Catalytic ozonation of dissolved acetaminophen with iron-doped graphitic carbon nitride in plasma-liquid system

Iron-based materials have been widely employed for initiating Fenton-like reactions and catalytic ozonation in plasma-liquid interactions. However, there is still a lack of consensus about the reaction’s selectivity and catalytic mechanism. Herein, elemental iron-doped graphitic carbon nitride (Fe/g-C3N4) is prepared and utilized to enhance the plasma oxidation of acetaminophen via selective catalysis of ozone. Unlike traditional heterogeneous catalytic ozonation, the superoxide anion is identified as the primary derivative species by electron paramagnetic resonance experiments and a kinetic analysis of quenching experiments. The singlet oxygen as a disproportionation product of superoxide anion is also involved in the degradation of acetaminophen, with the generation of additional hydrogen peroxide. Additionally, degradation pathways of acetaminophen involving multiple reactive species and optical emission are proposed. These findings provide novel insight into the mechanism of heterogeneous catalytic ozonation with Fe/g-C3N4 in plasma-liquid interactions for organic contaminant removal from water.