有机芳香污染物氧化芳环开环机理的研究

The oxidative cleavage of aromatic ring of aromatic organic pollutants is one of the most important processes during their oxidative transformation in environment and their degradation by advanced oxidation technique. It is also essential step to their mineralization to CO2 and H2O. However, the mechanism for cleavage of aromatic ring is not clear so far, and there is much dispute among the past reports. In this proposal, we will select some model aromatic pollutants with characteristic substitutents to investigate the detailed mechanism of their aromatic ring cleavage. The primary employed techniques are isotope tracing and electron spin resonance measurement. The other advanced techniques such as chromatogram-mass spectra, in-situ IR spectra, laser Raman spectra and DFT calculation are also used identify the structure of reaction products and the reaction process. The prelminary aromatic cleavage in some typical oxidation systems such as semiconductor photocatalysis and (like)Fenton reaction will be highlighted. The emphesis will be focused on uncovering the the roles of the solvent water and molecular oxygen in the aromactic cleavage. The specific pathway for C-C bond fission, inserting of the oxygen atom will be elucidated. These studies would be helpful for our understanding on the transformation of the aromatic pollutants in environment, and would be a fundamental guide for developing more efficient advanced oxidation techniques.

含芳香环有机污染物的氧化开环去芳香化是这类污染物在环境中氧化转化和通过高级氧化技术氧化降解的最重要过程之一，也是这些污染物最终矿化为CO2和H2O必需的步骤，但目前对着其氧化开环的机理尚不清楚，且存在争议。本项目将选择具有特征取代基的目标芳香污染物，利用同位素标记示踪、电子顺磁共振方法，结合色谱-质谱联用仪、原位红外光谱、激光拉曼光谱及DFT计算等产物和物质结构现代分析手段，研究在典型氧化体系（如半导体光催化, (类)Fenton等高级氧化体系）中芳香环的初级开环过程，重点研究溶剂水、分子氧在芳香污染物氧化开环过程中的作用，及其导致芳香环中C-C的断裂和氧元素插入过程中各类活性物种的作用及反应路径等机理细节。为研究芳香污染物在环境中的氧化转化提供机理参考，为开发有更高矿化效率高级氧化技术力提供理论依据。

本项目选择了一系列具有特征取代基芳香化合物（如硝基苯，多溴联苯醚等）作为目标污染物，利用同位素标记、电子顺磁共振、色谱-质谱联用仪、原位红外光谱、激光拉曼光谱及DFT 计算等现代产物分析和结构表征手段，研究了半导体光催化过程中芳香环的初级开环过程，包括芳香环的羟基化过程、C-C断裂的开环过程，重点研究了溶剂水、分子氧在芳香污染物氧化开环过程中的作用，证明了分子氧在光催化芳环开环过程中起到至关重要的作用，进一步阐明了开环过程是通过单氧原子插入机理进入到产物中实现的，并且证明了质子转移在含芳环污染物开环过程中的重要作用。在Angew. Chem. Int. Ed.、Environ. Sci. Technol.、Appl. Catal. B: Environ.等国际SCI期刊上发表相关论文12篇。培养博士研究生5名。