Preparation, Characterization Of Ag-Agbr/Carrier Photocatalyst And Its Application In Treatment Of Azodyes Wastewater

Azodyes are ubiquitous commercial organic compounds that are detrimental to the environment. Numerous effluents are discharged into publicly water treatment plants and these effluents are mostly nonbiodegradable and difficult to eliminate by physico-chemical treatment methods. Photocatalytic Oxidation Technology can transform these organic dye pollutants effectively to environmentally harmless substances through redox reaction. Therefore, the photocatalytic degradation of organic contaminants has drawn the most attention.Silver bromide (AgBr) is an important visible light photosensitive material which can absorb a photon in the visible and shorter wavelengths to liberate a photoelectron and a photohole. It has been found that AgBr could maintain its stability and enhance the photocatalytic activity if it is dispersed on certain support materials.In this paper, we have reported a facile way of preparing Ag-AgBr/Carrier by deposition-precipitation method with carrier. Three azodyes (Acid Red B (ARB), Acid Chrome Blue K, Lemon Yellow85) were selected as model chemicals to evaluate the activity and properties of the catalyst. There are three aspects works carrying out as following:1. Preparation, Characterization of Ag-AgBr/TiO2Photocatalyst and its Application in Treatment of Azodyes WastewaterBoth of Ag-AgBr/TiO2and Ag/TiO2photocatalysts were prepared and used in the treatment of azodyes wastewater. The result shows that Ag-AgBr/TiO2gains much better activities than Ag/TiO2, which indicates that AgBr is the main photoactive species for the decomposing of azodyes under visible light. Three different kinds of azodyes were used to evaluate the activity and the degradation efficiency of the catalyst for ARB was the highest. Therefore, we can conclude that the structure of azodyes has an effect on the degradation rate.2. Preparation, Characterization of a Series of Ag-AgBr/TiO2Photocatalyst and its Application in Treatment of Azodyes Wastewater A series of Ag-AgBr/TiO2samples were prepared with the mass ratio of AgNO3and TiO2in the samples was158.32%,101.92%,41.98%,20.99%, and10.49%. The result shows that as the mass ratio of AgNO3and TiO2is increased from10.49%to101.92%, the percentage of degradation increased. After this point, further increase of the mass ratio of AgNO3and TiO2decreases the percentage of degradation. The best photocatalyst-101.92%Ag-AgBr/TiO2can reach79%decolorization efficiency in10minutes which is currently the best results reported in the literature. The main reason is that photocatalyst can form a stable and uniform structure at this ratio. Excessive AgBr particles could shorten the mean distance between the trap centers of photoelectron and photohole which can lead to higher recombination of electron/hole pairs.3. Preparation, Characterization of Ag-AgBr/Carrier Photocatalyst and its Application in Treatment of Azodyes WastewaterThe nanopowders of the Ag-AgBr/Carrier photocatalysts were prepared using the deposition-precipitation method. γ-Al2O3, TiO2(P25) or Ti-MWW was used as the carriers, cetyltrimethyl ammonium bromide (CTAB) was used as the bromine source in the preparation of photocatalysts. The photocatalytic activity of Ag-AgBr/Carrier was investigated for the degradation of azodyes, especially Acid Red B in aqueous solution using visible light. The result shows that Ag-AgBr/Carrier gain much better activities than carriers which indicates that Ag-AgBr is the main photoactive species for the destruction of azodyes under visible light. Three different kinds of azodyes were used to evaluate the activity and the degradation and adsorption efficiency were different. In general, Ag-AgBr/TiO2is the best photocatalyst for the degradation of azodyes. Because as a n-type semiconductor, TiO2can absorb a photon and liberate a photoelectron and a photohole. The recombination between electron/hole pairs is lower with AgBr added in.