| 金属有机框架MIL-53(Fe)可见光催化还原水中U(Ⅵ) |
| 摘要点击 3113 全文点击 1005 投稿时间：2018-09-04 修订日期：2018-10-08 |
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| 中文关键词 金属有机框架 U(Ⅵ) 光催化还原 MIL-53(Fe) 空穴捕获剂 |
| 英文关键词 metal organic framework U (Ⅵ) photocatalytic reduction MIL-53(Fe) hole trapping agent |
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| 中文摘要 |
| U（Ⅵ）是放射性废液中铀的主要存在形式.将可溶的U（Ⅵ）还原为难溶的U（Ⅳ）是治理铀污染的有效方法.以溶剂热法合成了铁基金属有机框架材料MIL-53（Fe）.在表征了材料的结构及光响应特性基础上，开展了MIL-53（Fe）在可见光下催化还原水中U（Ⅵ）的研究.探究了空穴捕获剂种类、空穴捕获剂浓度、反应体系pH及催化剂用量等对U（Ⅵ）光催化还原的影响.结果表明，空穴捕获剂甲酸的加入可有效提高光催化反应的电荷分离效率.当甲酸浓度为1 mmol·L-1时，400 mg·L-1的MIL-53（Fe）在可见光下，2 h内对初始浓度为50 mg·L-1的U（Ⅵ）去除率达到80%；光电子能谱检测结果显示反应中有U（Ⅳ）生成，推测其主要反应机制是甲酸与MIL-53（Fe）的光生空穴反应产生强还原性的·COO-，将U（Ⅵ）还原为U（Ⅳ），从而实现对水中U（Ⅵ）的光催化去除. |
| 英文摘要 |
| Uranium typically occurs in the hexavalent form U(Ⅵ) as the mobile, aqueous uranyl ion in radioactive wastewater. The reduction of soluble U(Ⅵ) to insoluble U(Ⅳ) oxide is an effective approach to eliminate uranium pollution. Herein, the metal organic framework material MIL-53(Fe) was successfully synthesized by a solvothermal method, and its application as photocatalyst in the reduction of U(Ⅵ) under visible light was studied in detail using various types and concentrations of hole trapping agents, solution pH values, and catalyst dosages. The results show that the use of formic acid as the hole trapping agent greatly accelerates the catalytic reaction rate by improving the charge separation efficiency. When 1 mmol·L-1 formic acid was used and the initial concentration of U(Ⅵ) was 50 mg·L-1, MIL-53(Fe) achieved a high reduction rate of 80% after 2 hours of visible light exposure. Photoelectron spectroscopy (XPS) clearly suggested that U(Ⅳ) was generated during the reaction process. A possible mechanism is that formic acid reacted with the photogenerated hole, resulting in the formation of·COO-, which can reduce U(Ⅵ) to U(Ⅳ). Accordingly, the elimination of the uranium pollution from wastewater was achieved. |
