Transformation of 2,2',4,4'-tetrabromodiphenyl ether under UV irradiation: potential sources of the secondary pollutants.
A commercial brominated flame retardant 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) was used as the model chemical to investigate the degradation and transformation of polybrominated diphenyl ethers (PBDEs) in gas and liquid phases, respectively, under ultraviolet (UV) irradiation. The results showed that BDE-47 can be transformed to less-brominated BDE analogs. A total of six compounds that are less-brominated BDEs and two brominated phenols were observed as transformation products in the reaction mixtures. Different degradation rates of BDE-47 in n-nonane and in isooctane in the same chamber system were observed. Degradation rate of BDE-47 in n-nonane was faster than in isooctane. Under UV irradiation, the bromine on the ortho positions of the phenyl rings was lost first to form 2,4,4'-tribromodiphenyl ether (BDE-28), which then progressively lead to 4,4'-dibromodiphenyl ether (BDE-15) or 2,4'-dibromodiphenyl ether (BDE-8). An airborne transformation pathway has been proposed according to observed transformation products. The more volatile less-brominated BDEs from transformation of BDE-47 are easily evaporated into air to be a source of secondary pollutants in the environment.
Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, Environmental and Radiation Health Sciences Directorate, Health Canada, AL: 0800C, EHC, Tunney's Pasture, Ottawa, Ontario, Canada K1A 0K9.
Ji-Zhong
JZ
Wang
Yuqing
Y
Hou
Jianshun
J
Zhang
Jiping
J
Zhu
Yong-Lai
YL
Feng
D000388:Air; D000393:Air Pollutants / Q000737:chemistry; D000473:Alkanes / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D052918:Environmental Restoration and Remediation / Q000379:methods; D005411:Flame Retardants / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry; D010647:Phenyl Ethers / Q000737:chemistry; D010782:Photolysis; D018570:Risk Assessment; D014466:Ultraviolet Rays
D000393:Air Pollutants; D000473:Alkanes; D004785:Environmental Pollutants; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D010647:Phenyl Ethers; C511295:2,2',4,4'-tetrabromodiphenyl ether; D019800:Phenol; C031538:phenyl ether; C017573:nonane
Air quality; Airborne BDE-47; Degradation and transformation; Pathway; Ultraviolet (UV) irradiation