Abstract
The study evaluated the catalytic impact of surfactant micelles on the reactive azo dye degradation from a mixed azo dye-containing dyeing effluent (MDE) by the Fenton advanced oxidation process (AOP), focusing on the reaction kinetics and mechanism. The Fenton AOP has been used for organic pollutant degradation for the last many decades; due to the requirement of high concentrations of Fenton reagents (Fe(2+), H(2)O(2), H(2)SO(4); pH: 2.5 to 4) and high temperatures (323 to 353 K), the process lost reality for real industrial dyeing effluent treatment. The objectives of the study were to enhance the dye degradation reaction rate from dyeing effluents, minimize the concentrations of Fenton reagents, and lower the process temperature, thus making the process suitable for industrial dyeing effluent treatment. The result of the research exposed a significant improvement of the azo dye degradation rate from a mixed azo dye effluent by the catalytic role of micelles through Fenton AOP. The result of the azo dye degradation rate from MDE was found to be 62.43% in aqueous <73.43% with CTAB micelles <81.27% with SDS micelles <93.34% with TX-100 micelles, under identical reaction conditions after 60 min. The rate constants in aqueous and in micelles (k (w) and k (m)), binding constants (K (S) and K (F)), activation parameters, activation energy (E (a)), activation entropy (ΔS), activation enthalpy (ΔH), and Gibbs free energy (ΔG) were evaluated and discussed in light of the reasons for the catalytic effect of micelles in the azo dye degradation from MDE. The micellar catalytic dye degradation reaction rates were explained by the pseudophase-mass-action model. A complete reaction mechanism of azo dye degradation initiated through the dissociation of the azo bond (-NN-) by Fenton AOP in aqueous and micellar systems has been presented.