Screening Refractory Dye Degradation by Different Advanced Oxidation Processes

This study investigated Rhodamine B (RhB) degradation by electro-Fenton (EF), anodic oxidation (AO), and their combination (EF/AO), using a carbon felt cathode coupled to a sub-stoichiometric titanium dioxide Magnéli phase (Ti<sub>4</sub>O<sub>7</sub>) anode or a platinized t...

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Main Authors: Imane Ouagued, Marc Cretin, Eddy Petit, Geoffroy Lesage, Abderrahmane Djafer, Abdallah Ouagued, Stella Lacour
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/3/712
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author Imane Ouagued
Marc Cretin
Eddy Petit
Geoffroy Lesage
Abderrahmane Djafer
Abdallah Ouagued
Stella Lacour
author_facet Imane Ouagued
Marc Cretin
Eddy Petit
Geoffroy Lesage
Abderrahmane Djafer
Abdallah Ouagued
Stella Lacour
author_sort Imane Ouagued
collection DOAJ
description This study investigated Rhodamine B (RhB) degradation by electro-Fenton (EF), anodic oxidation (AO), and their combination (EF/AO), using a carbon felt cathode coupled to a sub-stoichiometric titanium dioxide Magnéli phase (Ti<sub>4</sub>O<sub>7</sub>) anode or a platinized titanium (Ti/Pt) anode. The results indicated that operational parameters influenced the kinetics of electrochemical reactions. An increase in current density from 10 to 50 mA cm<sup>−2</sup> significantly enhanced the RhB degradation rate; 30 mA cm<sup>−2</sup> was the optimal current density, balancing both energy efficiency and degradation performance. Moreover, higher RhB concentrations required longer treatment. The Microtox<sup>®</sup> bioluminescence inhibition test revealed a significant toxicity decrease of the dye solution during electrochemical degradation, which was highest with EF/AO. Similarly, total organic carbon removal was highest with EF/AO (90% at pH 3), suggesting more efficient mineralization of RhB and its by-products than with EF or AO. Energy consumption remained relatively stable with all oxidation processes throughout the 480 min electrolysis period. High-resolution mass spectrometry elucidated RhB degradation pathways, highlighting chain oxidation reactions leading to the formation of intermediates and mineralization to CO<sub>2</sub> and H<sub>2</sub>O. This study underscores the potential of EF, AO, and EF/AO as effective methods for RhB mineralization to develop sustainable and environmentally friendly wastewater treatment strategies.
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spelling doaj-art-66eead110c4f4ae2b908e3a2a396e4342025-08-20T03:12:35ZengMDPI AGMolecules1420-30492025-02-0130371210.3390/molecules30030712Screening Refractory Dye Degradation by Different Advanced Oxidation ProcessesImane Ouagued0Marc Cretin1Eddy Petit2Geoffroy Lesage3Abderrahmane Djafer4Abdallah Ouagued5Stella Lacour6Water–Environment Laboratory, Hassiba Benbouali University, Chlef 02000, AlgeriaEuropean Institute of Membranes, IEM UMR-5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, FranceEuropean Institute of Membranes, IEM UMR-5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, FranceEuropean Institute of Membranes, IEM UMR-5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, FranceWater–Environment Laboratory, Hassiba Benbouali University, Chlef 02000, AlgeriaWater–Environment Laboratory, Hassiba Benbouali University, Chlef 02000, AlgeriaEuropean Institute of Membranes, IEM UMR-5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, FranceThis study investigated Rhodamine B (RhB) degradation by electro-Fenton (EF), anodic oxidation (AO), and their combination (EF/AO), using a carbon felt cathode coupled to a sub-stoichiometric titanium dioxide Magnéli phase (Ti<sub>4</sub>O<sub>7</sub>) anode or a platinized titanium (Ti/Pt) anode. The results indicated that operational parameters influenced the kinetics of electrochemical reactions. An increase in current density from 10 to 50 mA cm<sup>−2</sup> significantly enhanced the RhB degradation rate; 30 mA cm<sup>−2</sup> was the optimal current density, balancing both energy efficiency and degradation performance. Moreover, higher RhB concentrations required longer treatment. The Microtox<sup>®</sup> bioluminescence inhibition test revealed a significant toxicity decrease of the dye solution during electrochemical degradation, which was highest with EF/AO. Similarly, total organic carbon removal was highest with EF/AO (90% at pH 3), suggesting more efficient mineralization of RhB and its by-products than with EF or AO. Energy consumption remained relatively stable with all oxidation processes throughout the 480 min electrolysis period. High-resolution mass spectrometry elucidated RhB degradation pathways, highlighting chain oxidation reactions leading to the formation of intermediates and mineralization to CO<sub>2</sub> and H<sub>2</sub>O. This study underscores the potential of EF, AO, and EF/AO as effective methods for RhB mineralization to develop sustainable and environmentally friendly wastewater treatment strategies.https://www.mdpi.com/1420-3049/30/3/712electrochemical advanced oxidation processeselectro-Fentonanodic oxidationcoupling processecotoxicitymineralization
spellingShingle Imane Ouagued
Marc Cretin
Eddy Petit
Geoffroy Lesage
Abderrahmane Djafer
Abdallah Ouagued
Stella Lacour
Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
Molecules
electrochemical advanced oxidation processes
electro-Fenton
anodic oxidation
coupling process
ecotoxicity
mineralization
title Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
title_full Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
title_fullStr Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
title_full_unstemmed Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
title_short Screening Refractory Dye Degradation by Different Advanced Oxidation Processes
title_sort screening refractory dye degradation by different advanced oxidation processes
topic electrochemical advanced oxidation processes
electro-Fenton
anodic oxidation
coupling process
ecotoxicity
mineralization
url https://www.mdpi.com/1420-3049/30/3/712
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AT marccretin screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses
AT eddypetit screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses
AT geoffroylesage screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses
AT abderrahmanedjafer screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses
AT abdallahouagued screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses
AT stellalacour screeningrefractorydyedegradationbydifferentadvancedoxidationprocesses