Mechanisms and pathways of ethidium bromide Fenton-like degradation by reusable magnetic nanocatalysts

Chemosphere. 2021 Jan:262:127852. doi: 10.1016/j.chemosphere.2020.127852. Epub 2020 Jul 31.

Abstract

Ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanthridinium bromide, EtBr) is a carcinogenic compound widely used for staining nucleic acids that is difficult to treat. In this study, magnetic nanocatalysts (MNCs) were synthesized for the heterogeneous Fenton-like degradation of EtBr. The initial pH, MNC content, and H2O2 concentration were the key factors affecting the EtBr degradation performance and dynamics. An EtBr removal efficiency of 98.97% was achieved within 4 h under optimal conditions (initial pH, 3.0; MNC content, 1 g/L; H2O2 concentration, 50 mM), and the degradation followed the ring-open pathway with (2E,4Z,8E)-3-amino-N-ethyl-7,9-dihydroxynona-2,4,8-trienamide as an intermediate, as determined by liquid chromatography and mass spectrometry (LC/MS). Unexpected and satisfactory Fenton-like oxidation of EtBr occurred under basic conditions, which was explained by a novel denitration pathway with 2-[nitro(phenyl)methyl]-(1,1'-biphenyl)-4,4'-diamine as an intermediate. The MNCs retained 62.17% of their degradation efficiency after five consecutive reaction and harvest cycles. Our work elucidated the mechanisms and pathways of EtBr removal in a Fenton-like reaction using MNCs, and comprehensively discussed the optimal reaction conditions and its potential for re-use.

Keywords: Ethidium bromide; Fenton-like reaction; Hydrogen peroxide; Magnetic nanocatalysts.

MeSH terms

  • Ethidium / chemistry*
  • Hydrogen Peroxide / chemistry
  • Hydrogen-Ion Concentration
  • Magnetic Phenomena
  • Mass Spectrometry
  • Oxidation-Reduction

Substances

  • Hydrogen Peroxide
  • Ethidium