OH-initiated degradation of 2,2′,4,4′,5,6′-hexabrominated diphenyl ether (BDE-154) in the atmosphere and wastewater: Mechanisms, kinetics, and ecotoxicity

In the present work, the reaction mechanism and kinetics of 2,2′,4,4′,5,6′-hexabrominated diphenyl ether (BDE-154) with OH were researched by employing density functional theory (DFT) and transition state theory (TST). The gas-phase and aqueous solution reaction mechanisms and kinetic parameters were computed at the level of M06–2X/6–311++G (3df, 3pd)//M06–2X/6-311G (d,p). The OH-addition of the non-bromine replaced carbon atom of the aromatic ring in BDE-154 is superior to substitution and H-abstraction mechanisms. The secondary reaction referring to OH-addition adducts in the existence of O₂/NO will generate tribromophenol and OH-addition products. The majority of conversion products are still poisonous to hydrobiont. The KiSThelP program was applied to assess the overall rate coefficient and the individual rate coefficient at 258–328 K of 760 Torr. The overall rate coefficient at 298 K and 760 Torr are 9.40 × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ and 3.60 × 10⁶ M⁻¹ s⁻¹ in atmosphere and wastewater. The half-lives are 123.1 days and 1.93 × 10²-1.93 × 10¹¹ s, respectively. These results elucidated the conversion mechanism, atmospheric fate and ecotoxicity of BDE-154 in advanced oxidation procedure.