碳酸根自由基的光化学生成、淬灭及其对胺类药物的降解研究

Carbonate radical ion (CO3•-) is one of important reactive oxygen species (ROS), which presents relative high concentration in the natural surface water. It could be raised from quenching hydroxyl radical or direct reaction from triplet state of natural organic matters (3NOM*) with bicarbonate/carbonate. In general, carbonate radical oxidizes organic contaminates through electron or H transfer, and more selective than hydroxyl radical. Due to lacking of chemical probe and complex matrix effects, there is a few studies regarding the degradation of contaminates by carbonate radical. Our project will focus on the photochemical formation and trapping of carbonate radical in the natural and contaminated waters, furthermore to explore the reaction kinetics and degradation mechanism of carbonate radical with amino-pharmaceuticals. Firstly varied organic components will be separated from natural water, contaminated water and effluents from wastewater treatment plants. Then the photochemical formation and quenching rate constants of carbonate radical will be measured using new chemical probe. The apparent quantum yields will be further determined. Based on the above results, we will try to build up the relationship between organic matters composition with the steady state concentrations of carbonate radical under simulated solar irradiation. Moreover, 9 amino-pharmaceuticals will be selected in this study. The reaction rate constants will be measured by competition studies, and the degradation mechanism will be explored by LC-QTOF MS. The role of carbonate radical in the photo-transformation of PPCPs will be elucidated. Overall this proposal seeks to develop a comprehensive understanding of the formation, quenching and reactivates of carbonate radical. Our research output will be valuable to predict the environmental fate of emerging contaminates. Therefore, to provide the scientific evidences for regulatory groups to assess the environmental risks for emerging contaminates.

碳酸根自由基是一类重要的光敏化活性氧物种，广泛存在于地表水环境体系中。然而由于缺乏相应的研究手段，目前关于碳酸根自由基在太阳光照水体中的生成及淬灭机制研究较少，并且关于其对水体污染物的降解机理的研究报道更为罕见。本课题拟采用不同来源的水体有机质，测定其在太阳光照条件的光敏化碳酸根自由基的生成和淬灭的反应动力学常数、光量子产率，建立水体理化指标与光照水体中碳酸根自由基稳态浓度之间的内在联系，揭示不同水体有机质构成对碳酸根自由基的产生和淬灭机理。研究水体有机质在高浓度碳酸氢根存在下的，光敏化降解、转化动力学和降解机理。并以此为基础，以9种水体中常见的胺类药物污染物为研究对象，测定其与碳酸根自由基的反应动力学参数，并以此为基础预测碳酸根自由基对此类污染物的降解贡献率。运用高分辨质谱揭示碳酸根自由基与此类污染物的降解机理。本研究成果可为更好的理解并预测污染物在自然界中的光降解归趋提供理论依据。

本项目系统研究了碳酸根自由基在太阳光照自然水体中的生成和淬灭机制机理，并以含氮类有机污染物为研究对象（多种药物类和个人护理品类、藻类毒素），研究了其与碳酸根自由基反应的动力学、降解机理。取得研究成果总结如下：1：建立了碳酸根自由基与水体有机质二级反应速率常数的测定方法，测定了不同来源有机质与其二级反应速率常数，并建立了以水体有机质的光化学性质E2/E3来预测其与碳酸根自由基二级反应速率常数的预测公式。2：探究了碳酸根自由基促进水体有机质光漂白速率的机理，并在此基础上发展了碳酸根自由基稳态浓度的计算公式。3：以30多种胺类药物类和个人护理品类污染物为研究对象，采用激光闪光光解法精确测定了其与碳酸根自由基的二级反应速率常数，并应用到高级氧化水处理公式计算中，计算并报道了碳酸根自由基在不同高级氧化水处理体系中的作用。4：以藻类毒素为研究对象，探究了其与碳酸根自由基的反应动力学和反应机理，并首次发现在碳酸根氧化体系中，水体有机质存在着对污染物的“抑制效应”，可使污染物与碳酸根自由基表观二级反应速率常数变低，从而抑制藻毒素的降解。本研究成果可为理解并预测碳酸根自由基参与下的污染物在自然光降解和水处理体系中的归趋提供理论依据。本课题按照计划执行，发表SCI论文11篇，其中以第一作者身份完成Environ. Sci. & Technol.文章1篇，Water Res. 文章1篇，共同通讯作者身份完成Sci. Total Environ.文章1篇。