Investigation On Preparation Of Ferroferric Oxide Supported On Carbon Nanotubes And Microwave Catalytic Degradation Of Organic Pollutants In Aqueous Solution

In this study, three methods including microwave hydrothermal method, hydrothermal method and coprecipitation method for preparing ferroferric oxide supported on carbon nanotubes （Fe₃O₄/CNTs） were studied and applied in the treatment of organic pollutants in aqueous solution. These organic pollutants in aqueous solution are methyl parathion （MP）, diuron （Diuron）, azo fuchsine （Azo-fuchsine）, etc. The 20-40 nm and 40-60 nm CNTs were used in this experiment.In the first chapter, microwave hydrothermal method was introduced to prepare Fe₃O₄ surpported CNTs （Fe₃O₄/CNTs） catalyst. The particle size of the carbon nanotubes was 40-60 nm, which combined with microwave to degrade the organic pollutants in wastewater. The microwave catalytic activity of both ferriferrous oxide supported on carbon nanotubes （Fe₃O₄/CNTs） and carbon nanotubes （CNTs） were compared. The results show that the organic pollutants in aqueous solution such as methyl orange （MO）, bisphenol A （BPA）, methyl parathion （MP）, Rhodamine B （RhB）, and azo fuchsine （Azo-fuchsine） can be degraded quickly in the Fe₃O₄/CNTs /MW system. For 1.0 MPa microwave hydrothermal synthesis pressure and 30 min microwave hydrothermal synthesis time, and 0.04 mol/L Fe3+ concentration, Fe₃O₄/CNTs showed the highest microwave catalytic activity. Changing the microwave hydrothermal synthesis pressure to 1.5 MPa, using the same microwave hydrothermal synthesis time, the Fe3+concentration of Fe₃O₄/CNTs,38 μmol/L （i.e. 10 mg/L） methyl parathion （MP）,1.2 g/L catalyst dosage,450 W microwave power, 2450 MHz, pH= 6.2, and 1.5 min microwave irradiation time, the methyl parathion could be degraded completely. In additon, methyl orange （MO）, bisphenol A （BPA）, methyl parathion （MP）, Rhodamine B （RhB） and azo fuchsine （Azo-fuchsine） were degraded in the Fe₃O₄/CNTs/MW system, and the calculated rate constants （k） are 0.925,0.845,0.753,0.993 and 0.943 min-1 for MO, BPA, MP, RhB and Azo-fuchsine, using 40-60 nm Fe₃O₄/CNTs/MW system, respectively. Under the same synthesis and degradation conditions, the microwave catalytic activity of the Fe₃O₄/CNTs is higher than that of the pure CNTs.In the second chapter, microwave hydrothermal method, hydrothermal method and coprecipitation method were applied to prepare ferroferric oxide supported on carbon nanotubes （Fe₃O₄/CNTs）. In this chapter, the 20-40 nm carbon nanotubes were selected in the research. The microwave catalytic activities of three methods to prepare Fe₃O₄/CNTs were compared. The organic pollutants in aqueous solution was studied, such as bisphenol A （BPA）, azo fuchsine（Azo-fuchsine）, diuron （Diuron）, methyl parathion （MP）, methyl orange （MO） and Rhodamine B （RhB）. Microwave hydrothermal method, hydrothermal method and co-precipitation method were used to prepare the Fe₃O₄/CNTs catalysts, and under the microwave irradiation, the above several organic pollutants can be degraded quickly and effectively. Three methods were introduced to prepare the Fe₃O₄/CNTs catalysts.0.02 mol/L Fe3+ concentration, 0.4 g/L catalysts,25 mL,10 mg/L diuron （Diuron）,450 W, and 1.0 min microwave irradiation time were used, and the degradation rate are 43.91%,47.10% and 60.37 %, respectively. Therefore, the order of activity of the three Fe₃O₄/CNTs is as follows: the Fe₃O₄/CNTs of co-precipitation method> the Fe₃O₄/CNTs of hydrothermal method> the Fe₃O₄/CNTs of microwave hydrothermal method.In summary, the Fe₃O₄/CNTs and CNTs have the microwave catalytic activity, and the organic pollutants can be degraded quickly and effectively. Under the microwave irradiation, the degradation activity of Fe₃O₄/CNTs is higher than that of CNTs. Fe₃O₄/CNTs prepared by co-precipitated exhibited the highest catalytic activity of the three methods under MW irradiation.