Dissolved organic matter composition influences catalytic oxidation behavior and product evolution in real water matrices.

Dissolved organic matter (DOM) strongly influences catalytic oxidation processes through complex matrix effects. Despite the widely recognized matrix effects of DOM, the relationships between DOM composition, product evolution, and transformation preference during catalytic oxidation remain poorly understood. In this study, nine water matrices with distinct DOM compositional characteristics were investigated to distinguish the effects of DOM composition from organic loading under TOC-normalized conditions during photocatalytic periodate activation. Results showed that DOM induced both promotive and inhibitory effects after eliminating concentration differences, highlighting the dominant influence of composition over abundance. Reactive species analysis indicated that DOM enhanced the contributions of hydroxyl radicals and high-valent iron species without altering the primary reactive oxygen species types. Product evolution analysis further showed that promotive samples with lower AreaTP3/AreaTP1 ratios were associated with enhanced deep oxidation, whereas inhibitory samples with higher ratios exhibited greater accumulation of local oxidation products. FT-ICR-MS analysis revealed a compositional shift of DOM toward compounds assigned to more aromatic and oxygen-enriched regions after reaction. Overall, the results demonstrate strong associations among DOM composition, catalyst surface behavior, and product evolution during catalytic oxidation in real water matrices, providing new insights into matrix effects in practical water treatment systems.