Premium
Development and validation of a congener‐specific photodegradation model for polybrominated diphenyl ethers
Author(s) -
Zeng Xia,
Simonich Staci L. Massey,
Robrock Kristin R.,
Korytár Peter,
AlvarezCohen Lisa,
Barofsky Douglas F.
Publication year - 2008
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/07-570.1
Subject(s) - photodegradation , polybrominated diphenyl ethers , diphenyl ether , chemistry , decabromodiphenyl ether , environmental chemistry , reaction rate constant , congener , bromine , ether , brominated flame retardant , kinetics , organic chemistry , fire retardant , pollutant , catalysis , photocatalysis , physics , quantum mechanics
With the phaseout of the manufacture of some polybrominated diphenyl ether (PBDE) formulations, namely penta‐brominated diphenyl ether (BDE) and octa‐BDE, and the continued use of the deca‐BDE formulation, it is important to be able to predict the photodegradation of the more highly brominated congeners. A model was developed and validated to predict the products and their relative concentrations from the photodegradation of PBDEs. The enthalpies of formation of the 209 PBDE congeners were calculated, and the relative reaction rate constants were obtained. The predicted reaction rate constants for PBDEs show linear correlation with previous experimental results. Because of their large volume use, their presence in the environment, and/or importance in the photodegradation of the deca‐BDE formulation, BDE‐209, BDE‐184, BDE‐100, and BDE‐99 were chosen for further ultraviolet photodegradation experiments in isooctane. The photodegradation model successfully predicted the products of the photochemical reactions of PBDEs in experimental studies. A gas chromatography retention time model for PBDEs was developed using a multiple linear regression analysis and, together with the photodegradation model and additional PBDE standards, provided a way to identify unknown products from PBDE photodegradation experiments. Based on the results of the photodegradation experiments, as well as the model predictions, it appears that the photodegradation of PBDEs is a first‐order reaction and, further, that the rate‐determining step is the stepwise loss of bromine. Our results suggest that, based on photodegradation, over time, BDE‐99 will remain the most abundant penta‐BDE, while BDE‐49 and BDE‐66 will increase greatly and will be comparable in abundance to BDE‐47.