载体性质对TiO2光催化反应动力学影响机理研究

TiO2 nano-crystalline materials with specific and special morphology has a very attractive prospect, and in order to further broaden its application, overcome the disadvantages of recycle, the nano morphology is difficult to and to improve the visible light response range, TiO2 need to be modified and supported. However, theoretical studies have shown that there is a band gap energy, impurity distribution level, the nature of impurities, fermions position bandgap energy and other edge factors affecting its photocatalytic reactivity, therefore, from the theoretical grasp the nature of its photocatalytic, the most important step is the process of photocatalytic degradation of its stable intermediates and product separation, purification, structure identification, and establish its degradation kinetics. In this study, a different carrier titanium dioxide as raw material, select compounds with different molecular weights and different nature of their degradation reaction, separation and purification process of degradation intermediates and product stability. On the basis of data obtained intermediate product structure established on the degradation of organic molecules in nano-TiO2 kinetic equation for the in-depth understanding and grasp of improving its photocatalytic reactivity provide theoretical support.

TiO2作为光催化剂有着非常诱人的应用前景。为了进一步拓宽其应用途径，克服其纳米形态难以回收利用的缺点，同时提高其可见光响应范围，需要对TiO2进行改性和负载。理论研究表明有带隙能量、杂质分布水平、杂质性质、费米子的位置与能隙边缘的能量等多个因素影响了它的光催化反应活性。因此，要从理论上掌握其光催化本质，最重要的是对其光催化降解过程中的稳定中间体与产物进行分离、纯化、结构鉴定，然后建立其降解动力学方程。本研究以硅藻土助滤剂、白炭黑、蛋白土、粉煤灰漂珠为载体，制备稀土元素掺杂的纳米TiO2复合光催化剂，以含酚废水为降解对象，对纯纳米TiO2与负载型纳米TiO2对含酚废水的降解过程进行研究，从分子水平上来研究降解反应过程，获得量化数据，以解释纯纳米TiO2与负载型纳米TiO2光催化的动力学过程，进而揭示载体性质对纳米TiO2光催化反应动力学的影响机理。

纳米TiO2在光催化等方面表现出优异的性能，选用具有良好的化学稳定性，内部孔、道数量多，以及表面羟基丰富的硅质矿物作为载体，有助于提高纳米TiO2的稳定性与光催化活性。本项目围绕稀土掺杂的硅质矿物负载型纳米TiO2的制备及负载型纳米TiO2光催化降解小分子有机物的性能方面展开深入研究。本项目的重要研究成果包括五方面内容：（1）分别以白炭黑、硅藻土、蛋白土、粉煤灰漂珠、珍珠岩五种成分相似、结构不同的硅质矿物为载体，负载稀土La/Ce掺杂纳米TiO2，减弱了纳米TiO2的微团聚，提高了纳米TiO2的分散性与稳定性，提升了纳米TiO2复合材料回收及循环再利用的可行性；（2）实现负载型纳米TiO2光催化复合材料制备工艺的简洁化。在制备过程中，应用无溶剂的硅基矿物与钛源直接混合搅拌成浆料，替换传统的“溶胶-凝胶”法，提高制备的原子经济性和安全性；（3）La/Ce掺杂的矿物负载型纳米TiO2显著提高了降解有机小分子的光催化能力，也拓宽了其对可见光的响应范围；（4）构建光催化降解的一级反应动力学方程；（5）探讨了硅质矿物的表面物理化学特性对负载型纳米TiO2光催化降解能力的影响机制，尤其是硅质矿物的表面羟基数，及其内部的孔、道结构的数量与直径大小扮演了很重要的角色。