Kinetic Study of Methyl Orange Azo Dye Discoloration by Fenton Processes in the Presence of Di-hydroxybenzenes and Gallic Acid

Abstract

The present work evaluates the influence of distinct phenolic compounds individually (dihydroxybenzenes and gallic acid) on the discoloration kinetics of methyl orange azo dye by Fenton processes (Fe 2+ /H2O2, Fe 3+ /H2O2). The treatments were performed with iron salts, H2O2, in the absence and presence of six phenolic compounds. Based on the discoloration data from previous study of our group, the 1 st and 2 nd order kinetic models were analyzed, as well as the alternative BMG model. It was found that the phenolic compounds accelerate the reactions promoting larger percentages of dye discoloration. In general, the reactions in the presence of phenolic compounds fit well to the 1 st kinetic model, whereas for the reactions without these mediators only the BMG model was appropriate.