School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou, 510006, China.
J Hazard Mater. 2018 Jun 15;352:165-171. doi: 10.1016/j.jhazmat.2018.03.038. Epub 2018 Mar 21.
Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants that are ubiquitous in the environment. The physical and chemical properties of PBDEs make them difficult to degrade, with the conventional remediation methods being relatively inefficient. In this study, the reactivity of zero valent zinc (ZVZ) toward 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) was evaluated under aqueous solution. First-order rate constants (k) for BDE-47 disappearance increased with decreased pH, which is attributed to the dissolution of surface zinc oxides that promote the contact between the active site on zinc surface and BDE molecules. The k of ten investigated PBDEs in ZVZ system are positively correlated with the energy of lowest unoccupied orbitals (E) of PBDEs (R = 0.902). The debromination pathways of BDE-47 in ZVZ system are: BDE-47 → BDE-28 → BDE-15 → BDE-3 → DE, which is the same to the debromination pathways of BDE-47 in zero valent iron (ZVI) in previous study. In addition, the singly occupied molecular orbitals (SOMOs) of the BDE anions can well reflect the actual debromination pathways of PBDEs by comparing the size of the CBr antibonding characterized lobes. Our results suggest that the debromination of PBDEs by ZVZ is based on the electron transfer mechanism, and the SOMOs of BDE anions can be used to predict the debromination pathways of untested PBDEs.
多溴二苯醚（PBDEs）是一类溴系阻燃剂，广泛存在于环境中。PBDEs 的物理和化学性质使其难以降解，传统的修复方法效率相对较低。本研究评估了零价锌（ZVZ）在水溶液中对 2,2',4,4'-四溴二苯醚（BDE-47）的反应活性。BDE-47 消失的一级速率常数（k）随 pH 值的降低而增加，这归因于表面氧化锌的溶解，促进了锌表面活性位点与 BDE 分子之间的接触。在 ZVZ 体系中，十种被研究的 PBDEs 的 k 与 PBDEs 的最低未占据轨道能量（E）呈正相关（R=0.902）。ZVZ 体系中 BDE-47 的脱溴途径为：BDE-47→BDE-28→BDE-15→BDE-3→DE，与之前在零价铁（ZVI）中研究的 BDE-47 的脱溴途径相同。此外，通过比较 CBr 反键特征叶的大小，可以很好地反映 BDE 阴离子的实际脱溴途径，从而反映出 BDE 阴离子的占据分子轨道（SOMOs）。我们的结果表明，ZVZ 对 PBDEs 的脱溴是基于电子转移机制，并且 BDE 阴离子的 SOMOs 可用于预测未经测试的 PBDEs 的脱溴途径。
