Photoreductive Debromination of Decabromodiphenyl Ethers in the Presence of Carboxylates under Visible Light Irradiation
Photoreductive Debromination of Decabromodiphenyl Ethers in the Presence of Carboxylates under Visible Light Irradiation
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可见光照射下羧酸盐存在下十溴二苯醚的光还原脱溴
DOI：
10.1021/es3045604
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发表时间：
2013-03-05
影响因子：
11.4
通讯作者：
Zhao, Jincai
中科院分区：
文献类型：
--
作者：
Sun, Chunyan;Chang, Wei;Zhao, Jincai
多溴联苯醚（PBDEs）因其广泛存在于生物和环境系统中，具有毒性，已引起全球环境关注。因此，寻找一种有效的去污方法，了解它们在环境中的化学转化是非常重要的。在此，我们报告，十溴二苯醚（BDE-209）在环境介质中常见的各种羧酸根阴离子存在下，在可见光照射（>= 420 nm）下发生有效的还原脱溴反应。脱溴反应是逐步进行的，产生一系列溴化程度较低的多溴二苯醚同系物。在光反应过程中，通过自旋捕获电子自旋共振（ESR）实验观察到溶剂衍生的辐射。通过紫外-可见吸收光谱和等温滴定量热法（ITC）的进一步实验，结合理论计算，揭示了一种新的基于卤素结合相互作用的光化学脱溴途径。根据这一途径，虽然PBDE和羧酸盐都没有可见光吸收，但PBDE和羧酸盐之间形成基于卤素结合的复合物使PBDE能够吸收可见光并脱溴。基于卤键的光化学脱溴方法可以更好地了解PBDEs在环境中的转化过程。
Polybrominated diphenyl ethers (PBDEs) have aroused global environmental concerns because of their toxicity and ubiquitousness in the biological and environmental systems. It is important to find an efficient method for their decontamination and to understand their chemical transformation in the environment. Here, we report that decabromodiphenyl ether (BDE209) undergoes efficient reductive debromination reactions under visible-light irradiation (>= 420 nm) in the presence of various carboxylate anions that are common in the environmental media. The debromination reactions occur in a stepwise manner, producing a series of lower brominated PBDE congeners. Solvent-derived radials are observed by spin-trapping electron spin resonance (ESR) experiments during the photoreaction. Further experiments by the UV-vis absorption and isothermal titration calorimetry (ITC), combined with theoretical calculations, reveal a new photochemical debromination pathway based on the halogen binding interaction. According to this pathway, the formation of halogen-binding-based complex between PBDE and carboxylate enables the visible-light absorption and debromination of PBDEs, although neither PBDEs nor carboxylates have visible-light absorption. The halogen-bond-based photochemical debromination could find its application for our better understanding of the transformation process of PBDEs in the environment.