Preparation, Characterization Of Ag/BiVO₄Photocatalyst And Study The Photodegradation Mechanism Of Tetracycline Antibiotic With Ag/BiVO₄Catalytic Action

This study using hydrothermal synthesis method to synthesize a variety of different load amount of Ag Ag/BiVO4photocatalyst, using SEM, XRD, UV-vis characterized the performance of Ag/BiVO4samples. Selection for antibiotic chlortetracycline hydrochloride on behalf of content, this paper studied the influence factors of catalytic degradation of CTC with Ag/BiV04under the ultraviolet and visible light irradiation. Considering the practical wastewater is contained in the main ions and main substance of the impact of the CTC degradation, such as the pH, Ca2+, Mg2+and NO3-factors affecting the relationship with the CTC degradation are analyzed. At the same time the preliminary study on the mechanism of catalytic degradation of CTC with the presence of Ag/BiVO4catalyst has been carried on and using TOC analysis to analyse the process of catalytic degradation product, to determine whether the CTC was completely catalytic degradation. In addition to using the sun light energy Ag/BiVO4catalytic degradation of CTC experiment under the sunlight irradiation were carried on, verify the sun Ag/BiVO4real feasibility of catalytic degradation of CTC.Ag/BiVO4catalyst were synthesised by hydrothermal synthesis method and showed good visible light catalytic activity, the SEM results show that the Ag/BiVO4catalyst particle size were micron order of magnitude, the smaller the load after Ag to BiVO4appearance irregular structure, size bigger; By XRD analysis results have to load after Ag not phase change BiVO4monoclinic crystal structure; UV-vis spectrum obtained BiVO4main absorption wavelength were445run, load Ag Ag/BiVO4after the main absorption wavelength were540nm, Ag/BiVO4has better visible absorption performance than BiVO4.The influence factors of catalytic degradation of CTC with Ag/BiVO4were studied under UV and visible light irradiation. When the UV light can make the CTC in the oxidation and degradation of its occurrence rate is slow, absorption wavelength of BiVO4is more similar with the UV wavelength than Ag/BiVO4catalysts and show better catalytic degradation activity of CTC. Under visible light irradiation, the nature of the CTC degradation stability are less, Ag/BiVO4catalyst showed good catalytic degradation activity of CTC, load Ag structure to BiVO4appearance is irregular, after experiment Ag load of2%of the Ag/BiVO4catalyst has the best catalytic degradation of CTC performance. Photocatalytic belongs to heterogeneous reaction, the catalyst is fixed with pseudo-first-order reaction kinetics equation, the catalytic degradation of CTC rate is limited by the CTC concentration, too high or too low concentration of CTC will reduce the degradation rate. A suitable amount of catalyst can effectively promote the CTC photolysis, excessive catalyst can weaken in the optical system of energy utilization efficiency, hinder the CTC degradation. pH influences the CTC existence forms in water, weak acid and neutral environment conducive to the Ag/BiVO4catalytic degradation of CTC. Alkaline environment could suppress Ag/BiVO4catalytic activity, reduce the CTC photodegradation rate. Ca2+and Mg2+in water chelated with CTC, generate against with Ag/BiVO4catalyst adsorption-chelate, reduces Ag/BiVO4catalytic CTC degradation rate. NO3-for photosensitive sex material, the visible light irradiation can produce active oxide material such as· OH promoted Ag/BiVO4catalytic degradation for the CTC.The mechanism preliminary study of catalytic degradation of CTC with Ag/BiVO4has carried on and the process of catalytic degradation products of was analysed by TOC analysis. Ag/BiV04under visible light irradiation in the process of catalytic degradation of CTC, OH, the catalytic oxidation of dominant, followed by O2-·oxidation; h+hole was not directly involved in the oxidation process, but participation generated indirect catalytic oxidation·OH free radical reaction. Ag/BiV04catalyzed CTC fully biodegradable, generate CO2and H2O, catalytic process for multiple steps, there is stability than the middle of the CTC substance is formed.To take advantage of the sun light energy catalytic degradation experiment of CTC with Ag/BiVO4under the sunlight irradiation, the result of the experiment on the surface of the sun Ag/BiVO4catalyst can be catalytic photodissociation CTC; the sun light can make the CTC degradation by oneself, but speed is very slow.