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Degradation and Mechanism Characteristics of Polybrominated Diphenyl Ethers (PBDEs)

Author: ShiWenYan
Tutor: WuMingHong
School: Shanghai University
Course: Environmental Engineering
Keywords: Electron beam Photocatalysis 4 - polybrominated diphenyl ethers DecaBDE Laser photolysis
CLC: X132
Type: PhD thesis
Year: 2008
Downloads: 783
Quote: 3
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Abstract

This paper summarizes the persistent organic pollutants in water - polybrominated diphenyl ethers (PBDEs) characteristics, sources, research progress, governance profile and electron beam, ultraviolet degradation of persistent organic pollutants in water pollution control in the research progress made the purpose and significance of this study. Thesis consists of two parts: the use of ultraviolet light or electron beam degradation of 4 - PBDEs mechanism, kinetics and its influencing factors; ultraviolet photolysis or electron beam radiolysis decaBDE degradation mechanism, kinetics and its influencing factors, through the four - polybrominated diphenyl ether and decabromodiphenyl ether these two types of brominated diphenyl ethers and UV photolysis of organic matter degradation characteristics of electron beam analysis, suggesting that polybrominated diphenyl ethers and electronic UV photolysis beam characteristics and degradation pathways. (A) under anaerobic conditions, four - polybrominated diphenyl ethers in the radical cation generated under UV irradiation, the cation radical formation rate k = 2.67 × 10 ^{6 s ^{-1 < / sup> · mol ^{-1 · dm ^{3 . When the four - polybrominated diphenyl ether solution of pH> 10.02,4 - polybrominated diphenyl ethers under ultraviolet irradiation produced radical cation deprotonation to neutral radicals. Certainly strong ultraviolet range 4 - polybrominated diphenyl ethers photolysis products of diphenyl ether and biphenol two organics. Initially speculated that anaerobic conditions, neutral 4 - polybrominated diphenyl ether solution of 4 - polybrominated diphenyl ethers produce ultraviolet liberated bromine radical cation, and further reaction of benzene, ether and biphenol and other more stable intermediate. 4 - polybrominated diphenyl ether solution system, initial pH, initial concentration and exposure time of four - the degradation of polybrominated diphenyl ethers. Using electron beam degradation of 4 - polybrominated diphenyl ethers. The results show that the electron beam on four - debromination of polybrominated diphenyl ethers, and thus degradation has a distinct role. Experiments discussed further 4 - PBDEs solution system, initial pH, initial concentration and irradiation dose of four - the degradation of polybrominated diphenyl ethers. (2) using the UV photolysis decabromodiphenyl ether. The results showed that decaBDE with a 4 - polybrominated diphenyl ethers photolysis characteristics similar to decaBDE debromination under ultraviolet irradiation, and thus degradation. Further experiments are discussed, decaBDE photolysis intermediates and photolysis mechanism in combination with four - PBDEs degradation mechanism, suggesting that PBDEs photolysis mechanism and characteristics. Decabromodiphenyl ether solution system, the initial pH value and exposure time on decaBDE degradation effects. Degradation of decaBDE, bromide ions are removed, as lower brominated diphenyl ethers. Using electron beam degradation of decaBDE. The results show that electron beam decaBDE debromination, and thus degradation has a distinct role. Further experiments are discussed, decabromodiphenyl ether solution system, initial pH, radiolysis dose decaBDE degradation of. (3) using a variety of analytical tools (UV-VIS, pH, GC, HPLC, GC-MS) to determine the electron beam or ultraviolet oxidation degradation of PBDEs two intermediates. 4 - PBDEs degradation process, mainly analyzed three kinds of intermediate products: diphenyl ether, diphenyl and o-hydroxy-hydroxy biphenyl. And speculated that the four - polybrominated diphenyl ethers major degradation pathway. DecaBDE in the degradation process, mainly analyzed two kinds of intermediate products: diphenyl ether, eight polybrominated diphenyl ethers. And speculated decaBDE major degradation pathway.}}}}

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