Experimental Study On Treatment Of High Concentration Wastewater From Dye Intermediate By Catalytic Wet Peroxide Oxidation

As a major producer of dyes in China,the annual output of dyes and dye intermediates is far in the forefront of the world.The wastewater produced by the dye intermediate industry has the characteristics of high concentration of pollutants,high chroma,poor biodegradability and biological toxicity,and is one of the industrial wastewaters that are difficult to treat.As a kind of advanced oxidation method,catalytic wet peroxide oxidation technology has wide application in the treatment of high concentration refractory organic wastewater due to its simple operation,mild reaction conditions,high treatment efficiency and low secondary pollution.The key to the treatment of high concentration wastewater by catalytic wet peroxide oxidation is the preparation of the catalyst.In this paper,the high concentration T-acid wastewater produced in the production of dye intermediate H-acid is taken as the research object.Three active components with high catalytic activity are selected from the common transition metals such as Fe,Mn,Cu,Zn and Ni.The effects of the composition and proportion of the active components,the composition of the support and the preparation conditions of the catalyst on the activity of the catalyst are studied.The catalyst was prepared by excessive immersion method,and the loading of active components was promoted by water bath heating.The experimental results show that the catalyst prepared with active component of Cu:Ni=1:1?molar ratio?has good catalytic activity,and the best carrier is the molecular sieves.Through the optimization of various factors in the preparation process,the optimum preparation conditions of catalyst were determined as follows:the concentration of active component was 0.8mol/L,the immersion temperature was 80?and the loading time was 4 h.After the reaction was completed,the solution was cooled and filtered,the solid catalyst was dried in a constant temperature drying box for 1 h,and then baked in a muffle furnace at 400?for 5 hours,and naturally cooled to obtain a desired catalyst.The catalytic oxidation degradation of T-acid wastewater was carried out by using the catalyst prepared under the above optimal conditions with H₂O₂ as oxidant.The effects of different experimental conditions on the degradation efficiency of T acid production wastewater were studied.The optimum treatment conditions were as follows:the initial pH was 4,the dosage of hydrogen peroxide is 25 mL,the catalyst dosage was 3 g,the reaction temperature was 80?,the reaction time was 75 min,and the decolorization rate reached 84.88%and the COD removal rate reached 69.07%.The experimental results show that the prepared catalyst has a good degradation effect on high concentration T-acid wastewater,which can provide reference for the treatment experiment or industrial application of high concentration dye intermediate wastewater.A series of comparative experiments were carried out to study the degradation mechanism of T-acid production wastewater.The degradation is the result of the interaction of adsorption and oxidation,but the main effect is oxidation,and adsorption only accounts for a small part,and the main active group in the oxidation was hydroxyl radicals.In addition,the stability and repeated service life of the catalyst were also studied.The results showed that drying at 105?and burning at 300?had little effect on the activity of the catalyst after regeneration,and it could be used as a regeneration method of the catalyst.The prepared catalyst has good degradation effect on T acid production wastewater after repeated use for 4 times.When the catalyst is reused for four times,the removal rate of COD is still above 60%,and the decolorization rate can be kept above 75%.And then reused,the catalytic effect of the catalyst decreases significantly.At this time,the catalyst needs to be replaced.