Degradation Of Dye Wastewater By Catalytic Wet Oxidation Under Room Temperature And Atmospheric Pressure

Wet air oxidation (WAO) is an effective treatment method to destroy hazardous and high concentrated organic pollutants in wastewater. However, WAO process requires high temperature and high pressure, the severe operating conditions can lead to high installation costs, and thereby practical applications of this process are limited. In order to solve this problem, catalytic wet oxidation (CWO) under room temperature and atmospheric pressure was developed in this disssertation, which allowing the possibility to treat polluted wastewater without a too large energy consumption. The preparing of heterogeneous catalysts with high activity and stability is one of key techniques in CWO process under room condition. Accordingly three new kinds of heterogeneous catalysts had been prepared, and the catalytic activity of three prepared catalysts were investigated in CWPO and CWAO process by using three azo dyes (Acid orange 52, Acid orange 7 and Reactive black 5) as model pollutants. The kinetic and degradation mechanism of dyes in CWAO process under room condition were studied, and CWAO process was also evaluated to treat actual dye wastewater combined with biofilm technology.Fe₂O₃/γ-Al₂O₃ catalyst was prepared by the impregnation method. The structure of Fe₂O₃/γ-Al₂O₃ was characterized and the catalytic activity was investigated in CWPO process under room condition. The results show that Fe exists asα-Fe₂O₃ crystal in Fe₂O₃/γ-Al₂O₃ with the loading amount of 1.907% and about 75% degradation efficiency could be achieved within 3h for treating synthetic dye wastewater (the concentration of acid orange 52 was 500 mg/L).Fe₂O₃-CeO₂/γ-Al₂O₃ catalyst was prepared by selecting Ce as doping agent to improve the catalytic activity of Fe₂O₃/γ-Al₂O₃. According to the structure analysis, better dispersion and smaller size of Fe₂O₃ crystals could be obtained by the addition of CeO₂, which made the number of active site increased. Additionally, the content of chemisorbed oxygen also could be increased on the surface of catalyst, which can help to produce·OH instantly. In Fe₂O₃-CeO₂/γ-Al₂O₃ catalyst, the CeO₂ could be acted as structural and electronic promoter. The results of CWPO experiments suggested that azo dyes in simulated...