Research On The Mechanism And The Optimization Conditions Process Of Oxidative Degradation Of Aniline By Fenton’s Reagent

Aniline is a highly toxic and unreadily biodegradable material. How to deal with aniline wastewater has become imperative.Experimental studies have shown that Fenton oxidation is a kind of promising technology in wastewater treatment,because of the strong oxidizing reaction conditions and not easy to produce secondary pollutants. In order to enhance the effect of Fenton oxidation should determine the optimal reaction conditions. Fenton reaction is essentially a redox reaction. As an important parameters of redox reaction, oxidation reduction potential is able to indicate the process of Fenton reaction in theory.Therefore, it has an important directive significance of systematically analyzing the mechanism of the influencing factors in the Fenton reaction to achieve online control of Fenton oxidation process.In this paper aniline was chosen to be the object which was treated by Fenton oxidation technology. The impact of factors such as p H, the mole ratio and absolute dosage of H2O2/Fe2+on the removal efficiency of aniline and COD were studied and the optimum oxidation conditions were investigated. With the change of the main factors during the reaction, the change law of oxidation reduction potential(ORP) was found out after filtering out the main redox couple of Fenton reaction system.Furthermore,we can use ORP to control the Fenton reaction process. The paper has studied and explored the reaction mechanism by detecting intermediate of aniline Degradation.The keys in this paper are as follows:(1) The wastewater containing aniline with the concentration of 100mg/L was treated by Fenton’s reagent with the optimal reaction condition(p H=3.3,n(H2O2)/n(Fe2+) =10, c(H2O2)=12.5mmol/L, c(Fe2+)=1.25mmol/L). After 60 min under this condition, the reaction process can achieve to the best result, and the removal efficiency of phenol and COD can respectively be 87.73% and 67.12%.(2) Fe3+/Fe2+is the most important redox couple of Fenton oxidation system that determine directly the oxidation reduction potential during the Fenton reaction. The factors such as p H, H2O2 dosage and mole ratio value of H2O2 and Fe2+ can change the ORP value and its peak value by influencing transformation of iron ions during reaction. The effect of H2O2 dosage is the most significant.According to Fenton reaction, the degree of organic pollutants degradation can be indicated by the variation of ORP.(3) The degradation intermediates of aniline can be tested by GC-MS.On this basis, the degradation mechanism of aniline can be discussed.We can find that the initial production by degradating aniline is mainly parahydroxyaniline.The benzene ring can be ruptured and transform into butane diacid with increasing the reaction time, which is consistent with the classical theory of hydroxy. The intermediate production can be mineralized into carbon dioxide and water when the addition of Fenton reagent is large.