PARENT SESSION

1B+C Abiotic Transformation + Biodegradation
Hall 9
1:45 PM - 3:30 PM, Monday, 28 April 2003
Chair: Peijnenburg, W.¹, ¹
Co-chair: Jafvert, C.T.², Gombar, V.K.³, ^{2 3}

(MO9/12) UV-spectra, quantum yields and kinetics of photolytic degradation of polybrominated diphenylethers.

Palm, Wolf-Ulrich ¹, Kopetzky, Raimo¹, Ruck, Wolfgang¹, Zetzsch, Cornelius², ¹ University of Lüneburg, Lüneburg, Lower Saxony, Germany² Fraunhofer Institute for Toxicology and Aerosol Research, Hannover, Lower Saxony, Germany

ABSTRACT- Several studies have provided indications that DecaBDE can undergo photolytic degradation under certain conditions. UV-spectra of monobromo to decabromo substituted diphenylethers (PBDEs), dissolved in tetrahydrofuran, kinetics of the photolysis of decabromodiphenylether and corresponding debrominated products and quantum yields of various brominated diphenylethers were investigated, using well defined light intensities of a filtered Xe lamp as solar simulator. PBDEs with N(Br)=0 to N(Br)=10 from commercial and photolysis mixtures were separated within 25 minutes by HPLC. Assignment of congeners was performed by comparison with reference compounds, commercial mixtures of PBDE and available information by GC-MS. Unknown peaks are assigned at least with respect to the degree of bromination. From the UV-spectra of the congeners with N(Br) = 0,1,2,4,6,10 a linear dependence of the integral of molar absorption coefficients versus wavenumber between 280 - 340 nm was found and used to normalize UV-spectra obtained from mixtures resolved by HPLC and determined by a diode array detector. Photolysis of decabromodiphenylether was performed using a 1000 W Xe-light source using optical filters with different cut-off wavelengths. Light intensities were determined using the ferri-oxalate actinometer. Because of the low water solubility of decabromo diphenylether, tetrahydrofuran and acetonitrile were used as models for unpolar and polar solvents. Subsequent debromination was found and kinetic models using parallel and consecutive reaction schemes are discussed, including solvent effects. Experimental values are compared with available data for halogenated aromatic compounds and are used to calculate lifetimes for typical sunlight intensities.

Key words: flame retardants, polybromiated diphenylethers, photolysis quantum yields, HPLC