Shih Yang-hsin, Wang Chun-Kang
Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung, Taiwan, ROC.
J Hazard Mater. 2009 Jun 15;165(1-3):34-8. doi: 10.1016/j.jhazmat.2008.09.103. Epub 2008 Oct 4.
Polybromodiphenyl ethers (PBDEs) are widely used flame retardant additives and have been mainly used in polymers for many plastic and electronic products. PBDEs have been found to bioaccumulate in both aquatic and terrestrial ecosystems and even human bodies. The technical product with the highest use is decabrominated diphenyl ether (BDE-209). Therefore, we chose to examine the solar and UV-lamp degradation of BDE-209. A linear increase of the photodegradation rate constant for BDE-209 was observed with the solar light intensity. The degradation reactions follow the pseudo-first-order kinetics. The photodegradation of BDE-209 produced other less brominated diphenyl ethers under ultraviolet light exposure, suggesting that the photodegradation of BDE-209 is a sequential dehalogenation mechanism. BDE-209 underwent rapid reductive debromination in these photodecomposition experiments. The formation rate constants of three nonabromodiphenyl ethers increase with the order of BDE-206, BDE-207 and BDE-208, indicating debromination mainly occurred at para>meta>ortho positions. These findings of the process properties and reductive debromination mechanism of the photolytic degradation of PBDEs can facilitate the design of remediation processes and also aid in predicting their fate in the environment.
多溴二苯醚（PBDEs）是广泛使用的阻燃添加剂，主要用于许多塑料和电子产品的聚合物中。人们发现PBDEs会在水生和陆地生态系统甚至人体中生物累积。使用量最高的工业产品是十溴二苯醚（BDE-209）。因此，我们选择研究BDE-209在太阳光和紫外灯下的降解情况。观察到BDE-209的光降解速率常数随太阳光强度呈线性增加。降解反应遵循准一级动力学。在紫外线照射下，BDE-209的光降解产生了其他溴化程度较低的二苯醚，这表明BDE-209的光降解是一种顺序脱卤机制。在这些光分解实验中，BDE-209经历了快速的还原脱溴反应。三种九溴二苯醚的生成速率常数按BDE-206、BDE-207和BDE-208的顺序增加，表明脱溴主要发生在对位>间位>邻位。这些关于PBDEs光解降解过程特性和还原脱溴机制的研究结果有助于修复工艺的设计，也有助于预测它们在环境中的归宿。
