Preparation Of Sludge Catalysts And Application In Decoloration Of Printing And Dyeing Wastewater

Catalysts were prepared by one-step method using dewatered sewage sludge andsesame as carrier, and transition metal compounds, copper nitrate as activecomponents of the catalysts. The active component concentration, solid-liquid ratio,calcination temperature and calcination time on catalytic properties were studied byorthogonal experiment and single factor experiment. The catalyst with strong catalyticproperties was prepared under the optimal conditions. Using NaOH modified theabove carrier, the modified catalyst with stronger catalytic properties was prepared.The physicochemical properties of the catalysts were characterized by scanningelectron microscopy, surface area analyzer and infrared spectrometer. The two kindsof catalysts were utilized in the oxidation of simulation azo dyes wastewater by H2O2.The effects of solution pH, the amount of catalyst and oxidant, the reactiontemperature and other factors on decolorizing effect were researched. On this basis,the COD and chroma degradation of the actual dyeing wastewater under the samemethods were studied. Results were as below:(1) Through the orthogonal experiment analysis, confirmed the impact of variousfactors on catalysts performance:calcination temperature> active ingredientconcentration> solid-liquid ratio> calcination time. From the analysis of single factorexperiment, when preparation conditions were controled with the concentration of theactive component Cu(NO3)2concentration of3mol/L, solid-liquid ratio of1:3,calcination temperature600℃, calcination time60min, the prepared catalyst had agood catalytic decoloring performance.(2) Modified the catalyst carrier with NaOH, the optimal conditions formodification were: modifier concentration0.8mol/L, modification temperature25℃,modification time6h. The modified catalysts had stronger catalytic properties.(3) The decolorization kinetics of simulation azo dyes wastewater using H2O2asoxidate and two kinds of sluge as catalysts corresponds to second-order kinetic model.The order of decolorization rate were: Reactive Black KN-B> Activity Yellow X-7G>Acid Yellow G> Acid Scarlet GR. During the reaction, the azo bond of the four azodyes fractured, the absorption peak in the visible region gradually decreased andeventually disappeared, and the color were removed. Uv of benzene, naphthalene ringabsorption peak gradually disappeared, indicated the benzene ring and naphthalene ring were opened and gradually degraded to small organic and inorganic molecules,eventually degraded to CO2and H2O.(4) Under the optimum reaction conditions, the decolorization rate of CAC,CACN catalysts catalyze H2O2oxidation actual dyeing wastewater were95%,98%,COD removal efficiency reached59.25%,69.65%. The two sludge catalysts had acertain degree of stability, which still had some removal effect after being used tentimes continuously.(5) The heterogeneous catalytic oxidation technology combined a variety ofmethods as adsorption, catalysis and oxidation to degrade wastewater, provide a newpath for embarrassed biodegradable wastewater.