The Application And The Study Of Ag/ZnO Nano-composites Synthesized Via Cooridination Homogeneous Precipitation Method

The control and management of environment pollution is one of the most important targets of human being in 21 century. Semiconductor photocatalytic oxidation technology is one kind of advanced oxidation technology, which has many virtues, for example, it can completely oxidize almost all the organics harmful pollutants into CO2 and H2O in the room temperature and pressure, which has no second pollution, so it attracts much attention from scientists in this field. In particular, ZnO has attracted much attention with respect to the degradation of various pollutants due to its being relatively cheap, stability and high photocatalysis. Up to now, many studies have demonstrated that the presence of transition metals (such as platinum, palladium and silver) can improve the charge-transfer and consequently the performance of the photochemical degradation process. In this paper, the coordination homogeneous co-precipitation method,which is different from other methods, is applied to synthesize Ag/ZnO nano-composites. The configuration,growth dynamics and properties of the product has been researched. The main contents and results were as follows:(1) The mechanism and feasibility of preparation of Ag/ZnO nano-composites by the coordination homogeneous co-precipitation method were researched theoretically. The advantage of this method was simple, mild reaction conditions, low cost, easy to realize the scale production and the particle size of the product was small and controllable.(2) In preparation, low-cost ammonia was chosen as the coordination agent, ammonium acid carbonate as a precipitator, zinc oxide and silver nitrate as metal source. The mixture precursor of Zn5(OH)6(CO3)2 and Ag2CO3 were prepared firstly. It was fibrillar nanocrystallin with the diameter and length about 10-30nm and 100-200nm respectively. Differential thermal analysis/thermogravimetry (TG-DTA), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM) were used to characterize the microstructure and morphology of it. The factors affecting the preparation of precursor such as temperature, time and concentration were also studied.(3) The influence on the precursor of the calcining temperature and the growth dynamics of the product were studied in the paper. The results showed that the dynamic growth index was 1.32, indicating that the rate of the grain growth was quick at 300-600 oC. The product was characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM). (4) The photodegradation performance of the methyl orange and industry waste water were studied. And we also compared it with the products prepared by photoreduction method. The results showed that the product prepared by coordination homogeneous co-precipitation method exhibited the excellent performance not only in the photoreduction of methyl orange but also in industry waste water.