Study On The Catalytic Ozonation Of Methylene Blue With Activated Carbon Functionalized By Fe-Mn Binary Oxides

As typical industrial wastewater,printing and dyeing wastewater contains refractory pollutants,which is cancer-causing.Catalytic ozone technology can effectively treat it and elevate the quality of effluent,reaching the goal of reusing water.However,the separation and recovery of catalyst is a major problem in its practical engineering.In this paper,powdered activated carbon functioned by magnetic iron-manganese oxides was prepared as a novel catalyst,it treating methylene blue solution which simulated the printing and dyeing wastewater was studied to suggust a technology that degradating organic matter and being magnetically reclamied quickly.Modified activated carbon with three loading ratios was prepared by coprecipitation method and characterized by BET specific surface area test,scanning electron microscope analysis,EDS energy spectrum analysis,X-ray diffraction analysis,infrared spectrum analysis,X-ray photoelectron spectroscopy analysis,VSM magnetic intensity measurement and Zeta potential analysis.While its magnetic separation,metal ion leaching rate and reuse efficiency were studied in detail.After comparing the adsorption removal and catalytic ozone degradation of methylene blue,the optimum load ratio was determined to be 1:1,and the conditions and mechanism of adsorption and catalysis were studied more deeply.In the adsorption experiment,the adsorption behavior was analyzed by adsorption kinetics,adsorption isotherm and adsorption thermodynamics.And the optimum adsorption experimental conditions were determined by exploring the influencing factors of time,including temperature,initial concentration,p H,catalyst dosage and salinity.The adsorption mechanism was inferred according to the characterization results.In the catalytic ozone experiment,the synergistic effect of adsorption,oxidation and catalysis was studied with different kinds of catalysts and different levels of ozone dosage.The best catalytic experimental conditions were determined under the influence of different reaction time,different p H environment,different dosage and salinity.Moreover,methyl orange and rhodamine B were used to expand the catalytic effect of catalysts for different dyes.Finally,the mechanism of catalytic ozone was inferred by salinity,group closure and free radical on the basis of adsorption mechanism.The characterization results show that iron and manganese oxides are successfully supported on activated carbon.The modified activated carbon showed excellent efficiency in the adsorption and removal of methylene blue and catalytic ozone degradation.When the concentration of methylene blue was 300 mg/L and the dosage of activated carbon was 0.6 g/L,the removal rate can reach 97%,and the maximum adsorption capacity was 467.22mg/g.When the concentration of methylene blue was 500 mg/L,the dosage of activated carbon was 0.6 g/L,and the maximum adsorption capacity was 518.20 mg.After putting into 2mg/min ozone,the decolorization rate of 30 min in the catalytic ozone system can reach 100%,the mineralization rate is 88%,and the effluent can meet the "Textile dyeing and finishing Industry reuse Water quality Standard"(FZ/T01107-2011).In the ozone system alone,the decolorization rate can be increased by up to 41%,and the mineralization rate was only 66%.The removal rate of 500mg/L methyl orange treated by the same system was up to 40% higher than that of ozone alone.In the process of adsorption and catalysis,the leaching rate of metal ions of modified activated carbon is low,and the removal rate can reach 77.5% after 5 times of recycling.The adsorption of methylene blue by modified activated carbon accords with the pseudo-second order kinetic and Redlich-Peterson isotherm model,and the adsorption is faster in alkaline environment.The catalytic ozone process accords with the pseudo-first-order kinetics and has significant degradation effect in the range of p H=3～10.Salinity has little effect on the adsorption and catalytic process,indicating that the system has a wide range of adaptation to water quality,which can significantly improve the utilization rate of ozone and maintain efficient removal efficiency.This is due to its large specific surface area,rich surface groups,and good catalytic performance of iron and manganese as transition metals,which can adsorb the ozone and methylene blue on the surface for catalytic oxidation,and catalyze ozone to produce a large number of free radicals for rapid degradation of organic compounds.In summary,the novel efficient ozone catalyst with magnetic reclaiming performance prepared by cheap raw materials and simple synthesis method has engineering value for advanced treatment of printing and dyeing wastewater.