Preparation Of NZVI/AC By Electrodeposition And Study On Decolorization Performance Of Azo Dyestuffs

China is the largest country in the textile printing and dyeing industry,accounting for 70% of the world's dye production.A large amount of printing and dyeing wastewater that has not been treated or substandard has been discharged into rivers and lakes every day,which poses a serious threat to the water environment.Nano zero-valent iron is an emerging and highly efficient environmental remediation technology that has been widely used in the treatment of heavy metals,halogenated compounds,and nitrates.As an emerging research field,the preparation method of nano-zero-valent iron has been continuously innovated in recent years,and the application range is becoming wider and wider.At present,there are many costly preparation methods,which are only suitable for a small amount of preparation in the laboratory.In this paper,based on electrodeposition method with simple equipment,convenient operation and extensive application basis,the activated carbon is used as the carrier electrode to prepare the zero-valent iron/activated carbon(nZVI/AC)through the preparation process.The parameters of the deposition fluid and the current parameters were optimized,the optimal preparation conditions were determined,and the nZVI/AC prepared under the conditions was characterized and analyzed,and used for the decolorization performance of the azo dyes and the kinetics study.In the experimental study of the influence of electrodeposition parameters on the properties of nZVI/AC,the degradation rate of methyl orange(MO),the indicators of sedimentation and the indicators of the system were used as the evaluation system.The orthogonal test and analytic hierarchy process were used.The influence of different deposition fluid parameters on nZVI/AC,and the optimum deposition fluid parameters are: FeCl2�4H2O concentration is 400g/L,pH value is 2.0,solution temperature is 40�C,saccharin,sodium lauryl sulfate and chlorination The amounts of manganese added were 1.0 g/L,0.05 g/L,and 30 g/L,respectively.In the experimental study of the effect of current parameters on the performance of nZVI/AC,the MO degradation efficiency,current efficiency,and mass ratio of iron to carbon were used as the evaluation indicators.The single factor effect test was used to optimize the current density of nZVI/AC for direct current preparation to be 3.0.A,the power-on time is 10 minutes.The characterization analysis of nZVI/AC prepared by electrodeposition under optimal conditions shows that the zero-valent iron successfully loaded on activated carbon by electro-deposition is floccular,with a monomer size of about 200 nm,specific surface area and total pore size.The volumes were 470.103 m2/g and 0.361 cm3/g,respectively.nZVI/AC has good decolorization effect on MO dye wastewater,and has a wide application range.The degradation mechanism is mainly based on reduction,adsorption and coagulation coprecipitation.The degradation rate increased with the increase of the initial concentration of MO,and decreased with the increase of reaction temperature,DO,coexisting substances Na2SO4 and CMC,and the degradation rate was the highest when the pH was neutral.The decolorization of MO dyes by nZVI/AC mainly follows the first-order exponential decay kinetics model,and the linear decay kinetic model follows the coexistence of CMC.