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6CCVD Research

Sustainable Electrochemical Activation of Self-Generated Persulfate for the Degradation of Endocrine Disruptors - Kinetics, Performances, and Mechanisms

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2024-02-17
JournalToxics
AuthorsXiaofeng Tang, Zhiquan Jin, Rui Zou, Yi Zhu, Xia Yao
InstitutionsChinese Academy for Environmental Planning, Zhejiang University of Technology
Citations3
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This study introduces a novel, sustainable electrochemical system utilizing a Boron-Doped Diamond (BDD) anode and an Activated Carbon Fiber (ACF) cathode for the degradation of endocrine disruptors (Bisphenol A, BPA).

  • Self-Circulation Mechanism: The system achieves a self-circulation process of sulfate (SO42-) and persulfate (S2O82-) ions, eliminating the need for external chemical persulfate addition, aligning with sustainable chemistry principles.
  • Superior Performance: The undivided BDD/ACF system achieved 98.6% BPA removal in 60 minutes, significantly outperforming control systems like Pt/ACF (86.3%) and BDD/Pt (79.3%).
  • Synergistic Activation: High efficiency is attributed to the synergistic effect: the BDD anode generates S2O82-, while the ACF cathode activates S2O82- (and generates H2O2) to produce potent SO4•- and •OH radicals.
  • Kinetic Advantage: The pseudo-first-order rate constant (Kapp) for BDD/ACF (0.072 min-1) was substantially higher than other tested configurations.
  • Cost Efficiency: Optimized operation resulted in a low overall treatment cost estimated at 1.454 USD/m3, demonstrating economic viability.
  • Broad Applicability: The system maintained high degradation efficiency even in complex matrices (92.0% removal in tap water and 73.6% in surface water).

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Anode MaterialBoron-Doped Diamond (BDD)N/A800 ppm Boron, 1 mm coating thickness
Cathode MaterialActivated Carbon Fiber (ACF)N/A25 mm x 50 mm x 1 mm dimensions
Optimized Current Density15mA/cm2Selected for high current efficiency
Optimized Initial pH2.0N/AHighest BPA degradation efficiency (98.6%)
Initial BPA Concentration0.044mMModel pollutant concentration
Electrolyte Concentration50mMNa2SO4 (Sulfate initiator)
BPA Removal Efficiency98.6%Undivided BDD + ACF system (60 min)
Pseudo-First-Order Rate Constant (Kapp)0.072min-1BDD + ACF system
Divided Cell Voltage (Average)25.8VOperated at 15 mA/cm2
Undivided Cell Voltage (Average)7.2VOperated at 15 mA/cm2
Energy Consumption (EC)0.29USD/m3Operational energy cost component
Total Treatment Cost1.454USD/m3Including amortization and operation
S2O82- Accumulation (BDD/ACF)1.11mMSingle-chamber system (60 min)
H2O2 Accumulation (BDD/ACF)0.09mMSingle-chamber system (60 min)
Mineralization Efficiency (TOC removal)31.7%Undivided BDD/ACF system (60 min)

Key Methodologies

Section titled “Key Methodologies”
  1. Electrolysis Setup: Experiments were conducted in 250 mL solution volumes using either a single-chamber (undivided) reactor or a divided cell separated by a Nafion-117 Cation Exchange Membrane (CEM).
  2. Electrode Configuration: BDD served as the anode and ACF served as the cathode, with a 2 cm electrode distance. Platinum (Pt) electrodes were used for comparative control experiments.
  3. Electrolyte and pH Control: 50 mM Na2SO4 was used as the supporting electrolyte. Initial pH was optimized at 2.0 using H2SO4 or NaOH (0.1 M).
  4. Optimization: Current density was optimized between 0 and 25 mA/cm2, selecting 15 mA/cm2 for optimal efficiency and energy consumption.
  5. Radical Identification (Quenching): Methanol (highly reactive with both •OH and SO4•-) and tert-butanol (TBA, highly selective for •OH) were used as radical scavengers (500 mM) to distinguish the contributions of the reactive species.
  6. Radical Confirmation (EPR): Electron Paramagnetic Resonance (EPR) spectroscopy, using DMPO as a capture agent, confirmed the presence of DMPO-SO4•- and DMPO-•OH adducts, particularly at the cathode surface in the undivided cell.
  7. Intermediate Quantification: S2O82- concentration was determined using the ABTS colorimetric method. H2O2 concentration was determined using the potassium titanium (IV) oxalate method.
  8. Degradation Pathway Analysis: Liquid Chromatography-Mass Spectrometry (LC-MS) was employed to identify degradation intermediates (e.g., mono- and multihydroxylation products, quinone compounds, hydroxybenzoic acid).
  9. Toxicity Assessment: The ecological structure activity relationship (ECOSAR) program was used to predict the acute and chronic toxicity of BPA and its intermediates to aquatic organisms (fish, daphnid, green algae).

Commercial Applications

Section titled “Commercial Applications”
  • Wastewater Treatment (EDCs/POPs): Highly effective for the mineralization and degradation of persistent organic pollutants (POPs) and endocrine-disrupting compounds (EDCs) in industrial and municipal wastewater streams.
  • Pretreatment Systems: Suitable for use as a cost-effective pretreatment step for complex influent waters (e.g., landfill leachate, reverse osmosis concentrate) prior to biological treatment, enhancing overall system efficiency.
  • Sustainable Water Remediation: Directly applicable in systems requiring reduced chemical usage, leveraging the BDD/ACF self-circulation mechanism to minimize reagent costs and residue generation.
  • Electrode Technology: Drives demand for high-stability, high-overpotential BDD anodes and specialized ACF cathodes optimized for electrochemical activation of persulfate and H2O2 generation.
  • Advanced Oxidation Process (AOP) Integration: Offers an energy-efficient alternative to conventional AOPs (like traditional Fenton or UV/Persulfate systems) by internally generating and activating the oxidant species.
View Original Abstract

This study presents an electrolysis system utilizing a novel self-circulation process of sulfate (SO42−) and persulfate (S2O82−) ions based on a boron-doped diamond (BDD) anode and an activated carbon fiber (ACF) cathode, which is designed to enable electrochemical remediation of environmental contaminants with reduced use of chemical reagents and minimized residues. The production of S2O82− and hydrogen peroxide (H2O2) on the BDD anode and ACF cathode, respectively, is identified as the source of active radicals for the contaminant degradation. The initiator, sulfate, is identified by comparing the degradation efficiency in NaSO4 and NaNO3 electrolytes. Quenching experiments and electron paramagnetic resonance (EPR) spectroscopy confirmed that the SO4−· and ·OH generated on the ACF cathode are the main reactive radicals. A comparison of the degradation efficiency and the generated S2O82−/H2O2 of the divided/undivided electrolysis system is used to demonstrate the superiority of the synergistic effect between the BDD anode and ACF cathode. This work provides evidence of the effectiveness of the philosophy of “catalysis in lieu of supplementary chemical agents” and sheds light on the mechanism of the generation and transmission of reactive species in the BDD and ACF electrolysis system, thereby offering new perspectives for the design and optimization of electrolysis systems.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2020 - Persistent free radicals on N-doped hydrochar for degradation of endocrine disrupting compounds [Crossref]
  2. 2023 - A critical review of environmental remediation via iron-mediated sulfite advanced oxidation processes [Crossref]
  3. 2022 - High-efficiency electrochemical degradation of phenol in aqueous solutions using Ni-PPy and Cu-PPy composite materials [Crossref]
  4. 2022 - Single-atom Fe catalysts for fenton-like reactions: Roles of different N species [Crossref]
  5. 2022 - Functional carbon nitride materials in photo-fenton-like catalysis for environmental remediation [Crossref]
  6. 2019 - Size tunable Bi3O4Br hierarchical hollow spheres assembled with {0 0 1}-facets exposed nanosheets for robust photocatalysis against phenolic pollutants [Crossref]
  7. 2022 - Advanced catalytic ozonation for degradation of pharmaceutical pollutants-A review [Crossref]
  8. 2016 - Routes for the electrochemical degradation of the artificial food azo-colour Ponceau 4R by advanced oxidation processes [Crossref]
  9. 2014 - Electrochemical degradation of sulfonamides at BDD electrode: Kinetics, reaction pathway and eco-toxicity evaluation [Crossref]
  10. 2006 - Photochemically-assisted electrochemical degradation of landfill leachate [Crossref]

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