Distinct photoproducts of hydroxylated polybromodiphenyl ethers from different photodegradation pathways: a case study of 2 '-HO-BDE-68

作者：Xie, Qing; Chen, Jingwen^*; Zhao, Hongxia; Wang, Xingbao; Xie, Hong-Bin

来源：Environmental Science: Processes and Impacts , 2015, 17(2): 351-357.

DOI：10.1039/c4em00395k

• POLYBROMINATED DIPHENYL ETHERS
• WIDELY USED BIOCIDE
• DIBENZO-P-DIOXINS
• PHOTOCHEMICAL FORMATION
• WASTE-WATER
• CHLORINATED DERIVATIVES
• FIELD-MEASUREMENTS
• SURFACE WATERS
• OH-PBDES
• TRICLOSAN

Hydroxylated polyhalodiphenyl ethers (HO-PXDEs) are emerging aquatic pollutants. Previous studies have shown that HO-PXDEs can photogenerate dioxins and phenolic compounds. However, it is unclear which photochemical pathways are responsible for the various photoproducts. This study investigates the direct photolysis and photooxidation initiated by O-1(2) and (OH)-O-center dot that can be formed by photosensitization, taking 2'-HO-2,3',4,5'-tetrabromodiphenyl ether (2'-HO-BDE-68) as a case study. The results show that 1,3,8-tribromodibenzo-p-dioxin can only be produced during direct photolysis. By mass spectrum analysis, four dihydroxylated polybromodiphenyl ethers, generated from both direct and indirect photodegradation were confirmed. Among them, di-HO-tribromodiphenyl ether (di-HO-TBDE) was the main product generated from direct photohydrolysis. Most probably, the di-HO-TBDE is 2',5'-HO-2,3',4-tribromodiphenyl ether, as was suggested by density functional theory calculations. Ether bond cleavage is a dominant pathway for the direct photolysis and photooxidation reactions leading to 2,4-dibromophenol as the dominant product. The yields of the products, which are irrespective of reaction time and can be employed to compare the ability of different HO-PXDEs to photogenerate a given product, were reported. This study indicates that for accurate ecological risk assessment of HO-PXDEs, their different photodegradation pathways that may lead to different photoproducts should be considered.

• 出版日期2015
• 单位大连理工大学