天然碳材料中持久性自由基形成机制及其介导典型溴代阻燃剂转化机理研究

The transformation, fate, and ecotoxicity of brominated flame retardants (BFRs) in environment has been highly concerned due to their toxicity bioaccumulation and long-distance migration. Carbon materials, which are ubiquitous existence in natural environments, have been widely used in the removal of organic and inorganic contaminants for their excellent adsorption abilities. Recent studies indicated that carbon materials could directly or indirectly influence the migration and transformation of emerging organic contaminants (EOCs) for their abundant persistent free radicals (PFRs). Unfortunately, the serious lack of efficient in situ experimental techniques makes it difficult to understand the formation and transformation mechanism of PFRs in carbon materials. In this study, various carbon materials containing different kinds of PFRs were synthesized to systemically investigate the formation mechanism of PFRs with laser flash photolysis, electron spin resonance, three-dimensional excitation emission matrix fluorescence spectroscopy, and solid-state nuclear magnetic resonance. The degradation of BFRs mediated by PFRs in carbon materials was investigated simultaneously to clarify the interaction mechanism between PFRs and BFRs. The quantum chemical calculations and intermediate products analysis will be applied to reveal the degradation mechanism of BFRs and the computational toxicology will be further utilized to investigate the toxicity of degradation intermediates. Simultaneously, the influence of light on the degradation of BFRs in the presence of carbon materials will be studied with laser flash photolysis. This study will not only help us to understand the formation and transformation of PFRs in carbon materials and the interaction mechanism between EOCs and carbon materials, but also the further utilization of carbon materials in natural environment for the remediation of environment contamination and the protection of environmental health.

溴代阻燃剂作为一类典型新兴有机污染物，在自然环境中的迁移、归趋和生态毒性备受关注。天然碳材料因含有大量持久性自由基，能直接或间接参与新兴有机污染物的迁移转化过程。但是持久性自由基的形成和转化机理及其与污染物的相互作用机制尚未明晰，且缺乏有效的原位监测手段。本研究利用激光闪光光解仪原位监测持久性自由基的动力学形成过程，并结合电子顺磁共振等现代表征技术，系统研究其形成机理；以溴代阻燃剂为模型污染物，揭示其与持久性自由基的相互作用机制，结合量子化学计算和中间产物实验检测，阐明其降解路径，并采用计算毒理学揭示降解产物毒性演变特征；分析体系中电子转移和活性物种形成路径，在分子水平上揭示持久性自由基的转化机制；同时利用激光闪光光解仪研究不同波段光照对持久性自由基形成和转化以及溴代阻燃剂降解过程的影响，揭示光照和天然碳材料的协同作用机制，以期进一步深入理解碳材料对环境水体中新兴有机污染物迁移转化的影响。

本项目制备了多种碳材料，并研究了影响碳材料中持久性自由基类型和浓度的关键因素，同时分析了持久性自由基和碳材料表面官能团对其活性的影响。碳中心自由基和表面羟基在是影响碳材料活性的关键因素。同时研究了甲草胺在紫外光下的光化学降解机理，并揭示了生物炭对甲草胺光化学转化过程的影响机制。借助激光闪光光解仪研究了甲草胺的光化学降解动力学，并鉴别了光化学降解过程中的瞬态中间产物。同时利用制备液相色谱分离出了甲草胺光化学降解的中间产物，结合液相色谱飞行时间质谱联用仪和核磁共振仪确定了降解产物的结构，从而更清晰的阐明了甲草胺直接光化学降解的途径和机理。总结了生物炭在环境污染修复、土壤改良和应对全球气候变化等环境应用方面的研究报道，系统分析了生物炭制备和使用过程中可能造成的环境危害和生态风险。研究了不同温度（300、500和700 ℃）下合成的三种生物炭和抗生素青霉素钾对黑麦草生长的协同作用机制。研究了生物炭和青霉素钾共同作用下，黑麦草根长、株高、生物量和抗氧化酶活性的变化，并与生物炭或青霉素钾单独暴露下的生长状况对比，阐明生物炭对抗生素青霉素钾毒性的影响。