Simultaneous photoreduction of Uranium(VI) and photooxidation of Arsenic (III) in aqueous solution over g-C3N4/TiO2 heterostructured catalysts under simulated sunlight irradiation
Simultaneous photoreduction of Uranium(VI) and photooxidation of Arsenic (III) in aqueous solution over g-C3N4/TiO2 heterostructured catalysts under simulated sunlight irradiation
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DOI：
10.1016/j.apcatb.2018.01.062
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发表时间：
2018-07-15
影响因子：
22.1
通讯作者：
Wang, Xiang-Ke
中科院分区：
文献类型：
--
作者：
Jiang, Xun-Heng;Xing, Qiu-Ju;Wang, Xiang-Ke
本论文合成了g-C3 N4/TiO 2复合催化剂，并通过XRD、SEM、TEM、拉曼光谱、紫外-可见漫反射光谱、PL、Mott-Schottky和XPS等手段对催化剂进行了表征。首次在g-C3 N4/TiO 2催化剂上实现了铀（VI）的光还原和砷（III）的光氧化。实验结果表明，随着As（III）浓度的增加，U（VI）的去除率降低，而As（III）光氧化为As（V）的速率则随着As（III）浓度的增加而增加。XPS分析证实了U（VI）光还原为U（IV）和As（III）光氧化为As（V）的过程。自由基捕获和定量测试结果表明，空穴、羟基自由基和超氧阴离子自由基是As（III）光氧化的主要活性物种，而U（VI）被光生电子还原为U（IV）。此外，还提出了一种可能的机制来解释g-C3 N4/TiO 2光催化性能的提高以及U（VI）光还原和As（III）光氧化之间的竞争关系。本工作开发了一种具有潜在应用前景的异质结构催化剂，用于同时去除U（VI）和As（III），并首次明确了As（III）的光氧化对U（VI）光还原的影响。
In the present work, the hererostructured catalysts of g-C3N4/TiO2 were synthesized and well characterized by XRD, SEM, TEM, Raman, UV-vis diffuse reflectance spectra, PL, Mott-Schottky, and XPS. Simultaneous photo reduction of Uranium(VI) and photooxidation of Arsenic(III) was firstly achieved over the g-C3N4/TiO2 catalysts. And the experimental results show that the removal rate of U(VI) decreases with the increase of As(III) concentration, whereas the photooxidation rate of As(III) to As(V) increases with the increase of As(III) concentration. Noteworthily, the photoreduction of U(VI) to U(IV) and photooxidation of As(III) to As(V) was confirmed by XPS analysis in time-scale. The experimental results of free radical capture and quantitative test indicate that holes, hydroxyl radical and superoxide radical are the major active species for photooxidation of As (III), while U(VI) was reduced to U(IV) by the photogenerated electrons. Furthermore, a possible mechanism was proposed to well explain the improved photocatalytic performance of the g-C3N4/TiO2 and the competitive relationship between photoreduction of U(VI) and photooxidation of As(III). The present work develops a heterostructured catalyst for potential application to the simultaneous removal of U(VI) and As(III), and makes clear the effect of photooxidation of As(III) on photoreduction of U(VI) for the first time.