全氟及多氟烷基化合物在羟基氧化与水合电子还原协同作用下的降解机制及QSAR研究

全氟及多氟烷基化合物（PFAS）的降解是近几年国内外的研究热点，但目前尚缺乏PFAS降解行为与其分子特性参数间的定量关系研究，对于评估新生或缺乏实验数据的PFAS在环境中的降解行为仍是巨大挑战。本项目拟以典型PFAS为研究对象，着重研究其在羟基氧化和水合电子还原协同作用下的降解行为，借助电子顺磁共振、竞争动力学和激光闪光光解法定量表征降解过程的自由基，利用高分辨质谱和DFT计算等手段，研究其协同脱氟和降解机制。在此基础上，研究PFAS与羟基和水合电子的亲和力、得失电子情况和键断裂能量的变化规律，借助数学回归削弱非密切相关因子干扰，建立PFAS降解行为的QSAR模型，从分子结构角度揭示影响PFAS降解的内在因子，探索PFAS的降解规律。项目有望提供一种高效脱氟的降解技术，并为预测新生或缺乏实验数据的PFAS的环境降解行为及评估其治理效果提供理论依据，进而指导PFAS污染防控的实际应用。

The degradation of Per- and polyfluoroalkyl Substances (PFAS) has received significant attention in recent years. However, the quantitative relationship between the degradation behaviors and molecular parameters of PFAS remains unknown, which may cause a major challenge to evaluate the degradation behavior of emerging and unexplored PFAS in the environment. In this project, typical PFAS were selected to explore the degradation behaviors in rational integration of oxidation (using heat—activated hydroxyl radical, •OH) and reduction (using UV—generated hydrated electrons, e_aq^-) process. The free radicals in the degradation process were quantitatively tested by electron paramagnetic resonance (EPR), competitive dynamics, and laser flash photolysis. LC—HRMS and transition state theory based on DFT calculation were employed to understand the synergistic defluorination and degradation mechanisms of PFAS. Subsequently, quantum chemical calculations of PFAS were conducted to evaluate the degradation rules, including the affinity between PFAS and •OH and e_aq^- (e.g., dipole moment or Fukui indices), the ability to lose or gain electrons (e.g., the energy HOMO or LUMO), and the indices of bond breaking (e.g., bond order or the total energy of molecule). The QSAR models were established using the degradation behaviors as dependent variables and quantum chemical parameters as independent variables after the irrelevant factors were weakened using mathematical regressions. The developed QSAR model can reveal the influencing factors that affect the degradation of PFAS from the view of molecular structure and can help to better understand the universal degradation rules. This project will not only offer an effective defluorination technology for PFAS degradation, but also provide the theoretical foundation in evaluating the degradation behaviors and treatment of emerging and unexplored PFAS, as well as offer the guide for the practical application of PFAS prevention and control.