Molecular structure-dependent bioelectrochemical decolorization of azo dyes.

Bibliographic Details
Title: Molecular structure-dependent bioelectrochemical decolorization of azo dyes.
Authors: Yang HY; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China; Pollution Control and Resource Utilization in Industrial Parks Joint Laboratory of Anhui Province, Hefei, China. Electronic address: younghy@ahjzu.edu.cn., Geng X; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China., Quan ZD; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China., Yu L; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China., Huang XH; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China., Li WH; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China., Xue TZ; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China., Mu Y; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China.
Source: Bioelectrochemistry (Amsterdam, Netherlands) [Bioelectrochemistry] 2026 Aug; Vol. 170, pp. 109229. Date of Electronic Publication: 2026 Jan 19.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Elsevier Country of Publication: Netherlands NLM ID: 100953583 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1878-562X (Electronic) Linking ISSN: 15675394 NLM ISO Abbreviation: Bioelectrochemistry Subsets: MEDLINE
Imprint Name(s): Original Publication: [Amsterdam?] : Elsevier, 2000-
MeSH Terms: Azo Compounds*/chemistry , Azo Compounds*/metabolism , Azo Compounds*/isolation & purification , Electrochemical Techniques*/methods , Water Pollutants, Chemical*/chemistry , Water Pollutants, Chemical*/isolation & purification , Coloring Agents*/chemistry, Kinetics ; Electrodes ; Molecular Structure
Abstract: Azo dyes, containing one or more azo bonds (-N=N-), are widely used but pose environmental and health risks due to their toxicity and resistance to degradation. Bioelectrochemical systems (BESs) offer a potential approach for their reductive degradation, yet the role of molecular structure in degradation remains unclear. In this study, nine representative azo dyes were examined to access how substituent type and position affect degradation kinetics and electron transfer under controlled cathodic potentials in BESs. Electron-withdrawing substituents (e.g., -SO3-, -NO2) and o-/m- substitution enhanced azo bond cleavage, while p-substitution or steric hindered degradation. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed that higher reduction currents and lower charge-transfer resistance correlated with faster degradation. Quantitative structure-activity relationship (QSAR) analysis identified that the -N=N- group and other molecular features such as atom count, are key determinants of azo dyes removal. Experimental and theoretical calculations showed that molecular structure regulates the electron transfer efficiency from electrode to dye by affecting the electron density and steric hindrance of the azo bond, thereby determining degradation kinetics. This study deepened the influence of the molecular structure on azo dyes bioelectrochemical removal, and provided optimized guidance for the treatment of wastewater containing azo dyes by BESs.
(Copyright © 2026 Elsevier B.V. All rights reserved.)
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Contributed Indexing: Keywords: Azo dyes; Bioelectrochemical systems; Kinetics; Molecular structure; Structure-activity relationship
Substance Nomenclature: 0 (Azo Compounds)
0 (Water Pollutants, Chemical)
0 (Coloring Agents)
Entry Date(s): Date Created: 20260122 Date Completed: 20260701 Latest Revision: 20260701
Update Code: 20260701
DOI: 10.1016/j.bioelechem.2026.109229
PMID: 41570540
Database: MEDLINE
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  Data: Molecular structure-dependent bioelectrochemical decolorization of azo dyes.
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  Data: <searchLink fieldCode="AU" term="%22Yang+HY%22">Yang HY</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China; Pollution Control and Resource Utilization in Industrial Parks Joint Laboratory of Anhui Province, Hefei, China. Electronic address: younghy@ahjzu.edu.cn.<br /><searchLink fieldCode="AU" term="%22Geng+X%22">Geng X</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Quan+ZD%22">Quan ZD</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Yu+L%22">Yu L</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Huang+XH%22">Huang XH</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Li+WH%22">Li WH</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Xue+TZ%22">Xue TZ</searchLink>; Key Laboratory of Water Pollution Control and Wastewater Reuse of Anhui Province, Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse, Anhui Jianzhu University, Hefei, China.<br /><searchLink fieldCode="AU" term="%22Mu+Y%22">Mu Y</searchLink>; State Key Laboratory of Advanced Environmental Technology Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China.
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  Data: <searchLink fieldCode="JN" term="%22100953583%22">Bioelectrochemistry (Amsterdam, Netherlands)</searchLink> [Bioelectrochemistry] 2026 Aug; Vol. 170, pp. 109229. <i>Date of Electronic Publication: </i>2026 Jan 19.
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  Data: <i>Original Publication</i>: [Amsterdam?] : Elsevier, 2000-
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  Data: <searchLink fieldCode="MM" term="%22Azo+Compounds%22">Azo Compounds*</searchLink>/<searchLink fieldCode="MM" term="%22Azo+Compounds+chemistry%22">chemistry</searchLink> <br /><searchLink fieldCode="MM" term="%22Azo+Compounds%22">Azo Compounds*</searchLink>/<searchLink fieldCode="MM" term="%22Azo+Compounds+metabolism%22">metabolism</searchLink> <br /><searchLink fieldCode="MM" term="%22Azo+Compounds%22">Azo Compounds*</searchLink>/<searchLink fieldCode="MM" term="%22Azo+Compounds+isolation+%26+purification%22">isolation & purification</searchLink> <br /><searchLink fieldCode="MM" term="%22Electrochemical+Techniques%22">Electrochemical Techniques*</searchLink>/<searchLink fieldCode="MM" term="%22Electrochemical+Techniques+methods%22">methods</searchLink> <br /><searchLink fieldCode="MM" term="%22Water+Pollutants%2C+Chemical%22">Water Pollutants, Chemical*</searchLink>/<searchLink fieldCode="MM" term="%22Water+Pollutants%2C+Chemical+chemistry%22">chemistry</searchLink> <br /><searchLink fieldCode="MM" term="%22Water+Pollutants%2C+Chemical%22">Water Pollutants, Chemical*</searchLink>/<searchLink fieldCode="MM" term="%22Water+Pollutants%2C+Chemical+isolation+%26+purification%22">isolation & purification</searchLink> <br /><searchLink fieldCode="MM" term="%22Coloring+Agents%22">Coloring Agents*</searchLink>/<searchLink fieldCode="MM" term="%22Coloring+Agents+chemistry%22">chemistry</searchLink><br /><searchLink fieldCode="MH" term="%22Kinetics%22">Kinetics</searchLink> ; <searchLink fieldCode="MH" term="%22Electrodes%22">Electrodes</searchLink> ; <searchLink fieldCode="MH" term="%22Molecular+Structure%22">Molecular Structure</searchLink>
– Name: Abstract
  Label: Abstract
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  Data: Azo dyes, containing one or more azo bonds (-N=N-), are widely used but pose environmental and health risks due to their toxicity and resistance to degradation. Bioelectrochemical systems (BESs) offer a potential approach for their reductive degradation, yet the role of molecular structure in degradation remains unclear. In this study, nine representative azo dyes were examined to access how substituent type and position affect degradation kinetics and electron transfer under controlled cathodic potentials in BESs. Electron-withdrawing substituents (e.g., -SO<subscript>3</subscript><superscript>-</superscript>, -NO<subscript>2</subscript>) and o-/m- substitution enhanced azo bond cleavage, while p-substitution or steric hindered degradation. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed that higher reduction currents and lower charge-transfer resistance correlated with faster degradation. Quantitative structure-activity relationship (QSAR) analysis identified that the -N=N- group and other molecular features such as atom count, are key determinants of azo dyes removal. Experimental and theoretical calculations showed that molecular structure regulates the electron transfer efficiency from electrode to dye by affecting the electron density and steric hindrance of the azo bond, thereby determining degradation kinetics. This study deepened the influence of the molecular structure on azo dyes bioelectrochemical removal, and provided optimized guidance for the treatment of wastewater containing azo dyes by BESs.<br /> (Copyright © 2026 Elsevier B.V. All rights reserved.)
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  Data: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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  Data: <i>Keywords: </i>Azo dyes; Bioelectrochemical systems; Kinetics; Molecular structure; Structure-activity relationship
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