Kinetics study of chloride-activated peracetic acid for purifying bisphenol A: Role of Cl₂/HClO and carbon-centered radicals

Peracetic acid is an emerging oxidant and disinfectant for wastewater purification. In this study, we first developed a comprehensive and accurate model to elucidate the reaction mechanisms and simulate reaction kinetics of peracetic acid (PAA, CH₃C(=O)OOH) activated by chloride (Cl^–) based on experimental results and literature. A diversity of experiments methods (e.g., quenching experiments, probe compounds degradation, electron paramagnetic resonance (EPR) measurements) and kinetic modeling were used to determine the reactive species. As a result, carbon-centered radicals and free chlorine reactive species (Cl₂ and HClO) were devoted to BPA degradation in the PAA/Cl⁻ system. The carbon-centered radicals CH₃C(=O)OO^•, CH₃C(=O)O^•, CH₃OO^•, and ^•CH₃ greatly accelerated BPA degradation with their corresponding kinetics of k_{CH3C(=O)OO•, BPA} = 2 × 10⁸ M⁻¹ s⁻¹, k_{CH3C(=O)O•, BPA} = 2 × 10⁷ M⁻¹ s⁻¹, k_{•CH3, BPA} = 2 × 10⁶ M⁻¹ s⁻¹ and k_{CH3OO•, BPA} = 2 × 10⁴ M⁻¹ s⁻¹. Dissolved Cl₂(l) species was also important for BPA degradation with k_{Cl2, BPA} of 2 × 10⁷ M⁻¹ s⁻¹, much higher than HClO/ClO⁻ of k_{HClO, BPA} = 1.2 × 10¹ M⁻¹ s⁻¹ and k_ClO−_{, BPA} = 9 × 10⁻³ M⁻¹ s⁻¹. While free chlorine tends to transform BPA to estrogenic chlorinated organic products, the primary degradation of BPA by carbon-centered radicals results in chlorine-free products, reducing the production of disinfection byproducts during the treatment of saline wastewater. This study improves the knowledge of reaction kinetics and mechanism and reactive species generation in the PAA/Cl^– system.