Chlorinated Byproduct Formation during the Electrochemical Advanced Oxidation Process at Magnéli Phase Ti4O7 Electrodes.
Environ Sci Technol
; 54(19): 12673-12683, 2020 10 06.
Article
em En
| MEDLINE
| ID: mdl-32841010
ABSTRACT
This research investigated chlorinated byproduct formation at Ti4O7 anodes. Resorcinol was used as a model organic compound representative of reactive phenolic groups in natural organic matter and industrial phenolic contaminants and was oxidized in the presence of NaCl (0-5 mM). Resorcinol mineralization was >68% in the presence and absence of NaCl at 3.1 V/SHE (residence time = 13 s). Results indicated that â¼4.3% of the initial chloride was converted to inorganic byproducts (free Cl2, ClO2-, ClO3-) in the absence of resorcinol, and this value decreased to <0.8% in the presence of resorcinol. Perchlorate formation rates from chlorate oxidation were 115-371 mol m-2 h-1, approximately two orders of magnitude lower than reported values for boron-doped diamond anodes. Liquid chromatography-mass spectroscopy detected two chlorinated organic products. Multichlorinated alcohol compounds (C3H2Cl4O and C3H4Cl4O) at 2.5 V/SHE and a monochlorinated phenolic compound (C8H7O4Cl) at 3.1 V/SHE were proposed as possible structures. Density functional theory calculations estimated that the proposed alcohol products were resistant to direct oxidation at 2.5 V/SHE, and the C8H7O4Cl compound was likely a transient intermediate. Chlorinated byproducts should be carefully monitored during electrochemical advanced oxidation processes, and multibarrier treatment approaches are likely necessary to prevent halogenated byproducts in the treated water.
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Base de dados:
MEDLINE
Assunto principal:
Titânio
/
Poluentes Químicos da Água
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article