| Anthraquinone dye is the second most used dye in current, this kind of dye has characters such as complex structure, high color biodegradable, toxic, water-soluble strong and difficult to deal with. Traditional method to degradation this kind of pollutant is not satisfied. Some researches show that synergy between oxidants can produce a higher concentration of hydroxyl radicals. The radicals can improve oxidation capability of the system. We used transition metal ions as a catalyst add to the oxidizer compound system, this system can enhance the capability of decompose oxidant to reactive oxygen or radical, thus could improve efficiency of disposed organic pollutants by use oxidant.This paper used typical anthraquinone dye Reactive Brilliant Blue KN-R as experimental target. We investigated the process of transition metal ion catalyzed H2O2/O3 synergistic oxidative degradation KN-R, establishment a system of Mn2+/H2O2/O3 oxidating degradation. Analyze the main factors:catalyst, Mn2+ concentration, H2O2 concentration, initial pH, temperature, limit degradation of concentration and water common anions, influence the degradation result, then we studied the degradation mechanism. The results show that:(1)Establish method of Mn2+/H2O2/O3 system degradation reactive brilliant blue KN-RWe added five catalysts:MnCl2, CoCl2, CrCl3, NiCl2 and ZnSO4 into H2O2/O3 system and studied their influence on KN-R decolorization rate, according to the result we choose MnCl2 as experimental catalyst. Then studied the degradation effect of KN-R system in H2O2, O3, H2O2/O3, Mn2+/H2O2, Mn2+/O3 and Mn2+/H2O2/O3. The result shows that in H2O2/O3 system, H2O2 and O3 synergistic effect to produce OH was not obvious. After introduce transit metal Mn2+ into H2O2/O3 system, Mn2+ could react with O3 then form hydration state of Mn4+, the-OH concentration of MnO2 hydrated solid surface higher than other places of the solution, O3 react with-OH, generate hydroxyl radicals OH on MnO2 surface, the hydroxyl radical oxidation of water react with brilliant blue KN-R; Mn2+ could catalysis H2O2 in some certain extent and increase system oxidative ability, Mn2+/H2O2/O3 system has obvious synergy.(2)Main factors influenced Mn2+/H2O2/O3 system degradation efficiencyKN-R initial concentration was 100mg/L, room temperature, ozone ventilation 400ml/min, the initial pH was 4,30% H2O2 dosage was 32.65mmol/L, MnCl2 dosage was 0.1mol/L, reaction time was 5min under the conditions of Mn2+/H2O2/O3 system, KN-R decolorization rate was 65.26%. Anion and·OH reaction rate shows that HCO3- may affect the formation of·OH, and thus have an impact on the oxidation process. However, the inhibition effect of anion·OH was relative, with different experimental conditions changed, such as NO3-, SO42-, Cl-, has very little influence on KN-R decolorization rate in Mn2+/ H2O2/O3 system.(3)Analysis mechanism of Mn2+/H2O2/O3 system synergetic degradation KN-R dyeAdded different concentration of tert-butyl alcohol into the process of degradation KN-R, analysis the function of OH, it was proved that the main factor influence oxidation in 2+/H2O2/O3 system was OH. After that, we compared three different systems:H2O2/O3, Mn2+/H2O2. and Mn2+/H2O2/O3. analysis change of H2O2 content during KN-R degradation in this three systems. Results shows that after 60min the concentration of H2O2 in Mn2+/H2O2/O3 system was only 11.3mmol/L, synergy effect was very significant. Combined COD and TOC of Mn2+/H2O2/O3 system degradation, analysis UV-vis spectra and ion chromatographic in degradation processes, we speculated that mechanism of KN-R degradation path was:great conjugate color system form by anthraquinone structure of KN-R molecules and its attachment auxochrome group was first destroy by OH which produced from Mn2+/H2O2/O3 system, and gain small molecular acid in template material, with the oxidation process gone on, those template material will complete mineralized to small molecular and ion such as N2, CO2, H2O, SO42-, NO3-, etc. |
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