Ferryl-Involved Oxidation Coupling Processes over K x FeOCl Enzyme-Mimetic Catalysis: Mechanistic Insights and Kinetic Modeling

Enzyme-mimetic metal-based catalysts have received extensiveattentionfor the efficient catalytic applications. These catalysts can be adaptedto complex environmental circumstances, thus becoming one of the effectiveways to deal with refractory pollutants. In previous research, theK(+)-intercalated FeOCl (K x FeOCl)catalyst can produce Fe(IV)UO intermediate species throughheterocleavage of H2O2 in a similar way as naturalperoxidases. In this study, the detailed kinetics and surface reactionmechanisms of K x FeOCl were comprehensivelyinvestigated using 2-methoxyphenol (2-MeOP) as the model contaminantand at pH 7. 2-MeOP molecules are oxidized to organic radicals, whichfurther oxidize 2-MeOP for direct radical-radical coupling.Based on the kinetics, the Langmuir-Hinshelwood model was usedto describe the oxidative coupling of 2-MeOP on the K x FeOCl/H2O2 system. The competitiveadsorption of H2O2 and downstream catalase activityof H2O2 decomposition were also proposed. Thesubstrate oxidation rate of high-valent iron species reached 9.25x 10(5) mM(-1) min(-1). These results clarified the intrinsic kinetic principle and interfacialreaction mechanism of 2-MeOP oxidative coupling catalyzed by K x FeOCl, offering valuable insights for optimizingreaction performance and scaling up the process. The K+ intercalated modifiedFeOCl material withperoxidase-like catalytic activity enables the oxidative couplingpolymerization of pollutants similar to the humification process andhas significant potential in pollutant treatment.