抗癫痫类药物在表层水环境中的间接光解过程机理研究

Pharmaceuticals as one kind of the emerging contaminants have aroused worldwide attention. At present, their removal and transformation in water environment have become one of the research hotspots in the world. The indirect photolysis of antiepileptic drugs (AEDs) was investigated by the combination of transient and stable technologies. In the project, many kinds of photosensitizers including the manmade and natural were used to study the indirect photolysis mechanism of AEDs. The indirect photolysis characteristic and kinetics of AEDs by imitation sunlight were studied. The steady state concentrations of hydroxyl radical, singlet oxygen and triplet photosensitizer were determined by molecule probe technique. The property and kinetics characteristic of transient products waere studied by laser flash photolysis and pulse radiolysis. The effect of different water quality parameters on AEDs indirect photolysis and the relationship between water quality parameters and AEDs indirect photolysis were also investigated in this project. In addition, the photobacteria were used to measure the toxicity of the photolysis products. Meanwhile, to combine the steady state products analysis, the indirect photolysis mechanism was clarified in the project. The aim of the project was to predict the change of indirect photochemistry of AEDs effectively in surface water and to provide scientific foundation for environmental administration to predict the environmental fate and ecological risk assessment of this kind of emerging contaminants.

药物类污染物作为新兴污染物已引起广大环境工作者的广泛关注，其在水环境中的迁移转化已成为目前的研究热点。本项目以环境中广泛存在的抗癫痫类药物（AEDs）为研究对象，选择多种人工和天然光敏化剂，研究AEDs在模拟太阳光作用下的间接光解特性及动力学，并采用分子探针技术测定羟基自由基、单线态氧和三线态光敏化剂等活性粒子的稳态浓度。采用脉冲辐解和激光光解的时间分辨方法对AEDs的瞬态产物进行分析，确定其种类、相应的物理化学参数及瞬态反应动力学。研究不同水质参数对AEDs间接光解的影响，建立各水质参数与AEDs间接光解之间的关联模型。运用发光菌等生物测试手段测定AEDs的光解产物的毒性情况。同时结合光解过程中的稳态产物分析情况，阐明AEDs的间接光解机理。从而有效的预测这类污染物在地表水环境中的间接光化学过程变化，为环保部门预测该类新兴污染物的环境归趋和生态风险评估提供科学依据。

本课题以应用最为广泛的卡马西平（CBZ）、扑米酮（PMD）、苯巴比妥（PBB）和苯妥英（PET）为研究对象，深入研究了抗癫痫药物的光解和电子束辐照降解动力学，机理及产物毒性，所得结果对有效预测这类污染物在地表水环境中的光解作用变化及其环境归趋提供科学依据。主要研究结论为：光解和电子束辐照都是降解抗癫痫药物的有效方法，电子束辐照的效果要好于光解。（1）对CBZ的研究发现，H2O2 和Fe (II)的加入都提高了CBZ的光解率，而且CBZ的光解率随着H2O2 加入量的增多而增大；酸性条件有利于CBZ的光解，无机盐离子的加入抑制了其光解。Fe (II)的最佳浓度为0.5 mM。并对CBZ的光解产物进行分析，提出了可能的光解途径。（2）PBB、PMD和PET的光解都遵循假一级动力学。PBB、PMD和PET的降解率随H2O2 和Fe(II)投加量的增大而增大，随着三种目标物初始浓度的增加而降低；在直接UV和UV / H2O2体系中，中性条件有利于PMD的降解，酸性条件利于PET的降解，碱性条件有利于PBB的降解。Cl-的加入促进了PMD的降解，但抑制了PBB和PET的降解；HCO3-的加入促进了PBB的降解，但抑制了PMD和PET的降解。在UV/ Fe(II)体系下，O2能加快三种目标物的降解。采用IC和LC/MS/MS分析了三种目标污染物经光降解后的阴阳离子及中间产物。根据对降解产物分析结果，提出了PMD、PBB和PET经紫外光解的降解途径。最后，通过发光细菌实验，发现降解产物的毒性随着降解时间的增加先增强后降低。（3）对于CBZ和PMD的电子束辐照降解，发现CBZ和PMD的电子束辐照降解都遵循假一级动力学，且动力学常数随着CBZ和PMD浓度增加呈指数衰减。电子束辐照水体的三种自由基eaq–、•H和•OH是降解CBZ和PMD的关键，且•OH的作用最大，•H其次，eaq–最小。酸性条件和N2O的加入有利于降解。加入适当的H2O2有利于CBZ和PMD降解。酸性条件和氧气的加入有利于降解。根据降解特征和降解中间产物的测定，提出了电子束降解CBZ和PMD降解途径。分别采用培养旋轮虫的和发光菌的方法研究了CBZ和PMD中间产物的毒性，发现产物的毒性作用较小，说明电子束辐照是去除CBZ 和PMD的一种较为安全的手段。