Catalytic Oxidation And Degradation Mechanism Of Simulated Organic Wastewater By Using Chlorine Dioxide As Oxidant

The thesis mainly studied the chlorine dioxide heterogeneous catalytic oxidation method, chlorine dioxide heterogeneous photocatalytic oxidation method and chlorine dioxide homogeneous photocatalytic oxidation method to degrade simulated wastewater containing basic fuchsine, and the corresponding catalysts were prepared for different treatment processes. The degradation mechanism of simulated wastewater containing basic fuchsine of different treatment processes were further investigated by UV-vis spectrophotometric analysis, FTIR analysis, or online FTIR analysis during the wastewater treatment.In the experiment of chlorine dioxide heterogeneous catalytic oxidize simulated wastewater containing basic fuchsine, the normal activated carbon-(MnO2-Fe2O3-NiO) catalyst and ultrasonic activated carbon-(MnO2-Fe2O3-NiO) catalyst were prepared by the normal dipping-calcination method and ultrasonic dipping-calcination method with activated carbon as a carrier. The result show that the ultrasonic activated carbon-(MnO2-Fe2O3-NiO) catalyst calcinated at400℃for3h after ultrasonic dipping1h has higher catalytic activity in treating the simulated wastewater containing basic fuchsine. The CODCr removal efficiency and decolor efficiency of2680mg/L basic fuchsine by catalytic oxidation with ordinary activated carbon-(MnO2-Fe2O3-NiO) catalyst and ultrasonic activated carbon-(MnO2-Fe2O3-NiO) catalyst were91.4%,93.7%and93.8%,95.6%, respectively, at the condition of the optimum pH value was1.2, the dosage of chlorine dioxide was800mg/L, the dosage of catalyst was4g by reacting40min. The CODcr removal efficiency of chlorine dioxide chemical oxidation is44.9%. The ultrasonic activated carbon-(MnO2-Fe2O3-NiO) catalyst did not lose activity until using nine times. In the end, on the basis of the experiment data, the degradation reaction mechanism of basic fuchsine by chlorine dioxide catalytic oxidation was proposed.In the experiment of chlorine dioxide heterogeneous photocatalytic oxidize simulated wastewater containing basic fuchsine, the heterogeneous photocatalyst TiO2/SiO2was prepared by normal dipping-calcination method using silica gel as catalyst support. The optimum treatment conditions were as follows:the volume of wastewater containing150mg/L basic fuchsine was50ml, ClO2concentration was 6.14mg/L, pH value was5.0, the distance between UV lamp and flask was20cm, UV irradiation time was13min, and photocatalyst concentration was lOg/L. The removal efficiency of basic fuchsine could reach80.0%according to Lambert-Beer standard fitting curve, comparing with46.0%of chlorine dioxide chemical oxidation. It indicated that the photocatalytic oxidation is an effective method to treat simulated basic fuchsine wastewater. The intermediates during the degradation process were obtained by using online infrared spectrum analysis. The degradation reaction mechanism of basic fuchsine by chlorine dioxide heterogeneous photocatalytic oxidation was proposed based upon the experiment evidence. Finally, the kinetics of basic fuchsine and chlorine dioxide were further investigated.In the experiment of chlorine dioxide homogeneous photocatalytic oxidize simulated wastewater containing basic fuchsine, certain concentration of ammonium nitrate was used as a homogeneous photocatalyst. The treatment conditions were as follows:the volume of wastewater containing150mg/L basic fuchsine was50ml, ClO2concentration was12.28mg/L, pH value was4.4, the distance between UV lamp and flask was20cm, UV irradiation time was13min and photocatalyst concentration was8g/L. The removal efficiency of basic fuchsine could reach66.4%according to Lambert-Beer standard fitting curve. The degradation reaction mechanism of basic fuchsine by chlorine dioxide homogeneous photocatalytic oxidation was proposed based upon the experiment evidence.The research results show that the methods of chlorine dioxide catalytic oxidation and chlorine dioxide photocatalytic oxidation could both effectively degrade simulated wastewater containing basic fuchsine. The study of degradation mechanism and kinetics would provide innovative technical supports for water treatment technology development.