Mechanism insights into the oxidative degradation of decabromodiphenyl ethane by potassium permanganate in acidic conditions

- DBDPE was effectively degraded by KMnO4 in sulfuric acid medium.
- Twenty-eight degradation products of DBDPE were detected.
- Two reaction pathways of DBDPE were proposed.
- Debromination, hydroxylation, direct oxidation, ring-opening were observed.

The KMnO4 degradation of decabromodiphenyl ethane (DBDPE), an additive in brominated flame retardants (BFRs), was investigated in a sulfuric acid system. The degradation tests showed that DBDPE reacted completely with KMnO4 in sulfuric acid, and a removal rate of 99.71% seems realistic. Many products were detected by liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) analysis and gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) analysis. The degradation initially forms 1,2-bis(perbromophenyl)ethane-1,2-dione (P1), pentabromophenol (P2), 2-(perbromophenyl)ethanol (P3) and pentabromobenzoic acid (P28), and the subsequent transformation of these primary intermediates generates ring-opening, five-membered ring and six-membered heterocycle products over time. Two main reaction pathways involving the direct oxidation of the C-C bond of the ethyl group and the cleavage of the C-C bond between ethyl carbon and the adjacent carbon were proposed, and were further confirmed by point charges analyses and Wiberg bond order calculations. Furthermore, the toxicity of DBDPE and its degradation products were evaluated using the ECOSAR program. DBDPE was found to be a toxic substance that could cause great damage to three kinds of organisms in different trophic levels, while all the transformation products were less toxic than parent compound.

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