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

At a Glance

Metadata	Details
Publication Date	2025-10-23
Authors	Thomas Moses, Doğan Çirmi, Yalçın Fidan, Belgin Gözmen
Institutions	Mersin Üniversitesi
Analysis	Full AI Review Included

Executive Summary: High-Performance BDD Anodes for Heterogeneous Electro-Fenton (HEF)

This technical analysis focuses on the critical role of Boron-Doped Diamond (BDD) anodes in achieving highly efficient, pH-independent degradation of persistent organic pollutants (POPs) via Heterogeneous Electro-Fenton (HEF) processes.

Superior Anode Performance: The $\text{CF}@\text{Fe}_3\text{O}_4$ cathode paired with a BDD anode consistently outperformed the traditional Pt anode, demonstrating enhanced degradation kinetics and energy efficiency.
High Mineralization Efficiency: The BDD system achieved 100% degradation of clofibric acid (CFA) under mild conditions (50 mA) and maintained high mineralization (>85%) across a wide pH range (pH 3-8).
Mechanism of Action: BDD’s high oxygen evolution overpotential (2.2 V vs. SHE) facilitates the generation of semi-adsorbed hydroxyl radicals ($\text{BDD}(\cdot\text{OH})$), which are crucial for the complete mineralization of recalcitrant intermediate products.
Energy Efficiency: The BDD electrode pair exhibited high Mineralization Current Efficiency (MCE), peaking at 32.74% (3 h, 50 mA), confirming efficient electrical energy utilization compared to homogeneous EF systems.
Environmental Sustainability: The $\text{CF}@\text{Fe}_3\text{O}_4$ cathode demonstrated excellent stability over 5 reuse cycles with no significant performance loss, minimizing secondary pollution from iron leaching.
Application Focus: This research validates BDD as the optimal anode material for Electrochemical Advanced Oxidation Processes (EAOPs) targeting stable pharmaceutical pollutants in wastewater treatment.

Technical Specifications

The following hard data points were extracted, highlighting the performance advantages of the BDD anode in the HEF system.

Parameter	Value	Unit	Context
Anode Material (Optimal)	Boron-Doped Diamond (BDD)	N/A	Used for high mineralization
Cathode Material	$\text{CF}@\text{Fe}_3\text{O}_4$	N/A	Bifunctional catalyst
BDD $\text{O}_2$ Overpotential	2.2	V vs. SHE	Facilitates $\text{BDD}(\cdot\text{OH})$ generation
Pt $\text{O}_2$ Overpotential	1.6	V vs. SHE	Lower radical generation
Optimal Current (Degradation)	50	mA	Achieved 99% CFA degradation in ~20 min (BDD)
Mineralization Current Efficiency (MCE)	32.74	%	Highest MCE achieved (3 h, 50 mA, BDD)
Mineralization (BDD, 100 mA)	>85	%	Achieved after 3 h across pH 3, 6, and 8
$\text{Fe}_3\text{O}_4$ Nanoparticle Size Range	7-17	nm	Observed via FESEM
$\text{Fe}_3\text{O}_4$ Crystallite Size (XRD)	15.3	nm	Determined via Scherrer equation
System Reusability	5	Cycles	No significant performance loss observed

Key Methodologies

The heterogeneous electro-Fenton system relied on the precise synthesis of the cathode and comparative electrochemical testing using high-performance anodes.

Cathode Synthesis: Magnetite ($\text{Fe}_3\text{O}_4$) nanoparticles were loaded onto activated carbon felt (CF) using a solvothermal method to create the bifunctional $\text{CF}@\text{Fe}_3\text{O}_4$ cathode.
Electrode Characterization: The $\text{CF}@\text{Fe}_3\text{O}4$ cathode was characterized using FESEM (morphology), XRD (crystallite size), Cyclic Voltammetry (CV) for Oxygen Reduction Reaction (ORR) activity, and Electrochemical Impedance Spectroscopy (EIS) for charge transfer resistance ($\text{R}{\text{ct}}$).
Electrochemical Setup: Experiments were conducted in an undivided cell using the $\text{CF}@\text{Fe}_3\text{O}_4$ cathode paired against two different anode materials: Platinum (Pt) and Boron-Doped Diamond (BDD).
Operating Parameters: The oxidation of clofibric acid (CFA) was tested under constant currents of 50, 100, and 300 mA.
pH Evaluation: The effect of initial pH was investigated at 100 mA, testing pH levels 3, 6, and 8 to confirm the BDD system’s pH independence.
Reactive Species Determination: Radical scavenging experiments using ethanol (EtOH), tert-butanol (TBA), and p-benzoquinone (pBQ) were performed to confirm the dominance of hydroxyl radicals ($\cdot\text{OH}$) and the contribution of superoxide radicals ($\text{O}_2^{\cdot-}$).

6CCVD Solutions & Capabilities

The research clearly demonstrates that the BDD anode is indispensable for maximizing mineralization efficiency and achieving pH-independent operation in advanced oxidation processes. 6CCVD is uniquely positioned to supply the high-quality, custom BDD materials required to replicate, scale, and advance this research.

Applicable Materials

To replicate or extend the high-efficiency EAOPs demonstrated in this paper, researchers require high-purity, heavily doped diamond electrodes.

6CCVD Material Solution	Specification & Application
Heavy Boron-Doped Diamond (BDD)	Primary Requirement. High-conductivity, polycrystalline BDD plates/wafers optimized for high $\text{O}_2$ evolution overpotential (2.2 V vs. SHE) necessary for generating $\text{BDD}(\cdot\text{OH})$ radicals and achieving high mineralization rates.
Polycrystalline Diamond (PCD) Substrates	Ideal for developing next-generation bifunctional cathodes, offering superior thermal and chemical stability compared to carbon felt. Available up to 125 mm diameter.
Custom SCD/PCD Plates	For use in specialized reference electrodes or counter electrodes where high purity and inertness are critical.

Customization Potential

The transition from lab-scale R&D to pilot or industrial applications requires precise control over electrode geometry and integration. 6CCVD offers full customization capabilities:

Custom Dimensions: We supply BDD plates and wafers up to 125 mm in diameter, allowing for direct scale-up of the HEF reactor cell geometry.
Thickness Control: BDD material thickness can be specified from 0.1 µm up to 500 µm, ensuring optimal doping profiles and mechanical stability for long-term use in corrosive environments.
Surface Finish: We provide polishing services to achieve surface roughness ($\text{Ra}$) < 5 nm on inch-size PCD, crucial for controlling catalyst loading uniformity and maximizing active surface area for electron transfer.
Metalization Services: While BDD was used as an anode, 6CCVD offers in-house metalization (Au, Pt, Ti, W, Cu) for creating robust electrical contacts and mounting points, simplifying electrode integration into complex electrochemical cells.

Engineering Support

6CCVD’s in-house team of PhD material scientists specializes in the electrochemistry of diamond materials. We offer comprehensive engineering support for projects focused on Electrochemical Advanced Oxidation Processes (EAOPs) and persistent organic pollutant (POP) remediation.

Doping Optimization: Consultation on achieving the optimal boron doping concentration for maximizing $\text{BDD}(\cdot\text{OH})$ radical generation and current efficiency in specific wastewater matrices.
Cell Design Consultation: Assistance in selecting appropriate electrode dimensions and configurations (e.g., flow-through vs. batch reactors) to minimize mass transport limitations, as highlighted in the research.
Material Selection: Guidance on selecting the most chemically resistant and conductive diamond grade for long-term, high-current density applications.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

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 3 O 4 nanoparticles onto a carbon felt cathode using solvothermal method. The characterizations of CF@Fe 3 O 4 were performed using FESEM, CV and EIS. The developed CF@Fe 3 O 4 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 3 O 4 electrode accelerated electron transfer, minimizing mass transport limitations, enhancing CFA degradation. The CF@Fe 3 O 4 / 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 • OH as the dominant reactive species, with contributions from O 2 •- and SO 4 •- . Mineralization remained high (>85%) across pH 3-8, due to enhanced oxidation of intermediate products via BDD( • OH) and electron transfer mechanisms, while degradation slowed at higher currents. The CF@Fe 3 O 4 /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 3 O 4 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

Original Source

DOI: https://doi.org/10.21203/rs.3.rs-6965557/v1

References

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