全卤代羧酸污染物在BiOCl表面的高效光催化降解及其机理研究

The perhalocarboxylate acids such as perfluorooctanoic acid have attracted increasing concerns as a kind of persistent organic pollutants. However, the traditional advanced oxidation techniques including TiO2 photocatalysis exhibit limited effectiveness for their degradation. The preliminary study by the applicants of this project found that BiOCl photocatalyst is able to degrade efficiently the perfluorooctanoic acid and trichloroacetic acid under UV irradiation with wavelength larger than 360 nm. From this observation as starting point, the present project would compare systematically the adsorption and degradation mechanism for the degradation of perhalocarboxylate acids on BiOCl and TiO2. The surface microstructure and the mechanism for two photoinduced hole transfer channels of the direct oxidation pathway of perhalocarboxylate acids and the activation of solvent water molecules into OH radicals on these two photocatalysts would also be investigated. The key mechanism for the effective photocatalytic degradation of perhalocarboxylate acids on BiOCl would be elucidated. After that, the strategy to improve the degradation efficiency and selectivity of perhalocarboxylate acids would be developed by control of the surface state and design of new photocatalyst. This project would be very helpful for the development of new systems and new techniques for the selective degradation of perhalocarboxylate acids pollutants.

全卤代羧酸化合物（如全氟辛酸）是近年来备受环境化学领域关注的持久性污染物，但是传统的高级氧化技术，包括TiO2光催化技术，对它们的降解效果非常有限。申请者初步研究发现在波长大于360纳米的紫外光的照射下BiOCl光催化剂可以非常有效将全氟辛酸和三氯乙酸光催化氧化降解。本项目将以此观察为切入点，系统研究全卤代羧酸污染物在BiOCl和TiO2表面的吸附和降解机理的差别，研究在光催化剂表面直接氧化全卤代酸和将溶剂水活化为羟基自由基这两个光生空穴转移通道的微观结构和机理。揭示BiOCl高效光催化降解全卤代羧酸污染物的关键机制，在此基础上探索提高全卤代羧酸污染物降解效率和选择性的催化剂表面调控途径和新型光催化剂的设计原理，发展选择性降解全卤代羧酸污染物的新体系和新技术。

本项目设计合成了系列基于BiOCl的光催化新材料和新体系，揭示了基于BiOCl的系列高效光催化降解全卤代羧酸污染物的关键机制，阐明了全卤代羧酸污染物在BiOCl和TiO2表面的吸附和降解机理的差别，揭示了不同光生空穴转移通道的微观结构和反应机理。深入研究了TiO2光催化还原脱卤过程中的电子转移与质子转移机理，阐明了表面质子调控机制及其在卤代污染物光催化脱卤过程中的重要作用。研究成果将为高效降解全卤代羧酸污染物新材料新体系的设计提供方法学及理论支撑。在Appl. Catal. B: Environ.、Coll. Surf. A、Appl. Surf. Sci.等国际SCI期刊上发表相关论文23篇。培养博士研究生2名，硕士研究生2名。