Catalytic Peroxymonosulfate activation via In-Situ ketone Derivatives: Unveiling dual kinetics in electrochemical degradation

Abstract

This study reports for the first time the dual kinetics phenomenon triggered by the in situ generated ketone derivatives in the cathode chamber and reveals the mode of catalytic persulfate activation through electron exchange by the conversion of ketone functional groups to ketone derivatives. The experimental results show that the reaction rate constant in the rapid degradation stage in the cathode chamber (42.62 × 10^-2 min⁻¹) is significantly higher than that in the induction stage (2.11 × 10^-2 min⁻¹), achieving 98.96 % removal within 25 min. The intermediate validation experiments indicate that the in-situ generation of ketone-containing intermediates in the cathode chamber increases the steady-state concentration of reactive species (from 1.71 × 10^-10 to 1.08 × 10^-9 ML^-1), which is the main reason for the increased reaction rate. The ketone capture experiments and density functional theory (DFT) calculations show that the intermediates with ketone functional groups exchange electrons with persulfate ions under alkaline conditions and in the presence of an electric field, generating additional sulfate radicals and singlet oxygen. In the cathode chamber, the electrochemical activation of Peroxymonosulfate (PMS) by ketones on intermediate products is expected to become an inherent catalytic technology for the selective oxidation of pollutants occurring in aquatic environments.