Degradation of hexavalent chromium and methyl orange by the synergistic system of graphitic carbon nitride and electron beam irradiation
Degradation of hexavalent chromium and methyl orange by the synergistic system of graphitic carbon nitride and electron beam irradiation
复制标题
石墨氮化碳与电子束辐照协同体系降解六价铬和甲基橙
DOI：
10.1016/j.chemosphere.2021.132228
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发表时间：
2021-09-13
期刊：
影响因子：
8.8
通讯作者：
Wu, Zhengyan
中科院分区：
文献类型：
--
作者：
Ma, Xijun;Zhou, Yiming;Wu, Zhengyan
六价铬（Cr（VI））和甲基橙子（MO）具有很高的毒性，难以处理。电子束辐照（EB）可产生.OH、H.、.O2-、水合电子（eaq-）等活性物质，对污染物具有较强的氧化还原能力。然而，EB的渗透能力是有限的（水的渗透深度为10 cm）。因此，本项目采用石墨氮化碳（CN）的光催化方法作为EB的协同方法降解Cr（VI）和MO。结果表明，在液面高度为5 cm时，100 mg L-1Cr（VI）和50 mg L-1 MO的最大处理效率分别为95.0%和99.1%，远高于单一光催化法（39.5%，23.4%）和EB（79.6%，92.1%），且在酸性条件下协同处理效率较高。当液深增加到30 cm时，协同体系对Cr（VI）和MO的降解效率分别下降了14.7%和15.2%，低于单独EB处理的47.2%和45.7%。此外，在协同系统之前和之后，CN的形貌、光吸收性能和光生电子-空穴对的分离的性能被评估。机理分析表明，在Cr（VI）还原过程中，EB、e（aq）（-）、光生电子的电子效应和热效应起着关键作用，而在MO降解过程中，EB、中心点O-2（-）、光生空穴的电子效应和热效应起着关键作用。本研究为光催化剂与EB协同体系处理污染物提供了新的契机。
Hexavalent chromium (Cr(VI)) and methyl orange (MO) are highly toxic and difficult to treat. Electron beam irradiation (EB) can produce .OH, H., .O2-, hydrated electron (eaq-) and other active substances, which have strong redox ability to pollutants. However, the penetration capacity of EB is limited (the penetration depth of water is 10 cm). Therefore, the photocatalytic method of graphitic carbon nitride (CN) was used as the synergistic method of EB in this project to degrade Cr(VI) and MO. The results showed that the maximum treatment efficiency of 100 mg L-1 Cr(VI) and 50 mg L-1 MO with liquid surface height of 5 cm was 95.0% and 99.1%, respectively, which was much higher than that of single photocatalytic method (39.5%, 23.4%) and EB (79.6%, 92.1%), and the efficiency of synergistic treatment was higher under acidic condition. When the liquid depth increased to 30 cm, the efficiency of synergistic system decreased by 14.7% and 15.2% for the degradation of Cr (VI) and MO, respectively, less than the single EB treatment (47.2%, 45.7%). Additionally, the performance of the morphology, the light absorption performance, and the separation of photogenerated electron-hole pairs of the CN were evaluated before and after the synergistic system. Lastly, the mechanism illustrates that the electron and thermal effects of EB, e(aq)(-), photogenerated electrons played key roles for the Cr(VI) reduction, and the electron and thermal effects of EB, center dot O-2(-), photogenerated holes played key roles for the MO degradation. This study provides a new opportunity for the synergistic system of photocatalyst and EB in the treatment of pollutants.