Cathode-Introduced Atomic H for Fe(II)-Complex Regeneration to Effective Electro-Fenton Process at a Natural pH

Promotion of iron solubility using ligands is the preliminary step in the homogeneous electro-Fenton (EF) process at a mild pH, but the chelate efficiencies of most organic ligands are unsatisfactory, resulting in insufficient Fe­(II) availability. In this study, atomic H* was, for the first time, i...

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Bibliographic Details
Published in:Environmental science & technology 2019-06, Vol.53 (12), p.6927-6936
Main Authors: Liu, Xiao-Cheng, Li, Wen-Qiang, Wang, Yi-Ran, Zhou, Guan-Nan, Wang, Yi-Xuan, He, Chuan-Shu, Wang, Gong-Ming, Mu, Yang
Format: Article
Language:English
Subjects:
Biodegradation
Cathodes
Chelates
Ciprofloxacin
Density functional theory
Electrochemical analysis
Electrochemistry
Electron paramagnetic resonance
Electron spin
Electron spin resonance
Humic acids
In situ leaching
Iron
Leaching
Ligands
Mineralization
Nickel
Organic carbon
pH effects
Pollutants
Regeneration
Spin resonance
Total organic carbon
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Summary:Promotion of iron solubility using ligands is the preliminary step in the homogeneous electro-Fenton (EF) process at a mild pH, but the chelate efficiencies of most organic ligands are unsatisfactory, resulting in insufficient Fe­(II) availability. In this study, atomic H* was, for the first time, introduced to the EF process to accelerate the regeneration of the Fe­(II)-complex at a mild pH using a Ni-deposited carbon felt (Ni-CF) cathode. The introduction of atomic H* significantly elevated total organic carbon (TOC) abatement of ciprofloxacin (CIP) from 42% (CF) to 81% (Ni-CF) at a natural pH. In the presence of humic acids (HAs), atomic H* introduced via Ni-CF enhanced the CIP degradation rate to 10 times that of the CF at a mild pH. The electron spin resonance (ESR), density functional theory (DFT) calculations, electrochemical characterization, and in situ electrochemical Raman study clearly demonstrated that the atomic H* generated from the Ni-CF cathode was highly efficient at reducing Fe­(III)-complexes at a natural pH. Additionally, the Ni-CF could generate atomic H* without significant nickel leaching. Thus, the atomic H* could continuously facilitate iron cycling and, consequently, enhance pollutant mineralization via the homogeneous EF process at a mild pH in an environmentally friendly manner.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b00345