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| 2. |
- Christiansson, Anna, et al.
(författare)
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Identification and quantification of products formed via photolysis of decabromodiphenyl ether
- 2009
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 16:3, s. 312-321
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND, AIM, AND SCOPE: Decabromodiphenyl ether (DecaBDE) is used as an additive flame retardant in polymers. It has become a ubiquitous environmental contaminant, particularly abundant in abiotic media, such as sediments, air, and dust, and also present in wildlife and in humans. The main DecaBDE constituent, perbrominated diphenyl ether (BDE-209), is susceptible to transformations as observed in experimental work. This work is aimed at identifying and assessing the relative amounts of products formed after UV irradiation of BDE-209. MATERIALS AND METHODS: BDE-209, dissolved in tetrahydrofuran (THF), methanol, or combinations of methanol/water, was exposed to UV light for 100 or 200 min. Samples were analyzed by gas chromatography/mass spectrometry (electron ionization) for polybrominated diphenyl ethers (PBDEs), dibenzofurans (PBDFs), methoxylated PBDEs, and phenolic PBDE products. RESULTS: The products formed were hexaBDEs to nonaBDEs, monoBDFs to pentaBDFs, and methoxylated tetraBDFs to pentaBDFs. The products found in the fraction containing halogenated phenols were assigned to be pentabromophenol, dihydroxytetrabromobenzene, dihydroxydibromodibenzofuran, dihydroxytribromodibenzofuran, and dihydroxytetrabromodibenzofuran. The PBDEs accounted for approximately 90% of the total amount of substances in each sample and the PBDFs for about 10%. DISCUSSION: BDE-209 is a source of PBDEs primarily present in OctaBDEs but also to some extent in PentaBDEs, both being commercial products now banned within the EU and in several states within the USA. It is notable that OH-PBDFs have not been identified or indicated in any of the photolysis studies performed to date. Formation of OH-PBDFs, however, may occur as pure radical reactions in the atmosphere. CONCLUSIONS: Photolysis of decaBDE yields a wide span of products, from nonaBDEs to hydroxylated bromobenzenes. It is evident that irradiation of decaBDE in water and methanol yields OH-PBDFs and MeO-PBDFs, respectively. BDE-202 (2,2',3,3',5,5',6,6'-octabromodiphenyl ether) is identified as a marker of BDE-209 photolysis. RECOMMENDATIONS AND PERSPECTIVES: BDE-209, the main constituent of DecaBDE, is primarily forming debrominated diphenyl ethers with higher persistence which are more bioaccumulative than the starting material when subjected to UV light. Hence, DecaBDE should be considered as a source of these PBDE congeners in the environment
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| 3. |
- Christiansson, Anna, et al.
(författare)
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Methods for synthesis of nonabromodiphenyl ethers and a chloro-nonabromodiphenyl ether
- 2006
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Ingår i: Chemosphere. ; 63:4, s. 562-569
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Tidskriftsartikel (refereegranskat)abstract
- Polybrominated diphenyl ethers (PBDEs) have been used extensively as brominated flame retardants (BFRs) in textiles, upholstery and electronics. They are ubiquitous contaminants in wildlife and humans. A low concentration of nonabrominated diphenyl ethers (nonaBDEs) is present in commercial DecaBDE and they are also abiotic and biotic debromination products of decabromodiphenyl ether (BDE-209). The objective of the present work was to develop methods for synthesis of the three nonaBDEs, 2,2',3,3',4,4',5,5',6-nonabromodiphenyl ether (BDE-206), 2,2',3,3',4,4',5,6,6'-nonabromodiphenyl ether (BDE-207) and 2,2',3,3',4,5,5',6,6'-nonabromodiphenyl ether (BDE-208), with the intention of making them available as authentic standards for analytical, toxicological and stability studies, as well as studies regarding physical-chemical properties. Two methods were developed, one based on perbromination of phenoxyanilines and the other via reductive debromination of BDE-209 by sodium borohydride followed by chromatographic separation of the three nonaBDE isomers formed. An additional nonabrominated compound, 4'-chloro-2,2',3,3',4,5,5',6,6'-nonabromodiphenyl ether (Cl-BDE-208), was also synthesized in the present work. Cl-BDE-208, prepared by the perbromination of 4-chlorodiphenyl ether, may be used as an internal standard in analysis of highly brominated diphenyl ethers. BDE-206, BDE-207, BDE-208 and Cl-BDE-208 were characterized by 1H NMR, 13C NMR, electron ionization mass spectra and by their melting points. The structures of all three nonaBDEs have been characterized previously by X-ray crystallography.
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| 4. |
- Eriksson, Johan, et al.
(författare)
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Photochemical decomposition of fifteen polybrominated diphenyl ether congeners in methanol/water
- 2004
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Ingår i: Environmental Science & Technology. - : American Chemical Society. - 1520-5851 .- 0013-936X. ; 38:11, s. 3119-3125
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Tidskriftsartikel (refereegranskat)abstract
- Among all brominated flame retardants in use, the polybrominated diphenyl ethers (PBDEs) have been identified as being of particular environmental concern due to their global distribution and bioaccumulating properties, as observed in humans and wildlife worldwide. Still there is a need for more data on the basic characteristics of PBDEs to better understand and describe their environmental fate. Hence, the aim of this study was to investigate the photochemical degradation of PBDEs with different degrees of bromination. The photochemical degradation of 15 individual PBDEs substituted with 4−10 bromine atoms was studied in methanol/water (8:2) by UV light in the sunlight region. Nine of these were also studied in pure methanol, and four of the nine PBDEs were studied in tetrahydrofuran. The photochemical reaction rate decreased with decreasing number of bromine substituents in the molecule but also in some cases influenced by the PBDE substitution pattern. The reaction rate was dependent on the solvent in such a way that the reaction rate in a methanol/water solution was consistently around 1.7 times lower than in pure methanol and 2−3 times lower than in THF. The UV degradation half-life of decaBDE (T1/2 = 0.5 h) was more than 500 times shorter than the environmentally abundant congener 2,2‘,4,4‘-tetraBDE (T1/2 = 12 d) in methanol/water. The quantum yields in the methanol/water solution ranged from 0.1 to 0.3. The photochemical reaction of decaBDE is a consecutive debromination from ten- down to six-bromine-substituted PBDEs. Products with less than six bromines were tentatively identified as brominated dibenzofurans and traces of what was indicated as methoxylated brominated dibenzofurans.
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| 6. |
- Eriksson, Johan, et al.
(författare)
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Photochemical transformations of tetrabromobisphenol A and related phenols in water
- 2004
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535. ; 54:1, s. 117-126
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Tidskriftsartikel (refereegranskat)abstract
- romobisphenolA (TBBPA), tribromobisphenol A (TriBBPA), tetrachlorobisphenol A (TCBPA), 2,4-dichlorophenolat various pHs as well as 2-chlorophenol, 2-bromophenol, 3,4-dichlorophenol and bisphenol A at pH 11. The absorbancespectra of the compounds and the emission spectra of the light-source were determined and used to calculatedisappearance quantum yields of the photochemical reactions that were taking place. No major differences between thedisappearance quantum yields of TBBPA and TCBPA were observed at pH 10, while the disappearance quantum yieldof TriBBPA was approximately two times higher. The rate of decomposition of TBBPA was six times higher at pH 8than at pH 6. Identification of the degradation products of TBBPA and TriBBPA, by GC–MS analysis and bycomparison to synthesised reference compounds, indicated that TBBPA and TriBBPA decompose via differentmechanisms. Three isopropylphenol derivatives; 4-isopropyl-2,6-dibromophenol, 4-isopropylene-2,6-dibromophenoland 4-(2-hydroxyisopropyl)-2,6-dibromophenol, were identified as major degradation products of TBBPA while themajor degradation product of TriBBPA was tentatively identified as 2-(2,4-cyclopentadienyl)-2-(3,5-dibromo-4-hydroxyphenyl)propane.
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| 7. |
- Eriksson, Johan, 1956-
(författare)
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Polybrominated diphenyl ethers and Tetrabromobisphenol A : Chemical synthesis, X-ray crystallography and Photochemical degradation
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the 1960s’ several manmade chemicals were detected in the environment, far from their sources. The most well known, and most likely those with the largest impact on the society, were DDT and its related compounds, and PCBs. These anthropogenic compounds were characterised as persistent organic pollutants (POPs). Following these POPs, several other chemicals have found their way to the environment. Over the last two decades, brominated flame retardants (BFRs) have become a matter of concern. Among all BFRs being commercially produced, tetrabromobisphenol A (TBBPA) and polybrominated diphenyl ethers (PBDEs) are the ones with the largest annual production. TBBPA is a very well defined compound while PBDEs consist of a large number of isomers and homologues (congeners). TBBPA does not seem to accumulate in biota as the PBDEs do, but is still of concern since it is found in e.g. sediments. The PBDEs can reach accumulation levels up in the ppm range. Still there is a lack of basic data for both TBBPA and PBDEs. Hence the present thesis is aimed to fill some of the data gaps by pursuing work on 1) photochemical degradation of TBBPA, some related compounds, and PBDEs; 2) synthesis of PBDE congeners and of TBBPA degradation products and 3) structural identifications of a selected set of BFRs by X-ray crystallography.An apparatus was designed for carrying out photochemical degradation test of chemicals in general but in particular for BFRs. Quantum yield, rate of degradation and to some extent, identification of degradation products were performed on TBBPA, the corresponding chlorinated compound and a number of TBBPA degradation products and on 15 single PBDE congeners. In order to make this work possible all three nonaBDE isomers were synthesised via a reductive pathway applying sodium borohydride as a reducing agent. The three nona-BDEs were all characterised by X-ray crystallography. The results of the photochemical degradation of TBBPA in water show a rapidly degradable compound also at pH’s that are environmentally relevant. Hence it is likely that TBBPA is not transported long distances, when exposed to sunlight, without undergoing photochemical degradation. It is notable that the TBBPA is degraded through cleavage between the two phenol rings. When the method was applied to study quantum yields and rate constants for the reaction of PBDE congeners it is evident that the decabromodiphenyl ether (BDE-209) is rapidly transformed. The reaction rate differ drastically from PBDEs with four or five bromine substituents that have very long half-lives when subjected to UV-light under the same conditions as for BDE-209. Lower brominated diphenyl ethers and polybrominated dibenzofurans were identified as PBDE degradation products. The synthesis of PBDEs and of TBBPA degradation products expanded the study as did the X-ray structure identifications.
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| 9. |
- Granelli, Lisa, 1979-
(författare)
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Chemical reactivities as a mirror of environmental transformations - method development and assessment of some selected organohalogens
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The assement of chemical persistence is an important part of legislative protection of the environment and human health. Of the vast number of chemicals on the market today few have been properly assessed. The coordination between testing guidelines from different frameworks is limited and especially the methods for determination of biodegradation show poor reproducibility because of their highly complex nature. In order to circumvent the multifactorial assessment methods that involve the use of e.g. soils and sediments an attempt to create a new approach to chemicals assessment was postulated by Green and Bergman in 2005. This approach puts the focus on testing the chemical reactivity of the compound in environmentally relevant transformation/degradation reactions, i.e. reduction, oxidation, hydrolysis-substitution-elimination (hse), radical reactions, and photolysis. These tests are to be performed in controlled abiotic laboratory experiments ensuring that the results reflect the transformation rate of the intended type of reaction for the investigated substance. To achieve an assessment of the presistence of the compound, the test results are then combined with data on physicochemical properties of the compound and a mathematic matrix describing the reactive power of the different types of reactions in each environmental compartment (air, water, soil, and sediment). Thus far methods for testing of oxidation, photolysis, and hydrolysis-substitution-elimination reactions have been developed. Within this thesis a method for determining reduction was developed and further utilised to determine transformation products from reductive debromination of the three nonabrominated diphenyl ethers. The previously established method for hse was evaluated and further developed in a study of selected chlorobenzenes. Some novel brominated flame retardants were investigated using the previously developed photolysis method, and transformation products and quantum yields were determined. All of the papers presented within this thesis intend to build on the project of a new persistency assessment model. The results presented also contributes important information on the properties and transformation of some common organohalogen pollutants.
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