羟基自由基引发多溴联苯醚替代品的大气转化机制及动力学

Emerging brominated flame retardants and organophosphorus flame retardants as the alternatives of polybrominated diphenyl ethers (PBDEs) have been frequently detected in the atmosphere. Especially in the polar region, their detected concentration was even higher than that of widely concerned PBDEs. Now, the alternatives of PBDEs have become the pollutants with potential environmental risk. According to the general knowledge on transformation of organic pollutants in the atmosphere and the structural feature of the alternatives of PBDEs, the reactions of the alternatives of PBDEs with ?OH should be their important removal way. Therefore, in the view of the environmental risk evaluation on the pollutants, it is essential to reveal the atmospheric chemistry of alternatives of polybrominated diphenyl ethers initiated by ?OH. In this project, the quantum chemical calculation and kinetic modeling are used to 1) investigate the reaction mechanism and kinetics of the representative alternatives of PBDEs with ?OH and ensuing reactions of the produced active radicals including isomerization, dissociation, and bimolecular reaction with O2/NO, to predict their atmospheric lifetime and product distribution; 2)explore the influence of water, which is an important component in the atmosphere, on the above reaction process to better understand the transformation of the alternatives of PBDEs in the real atmospheric environment. The results will be significant for the environmental risk evaluation about the alternatives of PBDEs, and enrich the knowledge about the effect of water on the transformation of organic pollutants in the atmosphere.

多溴联苯醚替代品(新型溴代阻燃剂和有机磷阻燃剂)在大气环境中已被频繁检出，特别是在极地地区，其检出浓度已超过被广泛研究的多溴联苯醚，成为一种具有潜在环境风险的污染物。根据有机污染物大气转化的一般规律及这些替代品的分子结构特征，它们与OH自由基反应将是其大气转化的重要途径。因此，从污染物环境生态风险评价角度来看，揭示OH自由基引发这些替代品的大气化学具有重要意义。本项目拟采用量子化学计算和微观动力学模拟相结合的方法，研究OH自由基与代表性替代品的反应机制、动力学及其生成产物在大气环境中(O2/NO)的进一步转化机制、动力学，以确定替代品的大气寿命及产物分布；研究大气中的水对代表性替代品大气转化的影响机制，以更好地理解它们在实际大气中的转化。研究结果对于多溴联苯醚替代品的环境风险评价及增强水对大气污染物转化影响的理解具有重要意义。

探究大气环境中甚至极地大气中频繁检出的多溴联苯醚替代品(AFRs)及备受关注的短链氯代石蜡的大气化学过程，对其环境生态风险评价具有重要意义。项目采用量子化学计算及微观动力学模拟相结合的手段，研究了•OH引发的三种AFRs(大气中频繁检出且结构具有代表性的磷酸三苯酯(TPhP)、磷酸三(2-氯丙基)酯(TCPP)、1,2-双(2,4,6-三溴苯氧基)乙烷(BTBPE))及短链氯代石蜡(SCCPs, C10-C13)的大气转化机制及动力学。研究发现•OH与TPhP反应最可行的路径是加成到-OR苯环对位的C原子上；TCPP与•OH的反应中摘氢反应是最可行的；对于与PBDEs结构相似的BTBPE，揭示了与PBDEs+•OH反应机制不同的烷基碳链上的摘氢反应路径。•OH引发反应生成的活性自由基会进一步转化，研究也探讨了这些自由基与O2/NOx(x =1,2)的反应动力学及最后产物。基于计算的总包反应速率常数，评估298K条件下AFRs大气寿命，其中TPhP和BTBPE分别约为7.6和11.8天，首次阐明了TPhP和BTBPE气相反应会导致其大气持久性；TCPP为1.7小时，推测导致其大气持久性的原因可能为非均相反应；另外，构建了可用于便捷高效地预测SCCPs的kOH值的QSAR模型。同时，本项目重点以TPhP为例，使用不同的大气水模型，研究了水对•OH引发TPhP大气化学反应的影响，发现不同形态的水对自由基引发的TPhP的转化过程的影响并不显著。. 综上，项目成果揭示了•OH引发AFRs和SCCPs的大气微观转化机制、动力学、产物分布及大气寿命；构建了可用于便捷高效地预测SCCPs kOH值的QSAR模型，阐明了水对•OH引发反应的影响机制，达到了课题的预期目标。部分研究成果发表在国际重要学术刊物Environmental Science & Technology(1篇)和Science of the Total Environment(1篇)上，另外，3篇文章在投，其中1篇投稿于RSC advances期刊，目前处于修改(小修)状态中。