| Azo dyes wastewater belongs to the highly concentrated organic wasterwater, which is difficult to be biodegradation. Not only because its'high chromaticity, strong noxious, but also easy decompose to carcinogenic compounds. Therefore the effect is not satisfactory for the traditional approach, azo dyes has become to the problem of industrial wastewater treatment. Single physical chemical methods, although could be degrade effectively, but the oxidized efficiency needs to be further improved. While, recent years'research indicated: the combination between the advanced oxidation processes, which produced to high concentration of hydroxyl radicals, thereby improved the oxidative capacity of system, became one of kinds of the preferred method in dealing with such dyes.In this paper, the typical azo dye of reactive brilliant red X-3B was taked as the object, and to study their coordination in the catalytic oxidation of Mn2+ and photocatalytic oxidative degradation process, established the oxidative system of UV/Mn2+-H2O2. And also the conditions and mechanism of decomposing process of X-3B was analysised in UV/Mn2+-H2O2 system. The influence about decolorization effect of solution was researched by primary factors which were the concentration of Mn2+and H2O2, pH value, limit degradation and inorganic anions. The results showed as follows:(1) The establish of UV/Mn2+-H2O2 on the degradation of active X-3BMnSO4 was selected as the catalyst for the experiment, based on the research of five catalysts ( MnSO4,MnO2,CeO2,CuSO4,ZnSO4 ) degradation of X-3B on catalysis hydrogen peroxide solution. The rate constants of decolorization was 0.003, 0.0368 and 0.0951min-1 in Mn2+/H2O2, UV/H2O2 and UV/Mn2+-H2O2 system, respectively. The degradation rate of X-3B in the UV/Mn2+-H2O2 process was 2.6 times higher than the combination of two seperate function, catalytic synergy remarkable.(2) Analyze the major effect factor to the degradation of X-3B in UV/Mn2+-H2O2 system0.59mmol/L of the Mn2+,10 mmol/L of the H2O2,pH=6 and a high level of DO lead to the improvement in X-3B degradation. And when the concentration of dye was 500mg/L, the degradation of dye achieved 295 mg/L, utmost. Through the decolorization rate and the determination of residual H2O2 in the reaction process, confirm the inhibit pathway of anion to the X-3B's degradation was: NO3- was found to inhibit the effect of degradation by impeding the ultraviolet through the solution to obstruct the decomposition of H2O2. While, the·OH from the solution was captured directly in the inhibit pathway of Cl- and SO42-.(3) Mechanism of Degradation of Dyes in the UV/Mn2+-H2O2 systemAdded different concentrations of methanol, which was the quenching medicinal preparation of·OH, the influence of the degradation verified the main role of UV/Mn2+-H2O2 system was·OH oxidation. Compared with the degeneration of reactive brilliant red X-3B under the three kinds of systems: UV/H2O2,H2O2/Mn2+,UV/Mn2+-H2O2. The result indicated that the UV/Mn2+-H2O2 system had the synergism of Mn2+/H2O2 and UV/H2O2, the residual amount of H2O2 was 1.52mmol/L, the elimination rate of TN and TOC were 20.65% and 56.45%. Combined with the analysis of UV-vis spectrum and the ion chromatographic, initially speculated that the degradation pathway of X-3B followed the mechanism of hydroxyl radicals. After reaction, the concentration of Cl-,NO3- and SO42- in solution was 0.4,0.039 and 0.877 mmol/L, respectively.(4) The research of X-3B degradation in the group technology of UV/Mn2+-H2O2 and adsorption.It was promoted the degradation of reactive brilliant red X-3B in the group technology of UV/Mn2+-H2O2 and carbon. The removal rate of TOC and TN was effectively improved, achieved 77.75% and 62.87% respectively. Simultaneously, the iron concentration of the solution, specially the density of SO42- and NO3-, increased to 1.072mmol/L and 0.2715mmol/L separately.
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