Study On Modification Of Manganese Oxide Preparation And Catalytic Ozonation Performance

Catalytic ozonation is a kind of new technology which was combined of the ozone oxidation and the adsorption of the catalyst.It produces a lot of free radical that has a high activity. These free radical can be used to treat the organic compounds which was difficult to degrade.Catalysts were prepared by incipient wetness impregnation method, hydrothermal method and co-precipitation method. Different approaches such as XRD, SEM, and BET were used to characterize the catalysts. Accordingly, the phase composition, morphology characteristic and specific surface area were obtained. Methylene blue was selected as the model pollutantThe reaction parameters, like the temperature, pH, etc., were studied in detail. The adsorption mechanism and the reaction kinetics was also researched in this paper.The adsorption capacity of the Volcanic rocks、Mn/volcanic rocks、α-MnO2、 δ-MnO2 and γ-MnO2 was evaluated. The adsorption capacity was 16.71mg/g、 12.42mg/g、40.52mg/g、50.87mg/g and 58.47mg/g,respectively. The adsorption process attributes to pseudo second order kinetics model, and the adsorption capacity obtained fitting with pseudo second order kinetics model and the actual measured qe (measured) were very close. The degradation efficiency of catalytic ozonation system were better than the ozonation alone. The catalytic activity of 8-MnO2 was the highest. At the same time, the catalytic ozonation reaction followed pseudo-first-order kinetics. The catalytic activity of the Fe-Mn metal oxides prepared by the calcination of hydrotalcite precursor was higher than that of catalysts prepared by co-precipitation method. The catalytic activity of Fe-Mn composite metal oxide catalyst can be significantly improved by adding 20% glucose. The best dosage of volcanic rocks and Mn/volcanic catalyst was 0.3g, however, the best dosage of 8-MnO2 and Fe-Mn composite metal oxides were 0.5g.The best temperature of experiment was 30℃.Changing the pH of solution, it was found that the degradation efficiency of catalytic ozonation was the best in the alkaline condition. The degradation efficiency was enhanced obviously by the addition of H2O2, however, it was decreased by adding of tert-butyl alcohol. Therefore, it’s infered the catalytic ozonation system followed a hydroxy radical mechanism.The removal of TOC was improved obviously because of the addition of different kinds of catalysts.