Unveiling the Key Role of Surface Oxidation through Quantifying Reaction Kinetics in Heterogeneous Catalysis for Water Treatment

Quantifying surface-specific kinetics of organic oxidation in heterogeneous catalytic systems remains a critical challenge due to the interplay of adsorption and complex reaction mechanisms. In this study, we introduce a novel kinetic framework that distinguishes surface reaction kinetics (<i>k</i>_c) from conventional solution-phase kinetics (<i>k</i>_b), using nitrogen-doped porous carbon (NPC) as a model catalyst with high adsorption capacity and exceptional efficacy in peroxymonosulfate (PMS) activation. By directly analyzing the selective oxidation of fully adsorbed <i>para</i>-substituted phenolic compounds (<i>p</i>-PCs), we precisely quantified <i>k</i>_c and established robust QSAR models with remarkable linear correlations (<i>R</i>² = 0.862-0.912) to molecular descriptors such as Hammett constant (σ), highest occupied molecular orbital energy (<i>E</i>_HOMO), and ionization potential (IP). In contrast, <i>k</i>_b-based models showed weaker correlations (<i>R</i>² = 0.363-0.551), reflecting interference from adsorption-desorption dynamics. This distinction underscores the limitations of solution-phase kinetics in systems with strong adsorption properties and highlights the enhanced mechanistic understanding and predictive power of surface-specific models. Further analysis revealed surface-selective oxidation via an electron transfer pathway, predominantly governed by the electronic properties of <i>p</i>-PCs rather than their adsorption affinity. These findings provide a valuable approach to accurately capture surface reactivity and predicting pollutant behavior in heterogeneous sorption-oxidation systems.