稀土改性铋基光催化剂制备及其对高浓度染料的光催化降解性能研究

发布时间：2017-12-30 17:51

  本文关键词：稀土改性铋基光催化剂制备及其对高浓度染料的光催化降解性能研究　出处：《江西理工大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 稀土 铋基 Bi2O3 Bi2MoO6 BiOCl 光催化 高浓度染料

【摘要】：半导体光催化氧化技术能利用光能完全矿化有机污染物,在水处理领域中具有广泛的应用前景。铋基半导体化合物具有价廉、环保的特点,已经成为新型光催化剂开发领域的研究热点。稀土因其独特的电子结构是一种重要的改性剂。稀土改性铋基光催化剂目前鲜有报道,尤其缺少系统性研究稀土对铋基光催化剂改性。目前也缺少针对光催化降解高浓度污染物的研究。本文以降解高浓度污染物为目标,首先系统研究了掺杂镧系元素对Bi2O3光催化性能的影响。在此基础上,通过稀土离子掺杂与稀土氧化物复合进一步研究稀土对铋基光催化剂结构与性能的影响。主要研究内容如下:1.采用水热-热处理法制备稀土掺杂Bi2O3光催化剂。考察了不同稀土元素及热处理温度对光催化性能的影响。结果表明:掺入稀土有效抑制Bi2O3由β-Bi2O3向α-Bi2O3的相转变,有助于β-Bi2O3相稳定。稀土掺杂使样品不同程度的红移并将光吸收范围拓展到550 nm以上。可见光照射下高浓度酸性橙II的光催化降解实验表明,稀土元素掺杂Bi2O3具有良好的可见光催化性能,其中轻稀土以Nd、Pr及重稀土Gd、Er掺杂的催化剂可见光催化效率较佳。2.采用水热-焙烧法制备Eu3+掺杂Bi2MoO6光催化剂。结果表明,所有样品均为正交晶系的γ-Bi2MoO6,Eu3+掺杂进入Bi2MoO6晶格代替部分Bi3+,Bi2MoO6晶格畸变程度增强,结晶度下降晶粒细化。Eu3+能够调节Bi2MoO6能带结构,降低Bi2MoO6禁带宽度。由于Eu3+和Eu2+之间可以相互转换,提高了光生电子和空穴的分离,光催化活性得到显著提高。3.采用了沉淀法制备BiOCl前驱体,再利用研磨焙烧法合成La2O3复合光催化剂。该系列催化剂均具有较好的结晶性能,具有片状形貌。La可取代BiOCl晶格中部分Bi。讨论了不同复合含量和焙烧温度对合成样品的光催化性能的影响,并且当La的复合量为1 wt%,200℃焙烧3 h,La2O3/BiOCl样品的光催化效率最佳。La2O3/BiOCl在高浓度染料降解中表现出更好的光催化性能,这主要是由于复合La2O3后,La3+提供有利于的氧化-还原势阱成为光生电子缺陷,阻止了电子-空穴对的复合。综合表明,稀土能够调控铋基化合物的晶体结构、光吸收性能并抑制光生电子-空穴对的复合,从而可以大幅度提高铋基化合物降解高浓度有机污染物的光催化性能。
[Abstract]:Semiconductor photocatalytic oxidation technology can use light energy to completely mineralize organic pollutants, and has a wide application prospect in the field of water treatment. Bismuth based semiconductor compounds have the characteristics of low price and environmental protection. Rare earth is an important modifier because of its unique electronic structure. Rare earth modified bismuth based photocatalyst is rarely reported at present. In particular, there is a lack of systematic study on the modification of bismuth-based photocatalysts by rare earths. At present, there is no research on photocatalytic degradation of high-concentration pollutants. The aim of this paper is to degrade high-concentration pollutants. The effect of doped lanthanide on the photocatalytic properties of Bi2O3 was studied. The effects of rare earth on the structure and properties of bismuth based photocatalysts were further studied by doping rare earth ions with rare earth oxides. The main contents are as follows:. 1. Rare earth doped Bi2O3 photocatalysts were prepared by hydrothermal heat treatment. The effects of rare earth elements and heat treatment temperature on photocatalytic properties were investigated. The phase transition of Bi2O3 from 尾 -Bi _ 2O _ 3 to 伪 -Bi _ 2O _ 3 was effectively inhibited by the addition of rare earth. It is helpful for the stability of 尾 -Bi _ 2O _ 3 phase. Rare earth doping makes the samples red-shift to varying degrees and expands the absorption range to 550. The photocatalytic degradation of acid orange II with high concentration under visible light irradiation was studied. Rare earth element doped Bi2O3 has good visible light catalytic performance, among which the light rare earth is NdPr and the heavy rare earth Gd. The visible light catalytic efficiency of er doped catalyst was better. 2. Eu3 doped Bi2MoO6 photocatalyst was prepared by hydrothermal calcination method. All the samples were doped with 纬 -Bi2MoO6EU _ 3 into the Bi2MoO6 lattice instead of part of the Bi3 _ 2MoO _ 6 crystal lattice, and the distortion degree of the crystal lattice was enhanced. The decrease of crystallinity. EU3 can adjust the band structure of Bi2MoO6 and decrease the band gap of Bi2MoO6. Because of the interconversion between Eu3 and Eu2. The photocatalytic activity was improved significantly. 3. The BiOCl precursor was prepared by precipitation method. The La2O3 composite photocatalyst was synthesized by grinding roasting method. The series of catalysts have good crystallization performance. The effects of different composition content and calcination temperature on the photocatalytic properties of the synthesized samples were discussed, and the composition of La was 1 wt%. The photocatalytic efficiency of La _ 2O _ 3 / BiOCl sample calcined at 200 鈩，

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