磁载核壳型TiO2复合光催化剂制备及其在处理染料废水中的应用研究
摘 要
本论文致力于高效 TiO2复合光催化材料的设计制备、表征及其光催化性能研
究，针对所合成复合光催化材料的特点，系统研究了不同组分掺杂、不同合成方
法对复合材料晶型结构与表面物理化学性质的影响，通过染料废水中有机污染物
的降解来考察该系列复合 TiO2纳米材料的光催化性能。
本文采用程序升温水热法与超声均相沉淀法相结合技术，制备了磁载核壳型
TiO2复合光催化剂如γ-Fe2O3/SiO2/TiO2纳米粒子、Fe3O4/TiO2等。通过 X射线粉
末衍射光谱（XRD）、扫描电子显微镜（SEM-EDS）、X-射线光电子能谱(XPS)测
试、透射电子显微镜(TEM 与HRTEM)、N2吸附、紫外可见固体漫反射（UV-Vis
DRS）测定等表征手段对合成材料的组成、结构、晶相及表面物理化学特性进行
了表征以及光催化性能人研究。
γ-Fe2O3/SiO2/TiO2复合光催化材料测试结果表明，γ-Fe2O3/SiO2/TiO2纳米核壳
结构复合光催化材料中的 TiO2以锐钛矿相存在，并且 γ-Fe2O3/SiO2/TiO2粒子的粒
径在 100nm左右，γ-Fe2O3/SiO2均匀地分散在 TiO2中，γ-Fe2O3/SiO2粒径大概 20nm
以及 SiO2层大概是 2nm~6nm，γ-Fe2O3/SiO2/TiO2光催化剂发生红移现象，在紫外
光范围内具有强烈的光吸收性能，且在可见光区 400nm~600nm 也有部分吸收，
从而使 TiO2的吸光范围变宽。γ-Fe2O3/SiO2/TiO2纳米核壳结构复合光催化剂在空
气中 450 ℃煅烧后，纳米 γ-Fe2O3/SiO2/TiO2磁性迅速降低，磁载核壳型
γ-Fe2O3/SiO2/TiO2复合光催化材料为双孔微孔-介孔结构，比表面积大。
另外，光催化反应中，研究 Fe:Ti 比、溶液初始 pH、催化剂投加量、溶液初
始浓度等不同因素对光催化降解效果的影响，γ-Fe2O3/SiO2/TiO2纳米核壳结构复
合光催化剂对罗丹明 B(RhB)染料光催化降解最好，在90min 内罗丹明 B(RhB)染
料转化率为 95%，其次是甲基橙（MO）90min 基本上转化率为 90%，与纯的 TiO2
相比，γ-Fe2O3/SiO2/TiO2复合光催化剂有较高的光催化活性，其降解效果的最佳
条件为：γ-Fe2O3/10%SiO2/45%TiO2复合光催化剂在酸性（pH=2）环境下降解效
果最佳，Fe 与Ti 比值为1:1 时，催化剂投加量的最佳值为 2.0g/L，催化剂循环使
用5次未发现活性有明显光催化活性下降。因此，γ-Fe2O3/SiO2/TiO2催化剂分离
回收简单，具有可观的应用前景。
Fe3O4/TiO2复合光催化材料测试结果表明，Fe3O4/TiO2纳米核壳结构复合光催
化材料中的 TiO2以锐钛矿相存在，并且 Fe3O4/TiO2粒子的粒径在 50nm~100nm 范
围内，Fe3O4均匀 地 分散 在 TiO2中 ， Fe3O4粒径 大概 20nm，Fe3O4/TiO2在
200nm~600nm 都有吸收，从而使 TiO2的吸光范围变宽，表明有 FeTiO3生成，。
Fe3O4/TiO2纳米核壳结构复合光催化剂在 N2保护中450℃煅烧后，纳米 Fe3O4/TiO2
磁性迅速降低，磁载核壳型 Fe3O4/TiO2复合光催化材料为双孔微孔-介孔结构，比
表面积大，有利于染料吸附在 Fe3O4/TiO2复合光催化材料表面，较快光催化反应。
另外，光催化反应中，在 120min 内罗丹明 B(RhB)染料转化率为 95%，研究
Fe：Ti 比对光催化降解效果的影响，36.7%Fe3O4/TiO2，即 Fe 与Ti 比值为1: 2 时，
Fe3O4/TiO2核壳结构复合光催化剂对染料废水罗丹明 B（RhB）（10mg/L 50mL）
降解，动力学方程的反应速率常数是 0.0332 min-1，反应速率常数最大。
通过分析 Fe3O4/TiO2光催化反应机理研究降解机理得出：（ ⅰ）在光催化过程
中，Fe3O4/TiO2复合光催化剂中首先是 TiO2吸收紫外光，产生光生电子/空穴对
(
he /
)，（ⅱ）FeTiO3和TiO2之间存在的协同效应，FeTiO3能够迅速捕获 TiO2
表面的导带（CB）电子（
e
）， 其结果也就是加快了导带电子的迁移速度，减少
了TiO2表面光生
he /
对之间的快速复合几率，FeTiO3的禁带能是 2.85eV，使得
Fe3O4/TiO2复合材料的光吸收带变宽，带隙能降低，电子更容易发生跃迁，产生
更多的光生电子和空穴，这对提高了复合材料的光催化活性也起到积极的作用。
关键词：二氧化钛 磁载 核壳型 γ-Fe2O3 Fe3O4 光催化 水热合成法
染料废水
ABSTRACT
A series high performance TiO2 photocatalytic composits were prepared and
well-characterized, and their catalytic activities were studied. Based on the
characteristic of prepared nanocomposits, it was systemically discussed that the
crystalline morphology and surface physicochemical properties of the composites were
affected by different coated constitnents and synthesized methods. Moreover, the
photocatalytic activities of as-prepared composites were studies by the degradation of
organic pollutants including methylene blue(MB), rhodamine B(RhB), methyl
orange(MO) and congo red(CR) in the dye wastewater.
New photocatalyst and magnetic, core-shell TiO2 with anatase crystalline phase
such as γ-Fe2O3/SiO2/TiO2、Fe3O4/TiO2 was prepared by hydrothermal treatment
followed by homogeneous precipitation method with ultrasonication. Surface
morphology, crystallize phase and physicochemical properties of the γ-Fe2O3/SiO2/TiO2
core-shell composite were characterized by X-ray diffraction (XRD) patterns, X-ray
photoelectron spectroscopy(XPS), Scanning electron microscope (SEM)and energy
dispersive spectroscopy(EDS) ,Transmission electron microscopy(TEM) and
high-resolution transmission electron microscopy(HRTEM), nitrogen
adsorption/desorption determination and Vibrating Sample Magnetometer (VSM),
Ultraviolet Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS), respectively.
The results show the core-shell γ-Fe2O3/SiO2/TiO2 NP with anatase TiO2 are
composites of spherical nanoparticles about 100nm in diameter, within several
γ-Fe2O3/SiO2 particles about 20nm in diameter and the SiO2 coated on the γ-Fe2O3 with
2nm~6nm, the core-shell γ-Fe2O3/SiO2/TiO2 NP generates red shift,and has higher
absorption in visible light up to a wavelength of 400nm~600nm and greater
photocatalytic activity, and the core-shell γ-Fe2O3/SiO2/TiO2 NP has additional
superparamagetism and can separate and recycle by magnetic, although its magnetism
lower than the the pure γ-Fe2O3 due to the heat treatment at 450℃. And the core-shell
γ-Fe2O3/SiO2/TiO2 NP could be attributed the stronger optical absorption ability, the
higher surface, dual-pore structures.
Furthermore, the efficiency of γ-Fe2O3/SiO2/TiO2 in photocatalytic degradation
was studied by investigating the effects of the Fe/Ti ratios, pH of the reaction solution,
catalyst amount and probably pathways were proposed. About 95% RhB decomposed in
90 min under illumination of UV light. Comparing with the pure TiO2, the high
photoactivity of as-prepared core-shell γ-Fe2O3/SiO2/TiO2 NP could be attributed the
stronger optical absorption ability. γ-Fe2O3/10%SiO2/45%TiO2 has the highest
photoactivity in the condition of pH=2, 2.0g/L γ-Fe2O3/SiO2/TiO2, Fe/Ti =1:1.In
addition, After 5 cycles, the γ-Fe2O3/SiO2/TiO2 NP also maintaines high photocatalytic
activityand catalyst recovery. The core-shell γ-Fe2O3/SiO2/TiO2 composite catalyst also
had the advantages of easily being separated and taken on a wide application prospect.
In this paper, the results show the diameter of the core-shell Fe3O4/TiO2 NP with
anatase TiO2 is about 50nm~100nm, and Fe3O4 core NP is about 20nm~30nm. The
UV-Vis DRS results showed that the core-shell Fe3O4-TiO2 coating consist of FeTiO3,
because the core-shell Fe3O4/TiO2NP has higher absorption in visible light up to a
wavelength of 200nm~700nm and it indicates the synthesis of FeTiO3 NP, which has
good light absorbance and favorable photo-excited electron–hole separation characters.
Furthermore, the band gap of bulk FeTiO3, which is 2.85 eV, is lower than that of TiO2.
In addition, the core-shell Fe3O4/TiO2 NP has additional superparamagetism, And the
core-shell Fe3O4/TiO2 could be attributed the stronger optical absorption ability, the
higher surface, dual-pore structures.
Furthermore, the efficiency of Fe3O4/TiO2 in photocatalytic degradation was
studied by investigating the effects of the Fe/Ti ratios and probably pathways were
proposed. About 95% RhB decomposed in 120 min under illumination of UV light. the
Fe3O4/TiO2 photocatatalytic reaction can be described simply by lnC0/C=kKt=Kappt, and
36.7%Fe3O4/TiO2 (Fe/Ti =1: 2)exhibites the best photocatalytic axtivity and Kapp=0.0332
min-1.
Therefore when core-shell Fe3O4/TiO2 NP is irradiated, the electron possibly
transfers to conduction band in two steps: first step:the electron is initiated from the
valence band to the conduction band of TiO2 and second step: the electron in the
conductionband of TiO2 injects to the conduction band of FeTiO3. For this two-step
mechanism, the lifetime of excited hole and electron pair was prolonged. Perhaps the
improved efficiency of the photon is another reason for the good photocatalytic activity
of the 36.7%Fe3O4/TiO2 coatings.
Key words: TiO2,Magnetic,Core-Shell Structure,γ-Fe2O3, Fe3O4,
Photocatalytic,Programmed Temperature Hydrothermal Treatment,
Dye wastewater
目 录
中文摘要
ABSTRACT
第一章 绪 论 ...................................................................................................................1
1.1 光催化化学 ........................................................................................................... 1
1.2 半导体光催化化学 ............................................................................................... 2
1.2.1 半导体的能带结构 ......................................................................................... 2
1.2.2 半导体光催化基本原理 ................................................................................. 3
1.2.3 半导体金属氧化物光催化研究现状 ............................................................. 5
1.3 磁载核壳型 TiO2复合光催化剂 .......................................................................... 6
1.3.1 磁载核壳型 TiO2复合光催化剂的基本概念 ................................................ 7
1.3.2 核壳型复合光催化剂形成过程及其作用机理 ............................................. 7
1.3.3 磁载核壳型 TiO2复合光催化剂制备方法 .................................................... 8
1.3.3.1 溶胶-凝胶法............................................................................................... 8
1.3.3.2 均相沉淀法 ................................................................................................ 9
1.3.3.3 微乳液法 .................................................................................................... 9
1.3.3.4 原位生长法 .............................................................................................. 10
1.3.3.5 微波水热法 .............................................................................................. 10
1.3.4 核壳型复合光催化剂研究现状 ................................................................... 10
1.4 磁核材料 ............................................................................................................. 12
1.4.1 纳米 Fe3O4的制备与性质 ............................................................................ 13
1.4.2 纳米 γ-Fe2O3的性质 ..................................................................................... 14
1.5 磁载 TiO2复合光催化剂在水处理方面的应用 ................................................ 14
1.6 论文选题目的及意义 ......................................................................................... 16
第二章 磁载核壳型 TiO2复合光催化剂的制备与表征 ..............................................18
2.1 磁载核壳型 TiO2复合光催化剂的制备 ............................................................ 18
2.1.1 实验试剂与仪器 ........................................................................................... 18
2.1.2 磁载核壳型 TiO2复合光催化材料的制备过程 .......................................... 19
2.1.1.1 磁基质(Fe3O4)的制备.............................................................................. 19
2.1.1.2 Fe3O4/SiO2纳米粒子的制备 .................................................................... 20
2.1.1.3 γ-Fe2O3/SiO2/TiO2纳米粒子的制备 ........................................................ 21
2.1.1.4 Fe3O4/TiO2纳米粒子的制备 .................................................................... 22
2.2 磁载核壳型 TiO2复合光催化剂的表征 ............................................................ 23
2.2.1 X 射线粉末衍射光谱（XRD）分析 ............................................................ 23
2.2.2 X 射线光电子能谱(XPS)测试 ...................................................................... 23
2.2.3 扫描电子显微镜（SEM-EDS）分析 .......................................................... 24
2.2.4 透射电子显微镜（TEM）和(HRTEM)分析 .............................................. 24
2.2.5 N2吸附-脱附（N2-adsorption-desorption） ................................................. 24
2.2.6 VSM 分析 ....................................................................................................... 25
2.2.7 紫外可见固体漫反射（UV-Vis DRS）分析 .............................................. 25
第三章 磁载核壳型 γ-Fe2O3/SiO2/TiO2光催化剂结构与光催化性能的研究............27
3.1 γ-Fe2O3/SiO2/TiO2复合光催化剂的结构与讨论................................................ 27
3.1.1 X 射线粉末衍射光谱（XRD）分析 ............................................................ 27
3.1.2 X 射线光电子能谱(XPS)测试 ...................................................................... 28
3.1.3 扫描电子显微镜（SEM） ........................................................................... 30
3.1.4 透射电子显微镜（TEM）和(HREM)分析................................................. 31
3.1.5 N2吸附-脱附（N2-adsorption-desorption） ................................................. 32
3.1.6 VSM 分析 ....................................................................................................... 34
3.1.7 紫外可见固体漫反射（UV-Vis DRS）分析 .............................................. 35
3.1.8 小结 ............................................................................................................... 36
3.2 光催化性能研究 ................................................................................................. 37
3.2.1 实验仪器和试剂 ........................................................................................... 37
3.3.2 光催化反应 ................................................................................................... 38
3.2.3 结果与讨论 ................................................................................................... 39
3.2.3.1 γ-Fe2O3/SiO2/TiO2对不同化学结构染料的光催化活性 ........................ 39
3.2.3.2 γ-Fe2O3/SiO2/TiO2与TiO2的光催化性能的比较 ................................... 43
3.2.3.3 Fe/Ti 比值对 γ-Fe2O3/SiO2/TiO2光催化活性的影响.............................. 43
3.2.3.4 溶液初始 pH 对γ-Fe2O3/SiO2/TiO2光催化活性的影响 ....................... 44
3.2.2.5 γ-Fe2O3/SiO2/TiO2催化剂投加量对光催化活性的影响 ........................ 46
3.2.3.6 γ-Fe2O3/SiO2/TiO2复合光催化剂的再生与循环 .................................... 47
3.3 γ-Fe2O3/SiO2/TiO2光催化反应机理研究............................................................ 48
3.4 小结 ..................................................................................................................... 49
第四章 磁载核壳结构 Fe3O4/TiO2复合光催化材料的结构与光催化性能的研究 ...51
4.1 Fe3O4/TiO2表征结果讨论 ................................................................................... 51
4.1.1 X 射线粉末衍射光谱（XRD）分析 ............................................................ 51
4.1.2 扫描电子显微镜（SEM） ........................................................................... 52
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作者：牛悦
分类：高等教育资料
价格：15积分
属性：79 页
大小：5.82MB
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时间：2025-01-09
