Sustained molecular oxygen activation by iron doped silicon carbide (Fe/SiC) was investigated under microwave (MW) irradiation. The catalytic performance of Fe/SiC for norfloxacin (NOR) degradation was also studied. Rapid mineralization in neutral solution was observed with a pseudo-first-order rate constant of 0.2239 min⁻¹ under 540 W of MW irradiation for 20 min. Increasing Fe/SiC rod and MW power significantly enhanced the degradation and mineralization rate with higher yield of reactive oxygen species (ROS). Fe shell corrosion and subsequent Fe^0/II oxidation by molecular oxygen with MW activation was the key factor for NOR degradation through two-electron-transfer by Fe⁰ under acidic conditions and single-electron-transfer by Fe^II under neutral-alkaline solution. Removal rate of NOR was significantly affected by solution pH, showing higher degradation rates at both acidic and alkaline conditions. The highest removal efficiencies and rates at alkaline pH values were ascribed to the contribution of bound Fe^II species on the Fe shell surface due to the hydroxylation of Fe/SiC. ·OH was the main oxidizing specie for NOR degradation, confirmed by density functional theory (DFT) calculations and radical scavenger tests. DFT calculations were conducted on the reaction/activation energies of the transition/final states of NOR/degradation products, combined with intermediate identification with high performance liquid chromatography coupled with a triple-quadruple mass spectrometer (HPLC-MS/MS), the piperazinyl ring was the most reactive site for ·OH attack, followed by further ring-opening and stepwise oxidation. In this study, Fe/SiC were proved to be an excellent catalyst for the treatment of fluoroquinolone antibiotics with MW activation.

中文翻译：

---

固体铁掺杂碳化硅在微波辐射下持续的分子氧活化：诺氟沙星降解的机理及其应用

在微波（MW）辐照下研究了铁掺杂的碳化硅（Fe / SiC）对分子氧的持续活化作用。还研究了Fe / SiC对诺氟沙星（NOR）降解的催化性能。在540 W的MW照射20分钟下，在中性溶液中观察到快速矿化，伪一级速率常数为0.2239 min ^-1。Fe / SiC棒和MW功率的增加显着提高了降解和矿化速率，并提高了活性氧（ROS）的产率。Fe壳的腐蚀以及随后被分子氧激活并被MW活化的Fe ^{0 / II}氧化是在酸性条件下通过Fe ^0的两电子转移和Fe ^II的单电子转移进行NOR降解的关键因素在中性碱性溶液中。溶液的pH显着影响了NOR的去除率，在酸性和碱性条件下均显示出更高的降解率。在碱性pH值下，最高去除效率和去除率归因于结合的Fe ^II的贡献由于Fe / SiC的羟基化作用，Fe壳表面的金属种类增加。·OH是NOR降解的主要氧化物质，已通过密度泛函理论（DFT）计算和自由基清除剂测试得到证实。对NOR /降解产物的过渡/最终状态的反应/活化能进行DFT计算，结合高效液相色谱与三重四极杆质谱仪（HPLC-MS / MS）的中间鉴定，哌嗪基环是·OH攻击的最活泼的位点，然后进一步开环和逐步氧化。在这项研究中，Fe / SiC被证明是具有MW活化作用的氟喹诺酮类抗生素治疗的优良催化剂。