Oxidative Oligomerization of Phenolic Endocrine Disrupting Chemicals Mediated by Mn(III)-L Complexes and the Role of Phenoxyl Radicals in the Enhanced Removal: Experimental and Theoretical Studies.
Environ Sci Technol
; 54(3): 1573-1582, 2020 02 04.
Article
em En
| MEDLINE
| ID: mdl-31886653
ABSTRACT
Soluble manganese(III), stabilized by ligands as Mn(III)-L complexes, are ubiquitous in natural waters and wastewaters and can potentially serve as both the oxidant and reductant in one-electron transfer reactions with organic contaminants. In this study, the oxidative transformations of 14 phenolic endocrine disrupting chemicals (EDCs) by in situ-formed Mn(III)-L complexes, generated from irradiated water containing Mn(II) and humic acid, were investigated. The pseudo-first-order rate constants (kobs, h-1) of these phenols varied from 1.0 × 10-4 to 5.9 × 10-2. A quantitative structure-activity relationship model was developed, which suggests that the electron-donating ability (EHOMO) of phenolic chemicals was the most important molecular characteristic for the Mn(III)-L-mediated oxidative transformation. Phenol transformation was initiated by the generation of a phenoxyl radical through electron transfer to Mn(III)-L. Subsequent self-coupling reactions between phenoxyl radicals resulted in the formation of self-coupling dimers and trimers. With the addition of simple phenol as a cosubstrate, enhanced transformations of these phenolic EDCs were clearly observed, and cross-coupling products of simple phenol and the substrates were also detected. In addition, a reaction activation energy calculation based on the transition-state theory indicated that the cross-coupling reaction was more likely than the self-coupling reaction to occur in the presence of phenol. This work provides new insights into the environmental fate of phenolic compounds.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Disruptores Endócrinos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2020
Tipo de documento:
Article