Methiocarb Degradation by Electro-Fenton - Ecotoxicological Evaluation

At a Glance

Metadata	Details
Publication Date	2020-12-12
Journal	Molecules
Authors	Faléstine Souiad, Ana Sofia Rodrigues, Ana Lopes, Lurdes Ciríaco, Maria José Pacheco
Institutions	University of Beira Interior, Université Constantine 2
Citations	11
Analysis	Full AI Review Included

Technical Documentation & Analysis: BDD for Advanced Electro-Fenton Processes

Executive Summary

This research validates the critical role of Boron-Doped Diamond (BDD) anodes in highly efficient electrochemical advanced oxidation processes (AOPs) for environmental remediation.

Core Achievement: Successful degradation of Methiocarb, a highly hazardous carbamate pesticide, using the Electro-Fenton (EF) process.
Material Validation: The BDD anode was essential, leveraging its high oxygen-overpotential to generate adsorbed hydroxyl radicals (BDD(*OH)), significantly enhancing organic matter oxidation.
High Efficiency: Total Methiocarb removal (>99%) was achieved rapidly at a low applied electric charge of 90 C.
Toxicity Reduction: The EF treatment resulted in a remarkable 450x average reduction in acute toxicity towards the model organism Daphnia magna, moving the solution from “Highly Toxic” (~900 TU) to “Toxic” (~2 TU).
Optimization Insight: Highest mineralization (TOC removal >90%) was achieved at the lowest tested current density (12.5 A m^-2), confirming that surface-mediated oxidation by BDD(*OH) is highly effective for complete mineralization.
6CCVD Value Proposition: 6CCVD specializes in manufacturing custom, high-quality BDD anodes up to 125mm in diameter, providing the necessary scale and precision for industrializing this highly effective wastewater treatment technology.

Technical Specifications

The following data points highlight the performance metrics achieved using the BDD anode in the Electro-Fenton system:

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	High O₂-overpotential anode
Anode Immersed Area	20	cm²	Used in batch reactor setup
Initial Methiocarb Concentration	19.8 ± 0.5 to 20.3 ± 0.5	mg L^-1	Aqueous solution
Initial Acute Toxicity (TU)	883.1 to 929.4	TU	Highly Toxic classification
Final Acute Toxicity (TU)	~1.96 to ~2.02	TU	Achieved after 720 C charge
Toxicity Reduction Factor	450x (average)	N/A	Reduction towards Daphnia magna
Total MC Removal	>99	%	Achieved at 40 minutes or 120 C charge
Highest TOC Removal	>90	%	Achieved at 720 C, 10 mg L^-1 Fe, 12.5 A m^-2
Applied Anodic Current Density ($j$)	12.5, 25, 50	A m^-2	Experimental variables
Optimum Initial pH	~3.0	N/A	Required for optimal EF process
Cathode Material	Carbon Felt	N/A	Used for H₂O₂ electrogeneration

Key Methodologies

The Electro-Fenton experiments relied on precise control of electrochemical parameters and material selection:

Electrode Configuration: An undivided, cylindrical glass cell (200 mL volume) was used. The BDD anode (20 cm² immersed area) was centered and surrounded by a carbon-felt cathode (130 cm² immersed area, 0.5 cm thickness).
Iron Source: Iron(III) sulfate pentahydrate or ferric chloride hexahydrate was used as the iron source, tested at concentrations of 10 mg L^-1 and 30 mg L^-1 Fe.
Oxygen Supply: Continuous O₂ saturation was ensured by bubbling compressed air (1 L min^-1) through a fritted glass diffuser, starting 10 minutes before the assay to facilitate in situ H₂O₂ electrogeneration.
Current Control: A DC power supply maintained constant anodic current densities ($j$) at 12.5, 25, and 50 A m^-2.
Reaction Monitoring: Samples were collected every 10 minutes for Methiocarb concentration determination (HPLC) and analyzed for Total Organic Carbon (TOC), dissolved Fe²⁺, H₂O₂, and acute ecotoxicity (EC₅₀/TU) towards Daphnia magna.

6CCVD Solutions & Capabilities

The successful application of BDD in this high-performance Electro-Fenton system directly aligns with 6CCVD’s core expertise in MPCVD diamond manufacturing. 6CCVD provides the necessary high-quality, custom BDD materials required to replicate this research and scale it for industrial wastewater treatment applications.

Research Requirement	6CCVD Solution & Advantage	Technical Specification
BDD Anode Material	Heavy Boron-Doped Diamond (BDD) Material	6CCVD supplies highly conductive BDD (SCD or PCD) optimized for high O₂-overpotential, maximizing the generation of BDD(*OH) radicals essential for complete mineralization.
Electrode Area (20 cm²)	Large-Scale Custom Dimensions for Industrialization	We offer BDD plates/wafers up to 125mm (PCD) and custom laser-cut shapes, enabling seamless scale-up from laboratory (20 cm²) to high-throughput flow reactors.
BDD Layer Thickness	Precision Thickness Control for Lifetime	BDD layer thickness available from 0.1 µm up to 500 µm, allowing engineers to optimize for conductivity, mechanical stability, and extended operational lifetime in aggressive EF environments.
Electrical Contacting	Integrated Metalization Services	6CCVD provides in-house metalization (Au, Pt, Ti, W, Cu) to ensure robust, low-resistance electrical contacts, critical for maintaining high current densities (up to 50 A m^-2) without degradation.
Polishing Requirements	Surface Finish Optimization	While not explicitly required here, 6CCVD offers polishing down to Ra < 5nm (Inch-size PCD), ensuring optimal surface uniformity and performance consistency across large-area electrodes.
Global Supply Chain	Reliable Global Shipping	Global shipping is available (DDU default, DDP available), ensuring prompt delivery of custom BDD electrodes worldwide for time-sensitive research and development projects.

Applicable Materials

To replicate or extend this research in Advanced Oxidation Processes (AOPs), 6CCVD recommends the following materials:

Heavy Boron-Doped Diamond (BDD) Polycrystalline (PCD) material: Ideal for large-area electrodes (up to 125mm) where high conductivity and robust mechanical properties are required for industrial wastewater treatment.
BDD Single Crystal Diamond (SCD) material: Recommended for high-precision micro-electrochemical sensors or specialized research requiring ultra-high purity and specific crystallographic orientation.

Customization Potential

The research utilized a 20 cm² BDD anode. 6CCVD can provide BDD plates significantly larger than this, up to 125mm in diameter, or custom-cut shapes to fit proprietary reactor geometries (e.g., flow cells, stacked plate reactors). Our internal metalization capabilities ensure that the electrodes are delivered ready for integration into high-power electrochemical systems.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science and electrochemical performance of diamond electrodes. We can assist engineers and scientists with material selection, doping level optimization, and substrate design for similar Electro-Fenton and Anodic Oxidation (AO) projects targeting emerging contaminants and recalcitrant organic pollutants.

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

View Original Abstract

This paper studies the degradation of methiocarb, a highly hazardous pesticide found in waters and wastewaters, through an electro-Fenton process, using a boron-doped diamond anode and a carbon felt cathode; and evaluates its potential to reduce toxicity towards the model organism Daphnia magna. The influence of applied current density and type and concentration of added iron source, Fe2(SO4)3·5H2O or FeCl3·6H2O, is assessed in the degradation experiments of methiocarb aqueous solutions. The experimental results show that electro-Fenton can be successfully used to degrade methiocarb and to reduce its high toxicity towards D. magna. Total methiocarb removal is achieved at the applied electric charge of 90 C, and a 450× reduction in the acute toxicity towards D. magna, on average, from approximately 900 toxic units to 2 toxic units, is observed at the end of the experiments. No significant differences are found between the two iron sources studied. At the lowest applied anodic current density, 12.5 A m−2, an increase in iron concentration led to lower methiocarb removal rates, but the opposite is found at the highest applied current densities. The highest organic carbon removal is obtained at the lowest applied current density and added iron concentration.

Tech Support

Original Source

DOI: https://doi.org/10.3390/molecules25245893

References

2017 - Investigation of the presence and endocrine activities of pesticides found in wastewater effluent using yeast-based bioassays [Crossref]
2016 - Effect of Fe2+ on the degradation of the pesticide profenofos by electrogenerated H2O2 [Crossref]
2014 - Electrochemically assisted remediation of pesticides in soils and water: A review [Crossref]
2018 - Electrochemical oxidation of organic pollutants for wastewater treatment [Crossref]
2017 - Electrochemical advanced oxidation processes: A review on their application to synthetic and real wastewaters [Crossref]
2013 - Removal of residual anti-inflammatory and analgesic pharmaceuticals from aqueous systems by electrochemical advanced oxidation processes. A review [Crossref]
2017 - Anodic oxidation of the insecticide imidacloprid on mixed metal oxide (RuO2-TiO2 and IrO2-RuO2-TiO2) anodes [Crossref]