Unveiling the effectiveness of the photo-Fenton process for the mineralization of textile dyes: A kinetic and thermodynamic study

Abstract

This investigation successfully demonstrates the effectiveness of the photo-Fenton process for degrading two common textile dyes, Acid Orange 8 (AO8) and Yellow 2 Green (Y2G), in aqueous solution. We systematically evaluated the critical operational parameters, identifying an optimal working pH of 3.0. The most effective reagent concentrations were found to be 50 mg/L for Fe²⁺ and 700 mg/L for H₂O₂, achieving remarkable degradation efficiencies of up to 99.24% for Y2G and 89.75% for AO8 within 60 minutes. Control experiments confirmed that the synergy between Fe²⁺, H₂O₂, and light is crucial, as omitting any single component led to negligible degradation. The process followed pseudo-firstorder kinetics, and thermodynamic analysis revealed negative Gibbs free energy values, confirming the reaction's spontaneity. Notably, the low activation energies calculated 24.90 kJ/mol for AO8 and 28.15 kJ/mol for Y2G indicate that the degradation proceeds with a low energy barrier. These findings collectively affirm the photo-Fenton process as a highly efficient and energetically favorable strategy for treating wastewater contaminated with these persistent dyes.