Study On Degradation Of Safranine T Dye Wastewater By Three Fenton Systems

Dye wastewater is a kind of common industrial wastewater.As a large printing and dyeing country,China needs to treat a large number of dye wastewater every year.Due to the complexity of dye wastewater,it is difficult to treat it completely by using conventional waste treatment methods.Various physical,chemical and biological methods are used to treat dye wastewater.Fenton has been widely used in many wastewater treatments due to its unique advantages,such as simple operation,only addition of H2O2 and FeSO4,rapid reaction,high degradation efficiency,treatment of most of the refractory pollutants and so on.In addition,more and more attention has been paid to the improved Fenton methods such as electro-Fenton method and UV/Fenton method which derived from the traditional Fenton method.Safranine T is a kind of biological stain,acid-base indicator and redox indicator,which is widely used in various fields.When a large amount of Safranine T is discharged into the natural environment without any treatments,it will have a huge impact on the water landscape and physical and chemical properties.Therefore,the study of the degradation of Safranine T by Fenton can provide some theoretical guidance for its engineering application.In this paper,Safranine T was taken as the processing object,the reaction kinetics and various influencing factors in the degradation process of traditional Fenton method,electro-Fenton method and UV/Fenton method were discussed,and optimum reaction conditions were obtained in each Fenton system The main contents and results of this paper are as follows:(1)The traditional Fenton method was used to degrade Safranine T.The effects of pH,H2O2 dosage,FeSO4 dosage,and substrate concentration on the removal rate of Safranine T were mainly investigated.When 100 mL of Safranine T solution(100 mg/L)was treated,the optimum reaction conditions were 0.9 mL of 0.1 mol/L H2O2,2 mL of 0.01 mol/L FeSO4 and the pH value of 3.The removal rate of Safranine T reached 98%after 30 min.The reaction kinetics was investigated,and the reasults showed that the degradation of Safranine T by traditional Fenton method accords with the second-order kinetics equation.(2)The electro-Fenton method was used to degrade Safranine T.The effects of pH,FeSO4 dosage,current density and substrate concentration on the removal rate of Safranine T were mainly investigated.When 100 mL of Safranine T solution(100 mg/L)was treated,the optimum reaction conditions were 3mL of 0.01mol/L FeSO4,the current density value of 20 mA/cm2,and the pH value of 3.The removal rate of Safranine T reached 83%after 120 min.The reaction kinetics was investigated,and the reasults showed that the degradation of Safranine T by the electro-Fenton method accords with the second-order kinetics equation.(3)The UV/Fenton method was used to degrade Safranine T.The effects of pH,H2O2 dosage,FeSO4 dosage,light intensity and substrate concentration on the removal rate of Safranine T were mainly investigated.When 100 mL of Safranine T solution(100 mg/L)was treated,the optimum reaction conditions were 0.9 mL of 0.1 mol/L H2O2,1.2 mL of 0.01 mol/L FeSO4,and the pH value of 3.The removal rate of Safranine T reached 100%after 20 min.The reaction kinetics was investigated,and the reasults showed that the degradation of Safranine T by the electro-Fenton method accords with the second-order kinetics equation.(4)Through the comparative study on the degradation of Safranine T by three kinds of Fenton systems,it was found that the degradation rate and removal rate of Safranine T were the same,and the order was light assisted Fenton system>traditional Fenton system>electro-Fenton system.