Oxidation of Safranine T in Aqueous Solution Using Fenton's Reagent: Involvement of an Fe(III) Chelate in the Catalytic Hydrogen Peroxide Oxidation of Safranine T

Abstract

This study addresses the chemistry and kinetics of oxidation of a basic dye, Safranine T (C. I. Basic Red 2) by the classic Fenton's reagent (Fe2+ and H2O2). The kinetic study suggests that the chemistry involved in this system differs to some extent from that reported for the classic Fenton's chemistry in aqueous solution. Thus, participation of an Fe(III)−organic complex in the catalytic decomposition of H2O2, thereby producing an active oxidant, seems to be a step in the oxidation mechanism. Stoichiometric measurements of the hydrogen peroxide consumption per mole of Fe2+ used, poor oxidation of dye by the combination of Fe3+ and H2O2, and the formation of a shoulder at around 385 nm suggest a possible formation and participation of an Fe(III)−organic complex. The oxidation data indicates that Safranine T can be most effectively oxidized at a pH of around 3. The Fe(III) chelate catalyzed peroxide oxidation of Safranine T follows pseudo-first-order kinetics. The activation energy for the Fe(III) chelate catalyzed peroxide oxidation of the dye was determined to be 75.91 kJ mol-1.