State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Jiangsu, Nanjing, 210023, PR China.
King Saud University, College of Science, Zoology Department, P.O. Box 2455, Riyadh, 11451, Saudia Arabia.
J Hazard Mater. 2019 Oct 15;378:120758. doi: 10.1016/j.jhazmat.2019.120758. Epub 2019 Jun 11.
In this work, the photochemical transformation of decachlorobiphenyl (PCB-209) on the surface of several solid particles were systematically evaluated under simulated solar irradiation. The degradation kinetics of PCB-209 were first investigated using silica as a model aerosol particulate. It was found that PCB-209 photodegradation was enhanced at small silica particle size, low surface coverage and low humidity. Electron paramagnetic resonance (EPR) analysis and radicals quenching experiments demonstrated that hydroxyl radicals contributed to PCB-209 degradation. Stepwise hydrodechlorination, hydroxyl addition and cleavage of the CC bridge bond were mainly observed in the reaction process, leading to the formation of lower chlorinated PCBs, hydroxylated PCBs (OH-PCBs) and chlorophenols. Based on density functional theory (DFT) calculation, the dissociation energy of the CCl bond requires 354.81-359.79 kJ/mol energy that corresponds to a wavelength of less than 322 nm. And the minimum activation energy of OH radicals attack on PCB-209 is only 18.12 kJ/mol. Photochemical transformation of PCB-209 can also occur on the surface of natural particles, but the rates were inhibited as compared to silica. The hydroxylation and hydrodechlorination products of PCB-209 were detected in all natural particles. This study would make significant contribution to understanding the fate of PCBs in solids/air interface.
在这项工作中，系统评估了模拟太阳辐射下几种固体颗粒表面上的十氯联苯（PCB-209）的光化学转化。首先使用二氧化硅作为模型气溶胶颗粒来研究 PCB-209 的降解动力学。结果发现，在小的二氧化硅颗粒尺寸、低表面覆盖率和低湿度下，PCB-209 的光降解得到增强。电子顺磁共振（EPR）分析和自由基猝灭实验表明，羟基自由基对 PCB-209 的降解起作用。在反应过程中，主要观察到逐步脱氯、羟基加成和 CC 桥键的断裂，导致形成低氯代 PCBs、羟基化 PCBs（OH-PCBs）和氯酚。基于密度泛函理论（DFT）计算，CCl 键的离解能需要 354.81-359.79 kJ/mol 的能量，对应于小于 322nm 的波长。而 OH 自由基攻击 PCB-209 的最小活化能仅为 18.12 kJ/mol。PCB-209 的光化学转化也可以在天然颗粒的表面上发生，但与二氧化硅相比，其反应速率受到抑制。在所有天然颗粒中都检测到 PCB-209 的羟基化和脱氯产物。这项研究将对理解 PCBs 在固/气界面上的命运做出重要贡献。
