Preparation Of Nano-Manganese Dioxide And Its Catalytic Degradation Of Methylene Blue

Printing and dyeing wastewater usually has high organic matter concentration,complex chemical composition,large physical color,poor biodegradability,and large side effects.Such water treatment is difficult,complicated,difficult to process by biological means,and high in processing cost..Based on these factors,a material is prepared to reduce the process flow and solve the problem of difficult biodegradation.Simple and efficient treatment of printing and dyeing wastewater is the experimental purpose of this experiment.In this paper,nano-manganese dioxide,5%Ni-doped nano-manganese dioxide and 5%Fe-doped nano-manganese dioxide were prepared by redox method and hydrothermal method,and catalytic degradation experiments were carried out with methylene blue as the target pollutant in printing and dyeing wastewater.the study.The specific research contents are as follows:(1)Using manganese permanganate and manganese sulfate as raw materials,nanometer manganese dioxide was prepared by redox method and hydrothermal method.The products were characterized and analyzed by scanning electron microscopy(SEM),X-ray diffractometry(XRD),specific surface area and pore size analysis(BET).The removal of methylene blue by nanometer manganese dioxide was also investigated.The results showed that the removal rate of methylene blue by nano-manganese dioxide prepared by redox method reached 87.90%under the condition of dosage of 120mg,initial p H=7.0 and reaction temperature of 25°C.Nano-manganese dioxide prepared by hydrothermal method The removal rate of methylene blue was 60.90%.The experiment explored the effect of sample dosage,p H and temperature on the removal efficiency.The results showed that the highest removal rate was 88.09%after 3h at initial p H=7.0,and the final removal rate was 93.96%after 3h reaction with the dosage of manganese dioxide being 150mg.The reaction temperature was removed at 55°C.The highest rate is 94.84%.(2)Preparation of 5%Ni-doped nano-manganese dioxide and 5%Fe-doped nano-manganese dioxide.Characterization and analysis were performed by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and specific surface area and pore size analysis(BET)techniques.The effect of the dosage,initial p H and reaction temperature of the reaction sample on the removal of methylene blue was studied by using methylene blue as a simulated pollutant.The experimental results show that when the dosage is 20mg after 3h reaction and the reaction p H=7.0,the removal rate of methylene blue by 5%Ni-doped nano-manganese dioxide is optimal,and the removal rate reaches99.57%.When the dosage is When 20mg,reaction p H=9.0,the removal rate of methylene blue by 5%Fe-doped nano-manganese dioxide was optimized,and the removal rate after99h was 99.50%.(3)Adsorption kinetics and mechanism analysis were carried out on nanometer manganese dioxide,5%Ni-doped nano-manganese dioxide and 5%Fe-doped nano-manganese dioxide to remove methylene blue simulated printing and dyeing wastewater.The quasi-first-order and quasi-secondary adsorption kinetics simulations were carried out respectively.After fitting,the experimental data of the three samples were fitted to the second-order kinetic curve with a higher degree of fitting,and the fitting correlation coefficients were all above 0.99.,up to 1.0000.At the same time,the fitting study of the catalytic reaction kinetics was carried out.The fitting results showed that the three materials had a good linear fit to the first-order reaction kinetics of the Langmuir-Hinshelwood equation model,and R~2 was above 0.95.Based on the oxidation and catalytic properties of manganese dioxide itself,the doping of Fe ions and Ni ions changed the morphology of manganese dioxide,which significantly improved the activity and catalytic efficiency of manganese dioxide in degrading methylene blue under visible light.Based on the characterization and experimental results,it is considered that the effective doping of Fe and Ni ions achieves the purpose of efficiently degrading methylene blue simulated printing and dyeing wastewater.