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6CCVD Research

Heterogeneous electro-Fenton treatment of clofibric acid with an Fe₃O₄-loaded bifunctional carbon felt cathode via different anode types

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2025-10-23
AuthorsThomas Moses, Doğan Çirmi, Yalçın Fidan, Belgin Gözmen
InstitutionsMersin Üniversitesi
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This study details the development and application of a novel Fe3O4-loaded bifunctional carbon felt (CF@Fe3O4) cathode for the heterogeneous electro-Fenton (HEF) degradation of clofibric acid (CFA), a persistent organic pollutant (POP).

  • Core Innovation: Synthesis of a bifunctional CF@Fe3O4 cathode via solvothermal method, enabling both H2O2 generation and Fe3+/Fe2+ activation directly on the cathode surface.
  • Performance Superiority: The CF@Fe3O4/BDD (Boron-Doped Diamond) anode pair consistently outperformed the CF@Fe3O4/Pt pair and conventional homogeneous EF processes in terms of degradation kinetics and energy efficiency.
  • High Degradation & Mineralization: Achieved 100% CFA degradation under mild conditions (50 mA) and high total organic carbon (TOC) removal, reaching up to 99.21% mineralization after 5 hours at 300 mA (BDD anode).
  • pH Independence: The HEF process using the BDD anode maintained high mineralization efficiency (>85%) across a wide pH range (pH 3-8), overcoming the typical pH limitation of homogeneous Fenton chemistry.
  • Mechanism: Hydroxyl radicals (OH) were identified as the dominant oxidant, with significant contributions from heterogeneous BDD(OH) radicals and superoxide radicals (O2-).
  • Sustainability: The process is environmentally friendly, requiring low Fe3O4 loading, exhibiting negligible Fe ion leaching (avoiding secondary pollution), and demonstrating excellent cathode reusability (stable performance after 5 cycles).

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Catalyst MaterialFe3O4 NPs on Carbon Felt-Bifunctional cathode
Fe3O4 Crystallite Size (D)15.3nmDetermined by XRD analysis
Fe3O4 NP Size Range (SEM)7-17nmObserved on CF surface
Target PollutantClofibric Acid (CFA)-Initial concentration: 0.23 mM
Optimal Current Density (Degradation)50mACF@Fe3O4/BDD pair
CFA Degradation Time (99%)~20minCF@Fe3O4/BDD at 50 mA
Maximum Mineralization (TOC Removal)99.21%CF@Fe3O4/BDD after 5 h at 300 mA
Mineralization Current Efficiency (MCE)32.74%CF@Fe3O4/BDD after 3 h at 50 mA
MCE (Homogeneous EF)27.2%CF/Pt after 3 h at 50 mA
Mineralization Range (pH 3-8)>85%CF@Fe3O4/BDD after 3 h at 100 mA
Pt Anode O2 Evolution Overpotential1.6V vs. SHELow overpotential
BDD Anode O2 Evolution Overpotential2.2V vs. SHEHigh overpotential, facilitates BDD(OH)
Cathode Reusability5cyclesNo significant performance loss observed
CFA pKa Value3.18-Influences ionization state and degradation rate

Key Methodologies

Section titled “Key Methodologies”
  1. Cathode Synthesis (Solvothermal Method): Magnetite (Fe3O4) nanoparticles were loaded onto activated carbon felt (CF) to create the CF@Fe3O4 bifunctional cathode.
  2. Material Characterization:
    • Morphology: Field Emission Scanning Electron Microscopy (FESEM) was used to confirm NP distribution and size (7-17 nm).
    • Crystallography: X-ray Diffraction (XRD) confirmed the cubic spinel structure of Fe3O4 and determined the crystallite size (15.3 nm).
    • Electrochemical Activity: Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were performed under N2 and O2 saturation to evaluate Oxygen Reduction Reaction (ORR) kinetics and charge transfer resistance (Rct).
  3. Electro-Fenton Treatment: Experiments were conducted in an undivided cell using constant applied currents (50, 100, and 300 mA).
  4. Anode Comparison: The CF@Fe3O4 cathode was tested against two different anode materials: Platinum (Pt) and Boron-Doped Diamond (BDD).
  5. Optimization Studies: CFA degradation and mineralization were assessed as a function of:
    • Applied current (50-300 mA).
    • Initial pH (3, 6, and 8).
  6. Reactive Species Determination: Radical scavenging experiments utilized ethanol (EtOH), tert-butanol (TBA), and p-benzoquinone (pBQ) to quantify the contribution of OH, SO4-, and O2- radicals to CFA degradation.
  7. Reusability Testing: The stability and performance retention of the CF@Fe3O4/BDD system were evaluated over five consecutive reuse cycles.

Commercial Applications

Section titled “Commercial Applications”

The technology developed—a highly efficient, pH-independent heterogeneous electro-Fenton system utilizing a magnetic carbon felt cathode and a BDD anode—is highly relevant for advanced water treatment sectors.

  • Pharmaceutical Wastewater Treatment: Direct application for the removal and mineralization of persistent pharmaceutical pollutants (POPs) like clofibric acid (CFA) and other chemically stable organic contaminants.
  • Industrial Effluent Detoxification: Suitable for treating complex industrial wastewaters containing low biodegradable organic compounds, offering a high TOC removal rate.
  • Advanced Oxidation Process (AOP) Systems: Integration into existing or new electrochemical reactor designs, leveraging the high efficiency and wide operating pH range enabled by the BDD anode and bifunctional cathode.
  • Catalyst Manufacturing: Production of magnetic, reusable, and high-conductivity carbon-based composite catalysts (CF@Fe3O4) for environmental remediation technologies.
  • Water Reclamation and Reuse: Provides a non-secondary polluting method (low Fe leaching) for treating water sources destined for environmental discharge or industrial reuse.
View Original Abstract

<title>Abstract</title> Pharmaceutical pollutants like clofibric acid (CFA) pose significant threats to aquatic ecosystems and human health. In this study, a bifunctional cathode was synthesized by loading Fe <sub>3</sub> O <sub>4</sub> nanoparticles onto a carbon felt cathode using solvothermal method. The characterizations of CF@Fe <sub>3</sub> O <sub>4</sub> were performed using FESEM, CV and EIS. The developed CF@Fe <sub>3</sub> O <sub>4</sub> cathode was then evaluated in heterogeneous electro-Fenton (HEF) application in clofibric acid (CFA) oxidation at different current and pH values using Pt and BDD anodes. The CF@Fe <sub>3</sub> O <sub>4</sub> electrode accelerated electron transfer, minimizing mass transport limitations, enhancing CFA degradation. The CF@Fe <sub>3</sub> O <sub>4</sub> / Pt electrode pair exhibited 75% mineralization following 3 h of HEF treatment, whereas the BDD anode exhibited 78% mineralization at 50 mA. Both values outperformed the homogenous EF process with CF in terms of effectiveness. Radical scavenging experiments proved <sup>•</sup> OH as the dominant reactive species, with contributions from O <sub>2</sub> <sup>•-</sup> and SO <sub>4</sub> <sup>•-</sup> . Mineralization remained high (&gt;85%) across pH 3-8, due to enhanced oxidation of intermediate products via BDD( <sup>•</sup> OH) and electron transfer mechanisms, while degradation slowed at higher currents. The CF@Fe <sub>3</sub> O <sub>4</sub> /BDD combination consistently outperformed Pt in terms of both degradation kinetics and energy efficiency. Here we show that even after 5 reuses, the CF@Fe <sub>3</sub> O <sub>4</sub> cathode/BDD anode pair can effectively remove persistent organic pollutants without pH limitation and with an environmentally friendly process without any significant performance loss.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2004 - Endocrine disrupting compounds and other emerging contaminants in the environment: A survey on new monitoring strategies and occurrence data [Crossref]
  2. 2006 - Preliminary risk assessment of the lipid-regulating pharmaceutical clofibric acid, for three estuarine species [Crossref]
  3. 2012 - Identification and ecotoxicity assessment of intermediates generated during the degradation of clofibric acid by advanced oxidation processes [Crossref]
  4. 2023 - Recent advances in application of heterogeneous electro-Fenton catalysts for degrading organic contaminants in water [Crossref]
  5. 2021 - Fe(II)Fe(III) layered double hydroxide modified carbon felt cathode for removal of ciprofloxacin in electro-Fenton process [Crossref]
  6. 2023 - Heterogeneous electro-Fenton treatment of chemotherapeutic drug busulfan using magnetic nanocomposites as catalyst [Crossref]
  7. 2023 - Critical review on the mechanisms of Fe2+ regeneration in the electro-Fenton process: Fundamentals and boosting strategies [Crossref]
  8. 2024 - Highly efficient FeS/Fe3O4@biomass carbon bifunctional catalyst with enriched oxygen vacancies for heterogeneous electro-Fenton catalysis [Crossref]
  9. 2006 - Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes [Crossref]

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