Li M, An Z, Huo Y, Jiang J, Zhou Y, Cao H, He M. Simulation degradation of bromophenolic compounds in chlorine-based advanced oxidation processes: Mechanism, microscopic and apparent kinetics, and toxicity assessment.
CHEMOSPHERE 2022;
291:133034. [PMID:
34822870 DOI:
10.1016/j.chemosphere.2021.133034]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 05/28/2023]
Abstract
Chlorine-based advanced oxidation processes (AOPs) have been extensively studied to remove contaminants through generating HO• and reactive chlorine species, including ClO• and Cl•. In this work, 2,4,6-tribromoanisole (246TBA) and 2,4,6-tribromophenol (246TBP) were selected as model to investigate the reaction mechanisms and micro-kinetics of brominated contaminants with HO•, ClO• and Cl• in chlorine-based AOPs. Also, the apparent degradation kinetics of two compounds were simulated at pH 3.0-9.5 under UV/H2O2, UV/chlorine and UV/NH2Cl. Calculated results showed that neutral 246TBA and 246TBP exhibited similar reactivity to HO• and ClO•, which was different from anionic 2,4,6-tribromophenolate (246TBPT): radical adduct formation (RAF) and H atom abstraction (HAA) were predominant mechanisms for the HO• and ClO• initiated reactions of 246TBA and 246TBP, while RAF and single electron transfer (SET) for 246TBPT; the reaction rate constants of 246TBA and 246TBP with HO• and ClO• were lower than 107 M-1 s-1, and such rate constants dramatically increased to 1010 M-1 s-1 once 246TBP was deprotonated to 246TBPT. The apparent degradation kinetics of 246TBA at pH 3.0-9.5 was simulated in the order of UV/NH2Cl > UV/chlorine > UV/H2O2, and UV/chlorine and UV/NH2Cl were more effective for the removal of 246TBP and 246TBPT than UV/H2O2. UV and/or Cl• dominated 246 TBA degradation under three AOPs. The main radicals mediating 246TBP and 246TBPT degradation are respectively HO• under UV/H2O2, ClO• under UV/chlorine, and HO• and Cl• under UV/NH2Cl. The transformation products of 246TBA, 246TBP and 246TBPT, especially methoxylated and hydroxylated polybrominated diphenyl ethers (MeO-PBDEs and HO-PBDEs), were still toxic pollutants.
Collapse