Degradation of Para-Phenylenediamine in Aqueous Solution by Photo-Fenton Oxidation Processes

Abstract

In this research Photo-Fenton Oxidation of Para-Phenylenediamine (PPD) in aqueous solution by UV/Fenton’s reagent (Fe²⁺ and H₂O₂) was investigated. Experiments were conducted in a batch reactor, at pH 3.5 and at 25°C with a source of UV-C light. The effects of different reaction parameters such as initial PPD concentration, pH of the solution, ferrous concentration, Hydrogen peroxide concentration, on the oxidative degradation of PPD were measured. Final concentration of PPD and COD of the solution after treatment were determined to know degree of degradation of the compound. Iron source used for photo-Fenton’s oxidation were Ferrous Sulphate (FeSO4.7H2O).The optimum conditions established by Fenton’s oxidation without UV, were considered for this investigation. Only the maximum removal conditions were tried with the UV for reaction time of 3 hours. The results showed that under optimum experimental conditions, the pH 3.5, 50 mg/L H2O2, 3 mg/L Fe²⁺and UV reaction time of 3 hours, the initial concentration 10 mg/L of PPD was reduced by 71.20% with 65.89% COD removal. Likewise the removal efficiencies for PPD concentration of 20, 30, 40 and 50 mg/L keeping the same proportion of H₂O₂and Fe²⁺dosage (with ratios of PPD:Fe²⁺:H₂O₂::10:1:16.7) were investigated and the results showed, PPD removal were 65.10, 61.23, 58.34 and 54.26% and COD removal was 61, 54, 52 and 50.32% respectively. From the results obtained it can be concluded that Fenton’s reagent favours the lower concentration of Phenylenediamines and UV-C assisted photo-Fenton showed that the photo-Fenton process was very effective than the normal Fenton process.

Keywords: Para-Phenylenediamine; COD; UV-C light; Fenton’s reagent; Oxidation