TiO2@SiO光催化降解不同染料及其机理研究

Study on TiO2@SiO2 photocatalytic degradation of different dyes and its mechanism

摘要:

本文制备了不同Ti负载量的TiO2@SiO2复合材料，通过SEM、XRD、BET、XPS和光谱分析手段对TiO2@SiO2复合材料的微观形貌、晶体结构、化学组成及光学性质进行分析，并进行不同染料的光催化降解实验。结果表明复合材料为球形核壳结构的锐钛矿型TiO2，比表面积较大，光学响应范围蓝移。TiO2与载体SiO2之间形成Ti-O-Si键结构，有助于光生电子空穴的分离，促进活性氧的生成，TiO2与SiO2相界面间产生的缺陷和畸变形成较多的氧空位，也有助于催化降解。实验对比了甲基橙(MO)和罗丹明B (RhB) 两种染料的降解过程，发现复合材料的吸附作用对染料分子的降解速率和降解途径均有明显的影响，复合材料表面的负电位对RhB分子的二乙氨基有强烈吸附作用并使该基团首先解离，促使该溶液发生了特征蓝移效应，吸附与活性氧协同作用加速了染料分子的降解。通过清除剂实验还证明，在可见光下MO和RhB染料溶液降解过程中超氧自由基是最主要的活性物质，其他种类的活性氧起到了辅助的作用。本论文研究内容有助于了解不同染料的吸附降解过程，同时促进光催化技术在污水处理中的应用。

Abstract:

In this paper, TiO2@SiO2 composite materials with different Ti contents were prepared. The microscopic morphology, crystal structure, chemical composition and optical properties of TiO2@SiO2 composite materials were analyzed by SEM, XRD, BET, XPS ,DRS and spectral analysis method, and photocatalytic degradation experiments were carried out. The results showed that the sample is anatase TiO2 with a spherical core-shell structure, a large specific surface area and blue shift of light response range. XPS showed that the Ti-O-Si bond is formed between TiO2 and SiO2. Ti-O-Si bond contributed to the separation of photogenerated electrons holes, and further promoted the generation of superoxide radicals in active oxygen during the photocatalytic degradation process. Due to defects and distortions produced at the interface between TiO2 and SiO2 phases, there are more oxygen vacancies were generated at the interface, thereby organic pollutants are degraded. The degradation processes of methyl orange and rhodamine B dyes were compared, it showed that the adsorption of the composite material has a significant effect on the degradation rate and degradation pathways of the dye molecules. The negative potential on the surface of the composite material strongly adsorbs the diethylamino group of the RhB molecule and dissociates the group first, and it promotes the occurrence of the characteristic blue shift effect of the solution. The synergistic effect of adsorption and active oxygen accelerates the degradation of dye molecules. The scavenger experiment also proved that the superoxide radical is the most important active substance in the degradation process of MO and RhB dye solution under visible light, and other kinds of active oxygen play an auxiliary role. The research content of this work reveals the adsorption and degradation process of different dyes, and promote the application of photocatalytic technology in sewage treatment。