| TiO2诱导下左旋氧氟沙星的可见光降解及其机制 |
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| 引用本文： | 郭宏生,刘亚楠,乔琪,魏红,董呈幸,薛洁,李克斌. TiO2诱导下左旋氧氟沙星的可见光降解及其机制[J]. 环境科学, 2015, 36(5): 1700-1706 |
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| 作者姓名： | 郭宏生 刘亚楠 乔琪 魏红 董呈幸 薛洁 李克斌 |
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| 作者单位： | 西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127;西安市自来水有限公司第二水厂, 西安 710043;西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127;西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127;西安理工大学西北水资源与环境生态教育部重点实验室, 西安 710048;西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127;西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127;西北大学化学与材料科学学院, 合成与天然功能分子化学教育部重点实验室, 西安 710127 |
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| 基金项目： | 陕西省自然科学基金项目(2013JM2011); 陕西省教育厅科学研究计划项目(12JK0643) |
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| 摘 要： | 左旋氧氟沙星是一种新型污染物.单一的左旋氧氟沙星(LFV)和Ti O2无可见光响应,但二者共存下左旋氧氟沙星能发生显著的可见光降解.为此研究Ti O2用量、溶液p H以及左旋氧氟沙星浓度对Ti O2/Vis(可见光)降解左旋氧氟沙星的影响及机制.结果表明,左旋氧氟沙星能吸附在Ti O2表面,吸附服从准二级吸附动力学和Langmuir吸附等温线.吸附左旋氧氟沙星的Ti O2漫反射UV-Vis光谱进一步表明二者形成表面复合物.左旋氧氟沙星的Ti O2/Vis降解动力学符合LangmuirHinshelwood方程.合适的Ti O2浓度和中性p H有利于光解过程的进行.自由抑制实验、N2保护下左旋氧氟沙星的Ti O2/Vis降解实验揭示·O-2是该过程中的主要活性物种.同时,无氧左旋氧氟沙星-Ti O2悬浮液光照不同时间的UV-Vis光谱证明体系中存在电子向Ti O2导带的注入.依据实验结果提出吸附在Ti O2表面的左旋氧氟沙星与Ti O2形成表面复合物,在可见光照下发生电子迁移,从而引发左旋氧氟沙星降解.本研究表明利用污染与Ti O2形成表面复合物诱导其可见光降解可用来去除水中某些有机污染物.
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| 关 键 词： | 降解 光化学 动力学 左旋氧氟沙星 TiO2 |
| 收稿时间： | 2014-10-11 |
| 修稿时间： | 2014-11-28 |
TiO2-Induced Photodegradation of Levofloxacin by Visible Light and Its Mechanism |
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| GUO Hong-sheng,LIU Ya-nan,QIAO Qi,WEI Hong,DONG Cheng-xing,XUE Jie and LI Ke-bin. TiO2-Induced Photodegradation of Levofloxacin by Visible Light and Its Mechanism[J]. Chinese Journal of Environmental Science, 2015, 36(5): 1700-1706 |
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| Authors: | GUO Hong-sheng LIU Ya-nan QIAO Qi WEI Hong DONG Cheng-xing XUE Jie LI Ke-bin |
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| Affiliation: | Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China;The Second Water Plant, Xi'an Tap Water Co., Ltd., Xi'an 710043, China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China;Key Laboratory of Northwest Water Resources Environment and Ecology, Ministry of Education, Xi'an University of Technology, Xi'an 710048, China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Material Science, Northwest University, Xi'an 710127, China |
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| Abstract: | Levofloxacin is an emerging pollutant. Single levofloxacin and TiO2 have no visible-light activity. However, photodegradation of levofloxacin dramatically enhanced in the presence of TiO2 under visible light irradiation. Considering this finding, the photodegradation of levofloxacin over TiO2 was investigated under visible light irradiation. Effects of TiO2 dosage, levofloxacin concentration, and solution pH on levofloxacin photodegradation were examined by monitoring its concentration decay with time. The results showed that levofloxacin photodegradation fitted the Langmuir-Hinshelwood kinetic model. Solution pH, TiO2 dose, and levofloxacin concentration had significant effects on the photodegradation rates. In addition, batch adsorption experiments revealed that adsorption of levofloxacin on TiO2 conformed to the pseudo-second-order kinetics and the Langmuir isotherm. DRS spectrum of levofloxacin-adsorbed TiO2 suggested that a surface complex was formed between levofloxacin and TiO2. Addition of radical scavengers and N2-degassing affecting levofloxacin photodegradation indicated that the superoxide ion radical was mainly active species. UV-Vis spectra of a deaerated TiO2 and levofloxacin suspensions further confirmed that the electron injection into TiO2 conduction band took place under visible light irradiation. Based on these results, a charge-transfer mechanism initiated by photoexcitation of TiO2/levofloxacin surface complex was proposed for levofloxacin photocatalytic degradation over TiO2 under visible light. This study indicates that the charge-transfer-complex-mediated photocatalytic technique has promising applications in the removal of colorless organic pollutants. |
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| Keywords: | degradation photochemistry kinetics levofloxacin titanium dioxide |
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