Degradation of p-Nitrophenol (PNP) via photocatalytic ozonation using perylene diimide polymer

p-Nitrophenol (PNP), a widely used chemical intermediate, exhibits stubborn resistance to conventional oxidation treatments due to its high toxicity, electron-deficient nature, and the high stability of its aromatic ring. To address the bottlenecks of low mineralization efficiency of PNP by traditional ozonation and the limited spectral utilization of conventional PCO systems. Herein, we constructed a photocatalytic–ozone synergistic system based on perylene diimide-based organic polymers (Urea-PDI/O 3 /vis). Owing to the broad spectral response of the polymers, the light-responsive range of this coupled system can be extended to the near-infrared region up to 700 nm. The degradation rate of PNP in this system is 25 times higher than that in the photocatalytic system alone and 2.42 times greater than that in the ozone system alone. More importantly, the mineralization efficiency of PNP is significantly enhanced in the Urea-PDI/O 3 /vis, reaching a value three times higher than that of the traditional ozone system. Mechanism investigation reveals that the denitrification efficiency for PNP is comparable between the ozonation and photocatalytic–ozone systems. However, the photocatalytic–ozone process demonstrates a marked superiority in the subsequent ring cleavage and mineralization via decarboxylation of small-molecular organic acids. In contrast to the direct ozonation mechanism dominated by electrophilic and dipolar addition reactions, the Urea-PDI/O 3 /vis efficiently utilizes photogenerated electrons to convert ozone into hydroxyl radicals in large quantities, which enables highly efficient mineralization of PNP. This study will provide new insights into the removal of PNP in water.