Using Oxidation-reduction Potential Control Fenton Oxidation For Phenol Wastewater Treatment

Phenols is a organic substances with high content in industrial wastewater and not easy to deal with. Experimental studies have shown that Fenton oxidation as an adva-nced oxidation method have a broader prospect, because of the strong oxidizing reaction conditions and not easy to produce secondary pollutants.In the Fenton oxidation reaction, the hydroxyl is the reaction of H2O2 with Fe2+, so, the dosage of H2O2 is to determine the Fenton oxidation for the wastewater treatment. However, in the reaction with the organic matter concentration different, the H2O2 dosage is different, which makes the practical application of Fenton reaction in a certain limitations. Fenton reaction is a redox reaction. Oxidation-reduction potential (ORP) is the important factor to determine the direction and extent of redox reactions. So, in the Fenton reaction, the degradation of organic matter is the process of oxidation-reduction potential (ORP) change.In this paper phenol wastewater was treated by fenton oxidation reaction to study main factors and find the optimum conditions in the reaction. Then, with the change of main factors, the experiment find out the law of oxidation-reduction potential (ORP) change and research the reasons .Then, the data was used to establish the mathematical model. Finally, the mathematical model was used to control the Fenton reaction for phenol wastewater treatment. The keys in this paper are as follows:(1)The phenol wastewater with the concentration of 100mg/L is treated by Fenton reaction with the reaction conditions are pH= 3, c(H2O2)= 15mmol/L, n(FeSO4)/n (H2O2)=0.1. After 30min, the reaction can reach the best results, CODCr removal rate of over 90%. The impact of the various parameters for the reaction is as follow relationship:the dosage of H2O2> n(FeSO4)/ n(H2O2)> pH value.(2)To study ORP value changes in different reaction conditions. The dosage of H2O2, n(FeSO4)/n(H2O2)with the oxidation-reduction potential (ORP) maximum value have the positive correlation. Initial CODCr value and oxidation-reduction potential (ORP)maximum value have the inverse relationship. The change of oxidation-reduc- tion potential (ORP) mainly is dued to the Fe2+ and Fe3+ concentrati-on ratio.(3)Obtain the following mathematical model of the formula: [CODCr]= 1833.28 +11.125 [H2O2]-3.51ORPMAX; [H2O2]opt= 0.0163[CODCr]+11.575. The formula R2 values are more than 0.96. Using the mathematical model control the Fenton oxidation of phenol wastewater treatment. With the increasing concentration of phenol, the removal rate could reach over 70%. The difference of initial CODCr value can be forecasted within 50mg/L.