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Study On Surface Morphology Control And Catalytic Oxidation Performance Of Manganese Dioxide

Posted on:2017-10-12Degree:MasterType:Thesis
Country:ChinaCandidate:C Y WangFull Text:PDF
GTID:2311330482996080Subject:Environmental Science and Engineering
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This paper was mainly researched that ??????? and ? crystal nanometer manganese dioxide were prepared by the hydrothermal method,aqueous coprecipitation and ozone oxidation method directly.The crystal structure and morphology of nanometer manganese dioxide were controlled by changing the reaction temperature,the ratio of reducing agents to oxidant,reductant species,oxidant species,reaction pH value,reaction time and adding different kinds of small molecule alcohol.All the prepared materials were characterized by XRD,SEM,TEM and BET to obtain the information of crystal structure,morphology and their transiton mechanism of different crystals.In this work,methylene blue is selected as the model pollutant.The adsorption effects and the adsorption dynamics by different crystal type nanometer manganese dioxide were studied.In addition methylene blue wastewater was oxidized by hydrogen peroxide using nanometer manganese dioxide as catalysts.Catalytic hydrogen peroxide oxidation were analyzed by investigating different crystal types,quality of catalyst,pH,temperature and other conditions.The experimental results are as follows:On the hydrothermal method and the aqueous coprecipitation processing conditions,the crystal types and the morphology of manganese oxide were influenced by changing the amount of reductant,temperature,reductant species,oxidant species,reaction time and pH.And the general law of crystal type transition obtained was ?-?-?-?-MnO2.The adsorption capactiy of each crystal type manganese dioxide was evaluated and the adsorption effect was ?????????-MnO2.The adsorption capacity was 78.28mg/g?73.23mg/g?56.1mg/g?45.375mg/g and 14.38mg/g,respectively.The adsorption kinetics Conformed to the secondary adsorption rate equation.The degradation efficiency of catalytic hydrogen peroxide system were better than the hydrogen peroxide,and the catalytic efficiency was ?????????-MnO2.It was found that ?-MnO2 ??-MnO2 were best catalysts and the degradation efficiency was 99.3% and 95.6%,respectively.The crystal types of nano manganese dioxide were generally constant and the morphology were alterant after catalyzing.It showed that the best dosage of catalyst was 0.2g and the best dosage of H2O2 was 15 m L.The degradation efficient was enhanced obviously by addition of O3.
Keywords/Search Tags:Crystal, Manganese dioxide, Methylene blue, Hydrogen peroxide, Hydrothermal method, Aqueous coprecipitation method
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