Study On The Degradation Of Azo Dye Wastewater By Ultrasonic Assisted Ball Milling

Batch mode experiments were conducted to study the effect of process parameters on the degradation of azo dyes by ultrasonic assisted ball milling and the mechanism of reaction.By changing the initial concentration of azo dyes,the ratio of ball to material,the ultrasonic frequency,the amount of iron powder added,the initial pH value,the concentration of hydrogen peroxide and the type of gas,to explore the effect of process parameters on degradation rate of azo dye in aqueous solution by ultrasonic ball milling.Removal of azo dyes in water by contrast ultrasonic milling,ultrasonic irradiation and ball milling.The samples were analyzed by UV spectrophotometer,fluorescence intensity,conductivity and total carbon content(TOC),Reaction precipitate were detected by X-ray diffraction and specific surface area.to explore the mechanism of reaction.The experimental results show that the initial concentration and the initial pH value are smaller,the degradation rate of azo dyes is faster,The suitable initial concentration is 100mg/L,the best ratio of ball to material is 1.333kg/L,suitable for the frequency is 40kHz,the initial solution pH=3,the concentration of H2O2 is 300mg/L and put into the air.Under the optimum process parameters,the degradation rate of methyl orange and congo red reached more than 99%at 4min and 8min.The removal rate of total carbon in solution was 80%at 8min.The degradation rate,the strength of hydroxyl radical and the conductivity of the azo dyes degradation were ultrasonic ball>milling>ultrasonic.Fe3O4,FeO(OH)and Fe were detected in the reaction sediments,And the specific surface area is 90.257 m2/g,the average particle size is 154.54nm,Based on the above results,there were a large number of hydroxyl radical Fe2+ and Fe3+ were producted in the degradation of azo dyes by ultrasonic ball milling.Azo dyes were in contact with the ball surface and zero valent iron by impact spalling,The redox reaction occurs under the action of hydroxyl radical,forming Fe3O4 and FeO(OH)and adhere to the surface of the ball,and spalling by the mechanical effect of ball impact and ultrasonic,and fresh surface was provided.The new sxurface of iron ball reacted with azo dyes.In addition,Fe2+ produced by the reduction of zero valent iron can react with the H2O2 produced in reaction and added,The rate of degradation is accelerated and the process will continue until the azo dye is completely degraded.