Sustained molecular oxygen activation by solid iron doped silicon carbide under microwave irradiation: Mechanism and application to norfloxacin degradation
Sustained molecular oxygen activation by solid iron doped silicon carbide under microwave irradiation: Mechanism and application to norfloxacin degradation
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微波辐射下固体铁掺杂碳化硅的持续分子氧活化：诺氟沙星降解机理及其应用
DOI：
10.1016/j.watres.2017.09.001
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发表时间：
2017
期刊：
影响因子：
12.8
通讯作者：
Crittenden John C
中科院分区：
文献类型：
--
作者：
Li Hongbo;Chen Jing;Hou Huijie;Pan Hong;Ma Xiaoxue;Yang Jiakuan;Wang Linling;Crittenden John C
研究了微波辐射下Fe掺杂SiC（Fe/SiC）对分子氧的持续活化作用。研究了Fe/SiC对诺氟沙星（NOR）的催化降解性能。在中性溶液中，在540 W的MW照射20 min下观察到快速矿化，其伪一级速率常数为0.2239 min-1。增加Fe/SiC棒和微波功率显著提高了降解和矿化速率，活性氧（ROS）产率更高。铁壳的腐蚀和分子氧对Fe 0/II的氧化是NOR降解的关键因素，在酸性条件下Fe 0发生双电子转移，而在中性-碱性条件下Fe II发生单电子转移。溶液pH值对NOR的去除率有显著影响，酸性和碱性条件下的去除率均较高。在碱性pH值下的最高去除效率和速率归因于Fe/SiC的羟基化导致的Fe壳表面上的结合FeII物种的贡献。密度泛函理论（DFT）计算和自由基清除剂实验证实了·OH是NOR降解的主要氧化物种。采用密度泛函理论计算了NOR/降解产物过渡态/终态的反应活化能，结合高效液相色谱-三重四极杆质谱（HPLC-MS/MS）对中间体的鉴定，发现哌嗪环是·OH攻击最活跃的位点，其次是进一步开环和逐步氧化.在本研究中，Fe/SiC被证明是一个很好的催化剂，用于处理氟喹诺酮类抗生素与MW活化。
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−1under 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 Fe0/IIoxidation by molecular oxygen with MW activation was the key factor for NOR degradation through two-electron-transfer by Fe0under acidic conditions and single-electron-transfer by FeIIunder 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 FeIIspecies 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.