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首页> 外文期刊>Environmental Science & Technology >Effects of TiO_2 Surface Modifications on Photocatalytic Oxidation of Arsenite: The Role of Superoxides
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Effects of TiO_2 Surface Modifications on Photocatalytic Oxidation of Arsenite: The Role of Superoxides

机译：TiO_2表面改性对亚砷酸盐光催化氧化的影响：超氧化物的作用

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摘要

Using TiO_2 photocatalyst, arsenite [As(Ⅲ)] can be rapidly oxidized to arsenate [As(Ⅴ)], which is less toxic and less mobile in the aquatic environment. Superoxides have been recently proposed as a main photocatalytic oxidant of As(Ⅲ) whereas OH radicals are dominant oxidants in most TiO_2 photocatalytic oxidation (PCO) reactions. This study confirms that superoxides are mainly responsible for the As(Ⅲ) PCO by investigating PCO kinetics in pure and modified TiO_2 systems. The rate of As(Ⅲ) oxidation drastically increased on Pt-TiO_2, which could be ascribed to the enhanced superoxide generation through an efficient interfacial electron transfer from the conduction band (CB) to O_2. Since the addition of fert-butyl alcohol (OH radical scavenger) had little effect on the PCO rate in both naked and Pt-TiO_2 suspensions, OH radicals do not seem to be involved. The addition of polyoxometalates (POMs) as an electron shuttle between TiO_2.CB and O_2 highly promoted the PCO rate whereas the POM alone was not effective at all in oxidizing As(Ⅲ). Fluorinated TiO_2 that had a markedly reduced adsorptive capacity for As(Ⅲ) did not show a reduced PCO rate, which indicates that the direct hole transfer path is not important. The arsenite oxidation proceeded under visible light with a similar rate to the case of Pt-TiO_2/UV when dye-sensitized Pt-TiO_2 was used. Since only superoxides can be generated as a photooxidant in this visible light system, their role as a main oxidant of As(Ⅲ) is confirmed. In addition, the PCO rate was significantly reduced in the presence of superoxide dismutase.
机译：使用TiO_2光催化剂，亚砷酸盐[As（Ⅲ）]可以被快速氧化成砷酸盐[As（Ⅴ）]，在水生环境中毒性较小，流动性较低。最近有人提出将超氧化物作为As（Ⅲ）的主要光催化氧化剂，而在大多数TiO_2光催化氧化（PCO）反应中，OH自由基是主要的氧化剂。通过研究纯和改性TiO_2系统中的PCO动力学，该研究证实了超氧化物是As（Ⅲ）PCO的主要起因。 Pt-TiO_2上As（Ⅲ）的氧化速率急剧增加，这可以归因于通过有效的界面电子从导带（CB）到O_2的有效转移提高了超氧化物的产生。由于添加叔丁基醇（OH自由基清除剂）对裸露和Pt-TiO_2悬浮液的PCO速率影响很小，因此似乎不涉及OH自由基。在TiO_2.CB和O_2之间以电子穿梭形式添加多金属氧酸盐（POMs）可以极大地提高PCO速率，而单独的POM对氧化As（Ⅲ）完全无效。对As（Ⅲ）具有明显降低的吸附能力的氟化TiO_2并未显示出降低的PCO速率，这表明直接的空穴传输路径并不重要。当使用染料敏化的Pt-TiO_2时，砷在可见光下的氧化速率与Pt-TiO_2 / UV相似。由于在该可见光系统中只能生成超氧化物作为光氧化剂，因此可以确认它们作为As（Ⅲ）的主要氧化剂的作用。另外，在超氧化物歧化酶的存在下，PCO速率显着降低。

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  • 来源
    《Environmental Science & Technology》 |2004年第10期|p.2928-2933|共6页
  • 作者

    JUNGHO RYU; WONYONG CHOI;

  • 作者单位

    School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境化学;
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