Synergistic Degradation Of Dye Wastewater By Ultrasound-BiFeO₃-H₂O₂ Fenton-like System

With the rapid development of the dye industry,a large amount of dye wastewater is discharged,which not only pollute the environment,but also harm the survival of aquatic organisms and people's health,and thus the treatment of dye wastewater has become a major project in the treatment of water pollution.Dye wastewater has many characteristics,such as consuming a large amount of water,high chromaticity,poor biodegradability,high content of toxic organic and complex composition as well,and so on.The traditional treatment method is difficult to decompose it thoroughly.Advanced oxidation technology can completely decompose organic pollutants by hydroxyl radicals ·OH which produced in the reaction process,and it has the characteristics of strong oxidative decomposition ability,indiscrimi-nately and thoroughly degrade the dye,which has become a hotspot to deal with dye wastewater in recent years.By the cavitation effect,Ultrasound oxidation technology can indiscriminately degrade the organic pollutants into environmentally friendly inorganic molecules,such as CO2,H2O,etc.,but it takes a long time to complete degradation of organic pollutants only with ultrasound.The traditional Fenton technology has the advantages of high efficiency and complete reaction,but it needs the PH value of the system to be 3.0 or so,and each cycle needs to add high molar concentration of ferrous ions and oxidants,due to the addition of large amounts of ferrous ions,the subsequent need to deal with a large number of iron mud.This method is lack of reusability.Based on these problems,the ultrasound-BiFeO3-H2O2 Fenton system was constructed.The methyl orange and rhodamine B simulated dye wastewater were used as the research object.The treatment results were carried by degradation rate and UV absorption spectrum.The main contents are as follows:(1)Preparation of bismuth ferrite(BiFeO3)particles.In this paper,BiFeO3 was prepared by hydrothermal method,which can catalyze H2O2.The structure and morphology of the BiFeO3 were characterized by XRD and SEM.The morphology of BiFeO3 was complete and uniform.(2)Ultrasound-BiFeO3-H2O2 system degrade the methyl orange simulated wastewater.The degradation effects of methyl orange is compared with different method,which is ultrasound,BiFeO3-H2O2 or both of them.The results show that the ultrasound-BiFeO3-H2O2 system has a good synergistic effect on the degradation of methyl orange,and the degradation rate can reach at 98.9%by 30 min.Then,the effect of addition of free radical scavenger isopropanol alcohol on the degradation of methyl orange was investigated.The results showed that the addition of isopropyl alcohol decreased the degradation effect,which indicated that the degradation process was mainly oxidized by free radicals.Finally,the influential factors of methyl orange simulated wastewater were studied by ultrasound-BiFeO3-H2O2 system.It was found that the optimum frequency of the treatment of methyl orange was 203.9 kHz,and the degradation rate was increased with the increase of ultrasound power.The degradation rate increased with the increase of BiFeO3 dosage.On the contrary,the degradation rate decreased with the increase concentration of methyl orange.The optimum pH value of the reaction system was 5.(3)Ultrasound-BiFeO3-H2O2 system degrade the rhodamine B simulated waste-water.The degradation effects of rhodamine B is compared with different method,which is ultrasound,BiFeO3-H2O2 or both of two.The results show that the ultrasound-BiFeO3-H2O2 system has a good synergistic effect,and the effect is better than that of the superposition of the two,and the degradation rate can reach at 95%by 60 min.Then,the degradation of rhodamine B was studied by adding 10?l of isopropanol alcohol.The results showed that the addition of isopropyl alcohol decreased the degradation effect,which indicated that the degradation process was mainly oxidized by free radicals.Finally,the influential factors of rhodamine B simulated wastewater were studied by ultrasound-BiFeO3-H2O2 system.The results show that the degradation rate of rhodamine B decreased greatly with the increase concentration of rhodamine B,and increased with the increase of BiFeO3 dosage.There is a best dosage of H2O2 by 1%.The degradation rate increases with the increase of the frequency and power of ultrasound.The optimum pH value of the reaction system is 5.