Study On The Visible Light Catalytic Activity Of Ag₂C₂O₄ And P25-Ag₂C₂O₄ For The Oxidation Of Organic Pollutants

In recent years, with the rapid development of the science and technology of China, the increasing environmental pollution problems gradually become more and more serious. So far, the air and water pollution has become the global environmental pollution phenomenon that urgently needs to be addressed. Because of wider range of sources, lower cost, higher chemical stability advantages etc, titanium dioxide was widely applied in the study of the control of the environment pollution. But the forbidden band width of TiO2 is 3.2 eV, which makes the titanium dioxide can only be excited by sun’s ultraviolet light, largely limiting its application in actual production and life. Therefore, it is necessary for many researchers to develop a new type catalyst with highly efficient and stable visible light activity.In this paper, the silver oxalate and the composite photocatalyst P25-Ag₂C₂O₄ are synthesized. Furthermore, Ultraviolet-visible diffuse reflection spectroscopy（UV-Vis）, X-ray powder diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and X-ray photoelectron spectroscopy（XPS） were conducted to characterize the property of Ag₂C₂O₄ and P25-Ag₂C₂O₄. The photocatalytic activity of samples was also evaluated by the degradation of the simulated waste gas under visible light irradiation and different reaction conditions. In conclusion, the main research contents of this topic are as follows:（1） Silver oxalate with monoclinic system was synthesized. The characterization of silver oxalate was analyzed, and the photocatalytic activity of photocatalyst was also studied in five cycles experiment. Then, we can inferred that the possible mechanism of pollution degradation over silver oxalate under visible light irradiation.（2） The series of P25-Ag₂C₂O₄ composite photocatalysts with different proportions have been prepared by a simple chemical precipitation method. By comparing the photocatalytic activity of P25-Ag₂C₂O₄ series with different proportions（10:0.2, 10:0.8, 10:1.0, 10:1.5, 10:2.0, 10:2.5, 10:2.7 and 10:3.0）, we can find out the best mass ratio of the composite material photocatalyst P25-Ag₂C₂O₄.（3） By comparing the scanning electron microscopy（SEM） graphs and the transmission electron microscopy（TEM） images of silver oxalate and P25-Ag₂C₂O₄ composite photocatalyst, it can be observed whether the morphology of silver oxalate will be changed after combining with titaniumdioxide.（4） By examing the influence of the circulating water temperature on the activity of P25-Ag₂C₂O₄ composite photocatalyst to study whether the temperature has a promoting effect on the degradation efficiency of photocatalyst P25-Ag₂C₂O₄. Namely, with the increase of the circulating water temperature, whether the degradation rate for simulated waste gas increased either. In addition, the kinetic constant k and the curve correlation coefficient R2 of the composite photocatalyst P25-Ag₂C₂O₄ with the best mass ratio are studied too, and by analyzing the degradation of simulated waste gas, we can know that whether the degradation reactions over the composite photocatalyst P25-Ag₂C₂O₄ belong to the first-order dynamics reaction.（5） The photocatalytic activity of the composite photocatalyst P25-Ag₂C₂O₄（different mass ratio） were also evaluated by the removal of acetaldehyde as a representative of VOCs（volatile organic compounds） under visible light irradiation. It was found that P25-Ag₂C₂O₄ composite material has good performance on the degradation of acetaldehyde. Therefore, the actual application value of P25-Ag₂C₂O₄ composite photocatalyst with different mass ratio in the degradation of VOCs（volatile organic compounds） has been confirmed.