Electrochemical oxidation of ofloxacin using a TiO2-based SnO2-Sb/polytetrafluoroethylene resin-PbO2 electrode: Reaction kinetics and mass transfer impact
Electrochemical oxidation of ofloxacin using a TiO2-based SnO2-Sb/polytetrafluoroethylene resin-PbO2 electrode: Reaction kinetics and mass transfer impact
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DOI：
10.1016/j.apcatb.2016.10.057
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发表时间：
2017-04
影响因子：
22.1
通讯作者：
Ruzhen Xie;Xiaoyang Meng;Peizhe Sun;J. Niu;Wenju Jiang;L. Bottomley;Duo Li;Yongsheng Chen;J. Crittenden
中科院分区：
文献类型：
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作者：
Ruzhen Xie;Xiaoyang Meng;Peizhe Sun;J. Niu;Wenju Jiang;L. Bottomley;Duo Li;Yongsheng Chen;J. Crittenden
电化学氧化已被提出用于破坏有机污染物;然而，该过程受到低氧化效率和高能量成本的阻碍。因此，我们研制了一种基于TiO 2纳米管的SnO 2-Sb/聚四氟乙烯树脂（FR）-PbO 2电极。我们测试了电极对抗生素氧氟沙星的性能，并确定了氧氟沙星氧化的主要途径。我们发现在Ti材料上生长TiO_2纳米管提高了电流效率，氧化的单位电效率（EE/O，kWh/m3）降低了16.2%。我们的电极在电子流动之前需要一个大的过电位，这可以最大限度地减少氧气的释放，减少过氧化氢和臭氧的产生，并有利于羟基自由基（HOradical dot）的产生。氧化过程中的电子效率（EE）高达88.45%。换句话说，从电极流出的88.45%的电子引起氧化。考察了电流密度、初始浓度、pH值、电解质浓度等因素对电解质降解的影响。采用微分柱间歇式反应器（DCBR）对连续平推流反应器进行模拟，发现氧氟沙星的降解符合准一级动力学模型。我们还评估了传质对电化学性能的影响。通过测定传质系数和有效因子Ω（0 ~ 1），考察了流速和电极间距对氧化速率的影响。我们的实验和计算表明，在流速为0.033 m/s，电极间距为1 cm时，传质使氧化速率降低55%以上（Ω < 0.45）。与使用完全混合间歇式反应器进行的研究不同，DCBR可以模拟中试或全规模反应器中的流动条件;因此，在DCBR中观察到的伪一级速率常数可用于初步设计。
Electrochemical oxidation has been proposed for the destruction of organic contaminants; however, this process is hampered by low oxidation efficiency and high energy cost. Accordingly, we developed a TiO2-based SnO2-Sb/polytetrafluroethylene resin (FR)-PbO2electrode that was based on TiO2nanotubes. We tested the performance of the electrode on an antibiotic, ofloxacin, and identified the major pathway of ofloxacin oxidation. We found growing TiO2nanotubes on Ti material increased current efficiency, and the electrical efficiency per order (EE/O, kWh/m3) for oxidation was decreased by 16.2%. Our electrode requires a large overpotential before electrons flow, which minimizes oxygen evolution, reduces hydrogen peroxide and ozone generation, and favors hydroxyl radicals (HOradical dot) production. We found the electron efficiency (EE) during oxidation was as high as 88.45%. In other words, 88.45% of the electrons that flow out of the electrode cause oxidation. The effects of current density, initial concentration, pH value and electrolyte concentration were investigated. A differential column batch reactor (DCBR) was used to simulate the performance of continuous plug flow reactor and we found that the destruction of ofloxacin followed pseudo-first order model. We also evaluated the impact of mass transfer on electrochemical performance. The effects of fluid velocity and electrode spacing on oxidation rate were evaluated by determining the mass transfer coefficient and the effectiveness factor Ω (between 0 and 1). Our experiments and calculations indicated that the mass transfer reduced oxidation rate by more than 55% (Ω < 0.45) for an electrode spacing of 1 cm at a fluid velocity of 0.033 m/s. Unlike studies carried out using completely mixed batch reactor, the DCBR can simulate the flow conditions in pilot or full scale reactors; consequently, observed pseudo-first order rate constants in the DCBR can be used for preliminary design.