Advanced Oxidation of Direct Red (DR 28) by Fenton Treatment

Advanced oxidation of Direct Red 28 (DR 28) in aqueous solution by Fenton's reagent using FeSO4 as source of Fe (II) was investigated. Effects of the dyestuff and the reagent concentrations (H2O2 and Fe (II)) on oxidation of the azo dye were investigated by using a Box-Behnken statistical experiment design and the surface response analysis. Degradation and mineralization (conversion to CO2 and H2O) of the azo dye by Fenton treatment was evaluated following total organic carbon (TOC) and color removal. Dyestuff removal increased with increasing H2O2 and Fe (II) concentrations up to a certain level. Fe (II) had a more profound effect on dyestuff removal as compared to H2O2. Complete color removal (100%) was achieved in 5 minutes. However, mineralization of the dyestuff took 15 minutes and required higher doses of H2O2. Percent color removal was always higher than TOC removal indicating formation of colorless organic intermediates. Optimal H2O2/Fe (II)/dyestuff ratio resulting in the maximum TOC (99.2%) and color (100%) removals was found to be 1450/78/235(mg L-1).