| Printing and dyeing wastewater was very complex and characterized by heavy colority, high toxicity, alkaline and. It caused great harm to the environment and human health, so innocuous treatment of dyeing wastewater has become an important problem in printing and dyeing industry and the environment protection. Currently, bleaching methods mainly include biology method, chemical methods, physical-chemical and other ways generated by high-end technologies, the most common method was the mutual cooperation in the treatment of dyeing wastewater. CWPO (Catalytic Wet Peroxide Oxidation) has bocome a promising technology because of its high efficiency, response speed, small secondary pollution, and moderate treatment conditions, etc. Therefore, researchers gradually pay great attention on it.The residual dye molecules of printing and dyeing wastewater are the main reason to cause the heavy colority and high COD, so it has a very practical significance to remove the dye molecules. In this paper, ten kinds of azo dyes were prepared to simulate printing and dyeing wastewater. And catalysts were prepared by loading ten active metals with zeolite used as carrier. The dye removal rates of diverse catalysts were studyed in CWPO, the metal catalytic activity were also evaluated. Then, three metals (Cu, La and Mo) were selected as the active catalysts, mixed soaking liquid were prepared, a novel kind of metal loaded material, zeolite catalyst (Z/CLM), were prepared. Besides, degradation of three kinds of dyes(direct purple D-BL, direct grey BN, acid black 10B) were also researched. Lots of factors were characteristed, such as the ratio of the active metal, roasting conditions, zeolite particle size, dipping amount of active component, other preparation conditions on the catalytic effect and the structure of Z/CLM materials. Using the optimum Z/CLM material prepared on best conditions as a catalyst to investigate the treatment conditions of direct purple D-BL in CWPO. For instance, the addition amount of H2O2, the concentration of the solution, solution pH, treating temperature and processing time. And the tests of the simulation fluidized bed and regeneration were also carried, finally a simple discussion had been done on the reaction mechanism.The results showed that:(1) The zeolite catalysts loaded Cu, La, Mo, Zr and Fe had better catalytic activity in CWPO. And the optimum conditions of the material preparation were natural zeolite 60-80 mesh count, gradually dipping with salt-mixture solution Cu:La:Mo=0.5:0.5:0.2 (mol·L-1) by solid-to-liquid ratio 1:1, calcinated at 600℃for 0.5h. (2) Z/CLM materials had better removal efficiency in CWPO, the decolorization rate of direct purple D-BL can reach 95.15% under the optimum condition, H2O2 8.33 ml·L-1, the concentration of NaCl 5.84 g·L-1, pH 7.10, temperature 35℃, the processing time 5h. Moreover, the temperature of wastewater and the concentration of NaCl had promotion to the removal efficiency, and the material had a higher removal rate in acidic and weak base pH conditions.(3) Besides, dynamic fluidized bed experiment indicated the removal ability to direct blending purple D-BL was 37.82 mg·g-1, and recycling experiments showed that the regeneration of the material was poor.(4) Reaction mechanism of catalytic wet peroxide oxidation evinced that the reaction was a reaction of HO·. |
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