【作者】 常江；

【导师】 陈强；

【作者基本信息】 兰州大学 ， 环境科学， 2008， 硕士

【摘要】 本论文共分四部分,主要综述了TiO₂光催化反应动力学的研究方法、研究进展以及存在的问题;以甲酸为模型化合物,建立了TiO₂悬浮体系中新的光催化反应动力学模型（Langmuir-Freundlich-Hinshelwood）;应用该模型考察了七种羧酸不同实验条件下光催化降解的动力学规律,并对结果进行了分类比较;讨论了工作中存在的问题并为进一步的研究工作提出建议。第一章对TiO₂光催化氧化技术的起源、应用、反应机理以及光催化反应动力学进行了介绍,其中着重介绍了光催化反应动力学的研究方法,动力学模型的分类以及该领域内存在的问题等。第二章在自制的光催化反应装置内对甲酸进行光催化降解,沿用Langmuir-Hinshelwood模型的建模思路,应用非线性回归的方法,提出TiO₂悬浮体系中新的光催化反应动力学模型（Langmuir-Freundlich-Hinshelwood）。结果表明,该模型的计算值与实验值吻合较好（R²＞0.9）。第三章应用Langmuir-Freundlich-Hinshelwood模型,研究了乙酸、丙酸、乙二酸、丙二酸、丁二酸、酒石酸和苹果酸光催化降解的动力学规律。考察了反应物初始浓度、催化剂浓度、光强和pH值对悬浮体系光催化反应速率常数k的影响,获得了相关参数与反应速率常数间的定量关系。结果表明,物质在催化剂表面的吸附模式是影响反应速率的关键因素,与催化剂表面结合力强的吸附模式将利于物质的降解。催化剂浓度和pH值直接影响所考察物质光催化降解速率的快慢,对于不同的反应物体系,均存在一个最佳值,大于或小于该值都不利于光催化反应速率的提高。光强对反应速率常数k的影响较为一致,均呈现出良好的线性关系。该模型考虑到了催化剂表面的不均匀性以及吸附分子之间的相互作用力等复杂因素。引入的不均匀系数n能较为直观的反映吸附分子与催化剂表面的结合力对光催化反应速率的影响,但仍存在一些缺陷。第四章对本文的研究作一总结,并针对研究中存在的缺陷提出了进一步工作的建议。更多还原

【Abstract】 There are four parts in this dissertation. In the first part, the history, application, mechanism and kinetics of photocatalysis were introduced. The research methods of photocatalytic kinetics and the different kinetic models of photocatalysis were introduced in classification and the defects in this field were evaluated.In the second part, a novel photocatalytic reactor of annulus, which allows the in-situ monitoring of experimental data, has been designed and constructed by us （and validated using formic acid as the model reactant） and a new kinetic model （Langmuir-Freundlich-Hinshelwood） was developed on the basis of the L-H model. The results show that the calculated results obtained from the new kinetic model are in good agreement with experimental data （R²>0.9）.In the third part, the photocatalytic kinetic characteristics of seven carboxylic acids （acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, tartaric acid, malic acid） were investigated, including the dependency of the reaction rate constant k on initial concentration, TiO₂ amount, light intensity and pH. The results showed that their kinetic characteristics under different conditions were successfully described in terms of Langmuir-Freundlich-Hinshelwood model. The relationship between the corresponding parameters and the rate constant k were also determined. The experimental results showed that different adsorption modes were the key factors for the photocatalytic degradation rates. The strong adsorption modes would be favorable to the photocatalytic degradation. TiO₂ amount and pH directly influenced the rate and the optimal reaction conditions were different according to different reaction systems. The influence of light intensity on the chang trend of reaction rate constant k was similar and they had a good linear relationship. Although the heterogeneity of catalysis surface and the adsorption molecules interaction were considered in the new kinetic model and the heterogeneity coefficient n could directly reflect the influence of the bonding force between the catalysis and adsorbs on the rate constant k, there were still some defects in it.In the fourth part, future research direction was pointed out.更多还原