Study On Photodegradation Of Printing And Dyeing Wastewater With Multiple Metal-doping Modified ZnO/ZSM-5

This paper mainly studies the degradation effect of the load photocatalyst?Zn O/ZSM-5?on rhodamine B and multiple influencing factors of photocatalytic process.The effects of different doping types and proportions of materials on the degradation rate of rhodamine B were investigated by doping with noble metal Ag and transition metal Fe and Cu.The paper has not only research on the photocatalytic performance of different materials under different light sources,such as ultraviolet,visible,simulated sunlight and sunlight have been carried on,but also the cooperative degradation effect on rhodamine B under the photocatalytic oxidation with H ₂O₂chemical oxidation.In addition,the paper also studies the properties of recycled materials and tries to recycle the modified materials by using the external magnetic field.The main conclusions are as follows:?1?Scanning electron microscope?SEM?,transmission electron microscope?TEM?,energy dispersive spectrometer?EDS?,X-ray diffraction?XRD?,and N₂adsorption-desorption isothermal curve were adopted to characterize the morphology and structure of different m aterials,and the results show that particles of the multiple-doped modified material are small and uniformly distributed,basically without reunion phenomenon.Besides,the material has high purity,good crystallinity and less impure peaks.These mat erial own mesoporous structure and their adsorption-desorption isothermal curve present type?with an H3 hysteresis loop.The pore size distribution of different samples is uniform and broad.Due to the low doping amount or the entrance into the photocata lyst lattice,there is no obvious characteristic peak of doping element,which indicates the success of material modification.?2?Explore the photocatalytic performance of the Zn O/ZSM-5 under a 20W ultraviolet germicidal lamp,and we finally selected the optim al experiment condition as:0.1 g/L of material dosage,5 mg/L initial concentration of rhodamine B,p H 7,20W ultraviolet sterilization lamp and 0.1 m L?mass concentration of 6 g/L?of H ₂O₂addition.Under the optimal experimental conditions,the degrada tion rate of rhodamine B reaches 99.8%in two hours.?3?The optimal doping proportion of Ag,Fe and Cu was 5%,3%and 0.1%respectively?according to the mole ratio of Zn O?.Under the simulated sunlight?xenon lamp?and the sun,the decolorizing effects o f the following four photocatalytic materials on rhodamine B printing and dyeing wastewater were ranked:3%Fe-0.1%Cu-5%Ag-Zn O/ZSM-5>3%Fe-Ag-Zn O/ZSM-5>5%Ag-Zn O/ZSM-5>Zn O/ZSM-5,namely doping modification methods broaden the area of the spectral response of the material to the visible light region,while the material absorption occurs obvious red shift and light quantum efficiency improved significantly.By using the 3%Fe-0.1%Cu-5%Ag-Zn O/ZSM-5,the degradation rate of rhodamine B in2h under the xenon lamp and the sun was 97.7%and 96.24%,respectively.The study of photocatalysis-H₂O₂ chemical oxidation cooperative treatment of dye wastewater obtains good decolorizing e ffect,and when 0.1 m L of H₂O₂?mass concentration of 6g/L?serves as plus antioxidant,the multiple-doped modified material can degrade98.29%of rhodamine B in 90 minutes under the simulated sunlight irradiation.?4?The material recovery rates in the f irst three times were 95.16%,97.04%and95.83%,respectively?in the sunlight?.And the modified photocatalytic materials of3%Fe-0.1%Cu-5%Ag-Zn O/ZSM-5 recovered from the first three times can still degrade 94.17%,89.01%and 80.82%of rhodamine B for 4h in the sunshine,respectively.The catalyst was not inactivated during the whole reaction process,and its stability and dispersibility were better.After ultrasonic cleaning and drying,the catalyst could still be used as a good photocatalytic material.T he multiple-doped modified material has weak magnetism,but it is not possible to use the external magnetic field to realize the recycling of all the materials.