogenerated electrons and holes preferably.This present study designs some novel Ag/TiO₂composites photocatalysts withsol-gel and chemical decomposition method. All sorts of composite materials werecharacterized by X-ray diffraction spectroscopy （XRD）, scanning electronmicroscope （SEM）, UV-vis diffuse reflectance spectroscopy, etc. The compositematerials crystal, grain size and surface topography were studied. The influence ofexperimental conditions and the structure of photocatalysts were studied, and the best performance condition was selected.Azo dye is one of the common industrial pollutant. In this study, Acid Red B wasselected as model pollutant to characterize the photocatalytic activity of Ag/TiO₂composite under UV and three basic color light irradiation. In this study, the contentof Ag, processing temperature and processing time were studied and the irradiationtime, the initial concentration of dye, rotate speed and magnetic field intensity werealso studied. At last, other dyes were used to degradation to research the universalutility of photocatalyst. It proves that the degradation of dye with Ag/TiO₂compositeusing magnetic field. The mechanism of photocatalytic degradation was discussed. Inother word, potential difference happened under conductor cut field lines, and theelectron was consumed under photocatalytic activity on anode. On the other hand, theelectron made on node was consumed during this action. In according to this theory,the photocatalytic activity was enhanced.