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31.
Unprecedented total mineralization of atrazine and cyanuric acid by anodic oxidation and electro-Fenton with a boron-doped diamond anode 总被引:1,自引:0,他引:1
This article reports the complete mineralization of atrazine. Atrazine has been the most widely used s-triazine herbicide.
Atrazine occurs in natural waters and presents a potential danger for public health because atrazine is considered as an endocrine
disruptor. The use of chemical, photochemical and photocatalytic advanced oxidation processes (AOPs) to decontaminate waters
containing atrazine only allowed its conversion into the cyanuric acid as ultimate end products, since it cannot be completely
degraded by hydroxyl radicals (•OH) produced by these techniques. The same behavior was previously reported for anodic oxidation and electro-Fenton with Pt
anode, although better performances were found using boron-doped diamond (BDD) anode but without explaining the role of generated
•OH. Here, the oxidative action of these radicals in such electrochemical AOPs has been clarified by studying the mineralization
process and decay kinetics of atrazine and cyanuric acid in separated solutions by anodic oxidation with BDD and electro-Fenton
with Pt or BDD anode using an undivided cell with a carbon-felt cathode under galvanostatic conditions. Results showed that
electro-Fenton with BDD anode was the more powerful treatment to degrade both compounds. Almost total mineralization, 97%
total organic carbon (COT) removal, of atrazine was only feasible by this method with a faster removal of its oxidation intermediates
by •OH formed at the BDD surface than that formed in the bulk from Fenton reaction, although the latter process caused a more
rapid decay of the herbicide. Cyanuric acid was much slowly mineralized mainly with •OH produced at the BDD surface, and it was not degraded by electro-Fenton with Pt anode. These results highlight that electrochemical
advanced oxidation processes (EAOPs) using a BDD anode are more powerful than the classical electro-Fenton process with Pt
or PbO2 anodes. 相似文献
32.
Olvera-Vargas Hugo Leroy Sébastien Rivard Michael Oturan Nihal Oturan Mehmet Buisson Didier 《Environmental science and pollution research international》2016,23(22):22691-22700
Environmental Science and Pollution Research - Some widely prescribed drugs are sparsely metabolized and end up in the environment. They can thus be a focal point of ecotoxicity, either themselves... 相似文献
33.
Murati M Oturan N Aaron JJ Dirany A Tassin B Zdravkovski Z Oturan MA 《Environmental science and pollution research international》2012,19(5):1563-1573
Introduction
The degradation and mineralization of two triketone (TRK) herbicides, including sulcotrione and mesotrione, by the electro-Fenton process (electro-Fenton using Pt anode (EF-Pt), electro-Fenton with BDD anode (EF-BDD) and anodic oxidation with BDD anode) were investigated in acidic aqueous medium.Methods
The reactivity of both herbicides toward hydroxyl radicals was found to depend on the electron-withdrawing effect of the aromatic chlorine or nitro substituents. The degradation of sulcotrione and mesotrione obeyed apparent first-order reaction kinetics, and their absolute rate constants with hydroxyl radicals at pH?3.0 were determined by the competitive kinetics method.Results and discussion
The hydroxylation absolute rate constant (k abs) values of both TRK herbicides ranged from 8.20?×?108 (sulcotrione) to 1.01?×?109 (mesotrione) L?mol?1?s?1, whereas those of the TRK main cyclic or aromatic by-products, namely cyclohexane 1,3-dione , (2-chloro-4-methylsulphonyl) benzoic acid and 4-(methylsulphonyl)-2-nitrobenzoic acid, comprised between 5.90?×?108 and 3.29?×?109?L?mol?1?s?1. The efficiency of mineralization of aqueous solutions of both TRK herbicides was evaluated in terms of total organic carbon removal. Mineralization yields of about 97?C98% were reached in optimal conditions for a 6-h electro-Fenton treatment time.Conclusions
The mineralization process steps involved the oxidative opening of the aromatic or cyclic TRK by-products, leading to the formation of short-chain carboxylic acids, and, then, of carbon dioxide and inorganic ions. 相似文献34.
Removal of methyl parathion from water by electrochemically generated Fenton's reagent 总被引:3,自引:0,他引:3
The electro-Fenton process was used to assess the degradation of methyl parathion (MP) in aqueous solutions. This oxidation process allows the production of hydroxyls radicals which react on the organic compounds, leading to their mineralization. Degradation experiments were performed either in perchloric, sulphuric, hydrochloric and nitric acid media under current controlled electrolysis conditions at different pH. The pH effect as well as the nature of the medium (i.e., the nature of the ions present in medium) on the degradation and mineralization efficiency were studied. The mineralization of the initial pollutant was investigated by total organic carbon measurements which show a complete mineralization at pH 3 in perchloric medium. The absolute rate constant of MP hydroxylation reaction was determined as (4.20+/-0.11)x10(9)M(-1)s(-1). Complete degradation of MP and its metabolites occur in less than 45min. Degradation reaction intermediates such as aromatic compounds, carboxylic acids and inorganic ions were identified and a mineralization pathway is proposed. 相似文献