Degradation of C. I. Direct Red 80 by the Electro-Fenton Process

At a Glance

Metadata	Details
Publication Date	2022-08-10
Journal	KnE Materials Science
Authors	Boaventura Borges, Ana Baía, Ana Lopes, Maria José Pacheco, Lurdes Ciríaco
Institutions	University of Beira Interior
Analysis	Full AI Review Included

Technical Analysis and Documentation: Boron-Doped Diamond for Advanced Oxidation Processes

Executive Summary

This research validates the critical role of Boron-Doped Diamond (BDD) anodes in highly effective electrochemical wastewater treatment, specifically the Electro-Fenton (EF) process for degrading recalcitrant textile dyes (C. I. Direct Red 80, DR80).

Core Application: High-efficiency degradation and mineralization of organic pollutants (DR80) using the Electro-Fenton process.
Material Validation: The BDD anode is confirmed as the superior material, leveraging its high oxygen-overpotential to generate adsorbed hydroxyl radicals (BDD(HO)•).
Performance Metrics: Achieved exceptional pollutant removal rates, including 91% DR80 removal (at 180 C charge), 99% Chemical Oxygen Demand (COD) removal, and 86% Total Organic Carbon (TOC) removal.
Mineralization Advantage: Unlike conventional electrodes, BDD promotes high mineralization degrees (TOC removal), transforming the dye into non-toxic by-products rather than just intermediate compounds.
Operational Parameters: Optimal performance was observed at low pH (3-4) and moderate current densities (e.g., 25 A m^-2) when using soluble iron sources.
6CCVD Value Proposition: 6CCVD specializes in custom, high-conductivity BDD films necessary to replicate and scale this high-performance Advanced Oxidation Process (AOP).

Technical Specifications

The following hard data points were extracted from the experimental setup and results, highlighting the requirements for the BDD anode system:

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	High O₂-overpotential electrode (Neocoat source used)
Cathode Material	Carbon-felt	N/A	Used for H₂O₂ electrogeneration
BDD Anode Immersed Area	20	cm²	Experimental BDD electrode size
Carbon-felt Cathode Area	136	cm²	Experimental cathode size
Initial DR80 Concentration	50	mg L^-1	Target pollutant concentration
Initial Iron Concentration	10	mg L^-1	Required Fenton catalyst concentration
Applied Current Density (j) Range	12.5, 25, 50	A m^-2	Operational variables studied
Maximum DR80 Removal	91	%	Achieved at 12.5 A m^-2 (180 C charge)
Maximum COD Removal	99	%	Achieved with Iron Sulfate at 25 A m^-2
Maximum TOC Removal	86	%	Achieved with Iron Oxide at 12.5 A m^-2
Optimum EF pH Range	3-4	N/A	Required for optimal iron speciation and H₂O₂ decomposition
Total Applied Charge Range	180, 360, 720	C	Total charge applied based on duration and current density

Key Methodologies

The Electro-Fenton experiments utilized a batch-mode electrochemical cell setup optimized for continuous H₂O₂ electrogeneration and high radical production.

Cell Configuration: Undivided, cylindrical glass cell with a useful volume of 200 mL. Continuous magnetic stirring was used to enhance mass transport.
Electrode Placement: The BDD anode (20 cm² immersed area) was centered and surrounded by the carbon-felt cathode (136 cm² immersed area, 0.5 cm thickness).
H₂O₂ Generation: Continuous O₂ saturation was maintained by bubbling compressed air at 1 L min^-1 through a fritted glass diffuser, starting 10 minutes prior to the assay.
Power Supply: A DC power supply (GW, Lab DC, model GPS-3030D) was used to control the anodic current density (j).
Current Density Variation: Experiments were conducted at three anodic current densities: 12.5, 25, and 50 A m^-2.
Charge Control: The duration of the experiments was adjusted to apply consistent electric charges (180 C, 360 C, and 720 C) across the different current densities.
Iron Sources Studied: Iron sulfate, ferric chloride, iron oxide, and the natural mineral chalcopyrite were tested to evaluate catalyst influence.
Analysis: Performance was monitored by measuring DR80 concentration (spectrophotometrically), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Dissolved Iron (TDI), dissolved Fe²⁺, H₂O₂, pH, and conductivity.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-performance Boron-Doped Diamond (BDD) materials required to replicate, optimize, and scale this advanced Electro-Fenton technology for industrial wastewater treatment.

Applicable Materials

To achieve the high O₂-overpotential and robust radical generation demonstrated in this research, 6CCVD recommends the following material specifications:

Heavy Boron-Doped PCD (BDD): Our polycrystalline BDD films are engineered for high conductivity and stability, ensuring maximum efficiency in electrochemical AOPs. This material is essential for generating the adsorbed hydroxyl radicals (BDD(HO)•) that drive high TOC mineralization.
Custom Doping Control: We offer precise control over boron concentration to optimize the trade-off between conductivity and overpotential, critical for maximizing pollutant degradation rates and minimizing energy consumption.

Customization Potential

The success of electrochemical processes relies heavily on precise electrode geometry and integration. 6CCVD offers full customization capabilities far exceeding standard commercial offerings:

Requirement from Research	6CCVD Customization Capability	Benefit to Client
Anode Area (20 cm²)	Custom Plates/Wafers up to 125 mm diameter.	Allows for rapid scale-up from lab-scale (20 cm²) to pilot or industrial reactors.
BDD Film Thickness	SCD/PCD thickness from 0.1 µm up to 500 µm.	Optimization of electrode lifespan and cost efficiency based on application demands.
Electrode Integration	Custom Metalization Services (Au, Pt, Pd, Ti, W, Cu).	Ensures robust, low-resistance electrical contacts for high current density operation (up to 50 A m^-2 and beyond).
Unique Geometries	Precision laser cutting and shaping services.	Fabrication of complex electrode geometries (e.g., flow-through electrodes, specific aspect ratios) for optimized reactor design.
Substrate Options	BDD deposition on various substrates (e.g., Si, Nb, Ta, Ti) for specific mechanical and thermal requirements.	Flexibility in designing durable, high-performance electrochemical cells.

Engineering Support

The results show that optimal performance depends on balancing current density, iron source, and initial pH. 6CCVD’s in-house PhD material science team provides expert consultation to accelerate your research and development:

Material Selection for AOPs: Assistance in selecting the optimal BDD doping level and film morphology for specific Advanced Oxidation Processes (AOPs), including Electro-Fenton and anodic oxidation.
Scale-Up Consultation: Guidance on transitioning from batch-mode (200 mL cell) to continuous flow systems, focusing on electrode sizing and current distribution.
Electrode Lifetime Analysis: Support in designing BDD electrodes for maximum stability and longevity under aggressive acidic (pH 3-4) and high-radical operating conditions.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available) to ensure your research or industrial project receives the highest quality diamond materials promptly.

View Original Abstract

Electro-Fenton process was applied in the degradation of the textile dye C. I. Direct Red 80 (DR80), using a boron-doped diamond anode and a carbon-felt cathode. The influence of the applied current density and of the type of iron source was evaluated. The iron sources studied were iron sulfate, ferric chloride, iron oxide and chalcopyrite, a natural iron-containing mineral. The obtained results showed that the electro-Fenton process is effective in the DR80 degradation and in the pollutant load elimination. Higher treatment efficiencies were attained when using iron sulfate as iron source. Still, the results obtained with the natural mineral chalcopyrite were quite promising. Although DR80 removal was more efficient at lower applied current densities, the same was not observed for the chemical oxygen demand removal, indicating that, at lower applied current densities, the dye is not completely mineralized, but rather transformed into other by-products. Keywords: C. I. Direct Red 80; Advanced oxidation processes; Electro-Fenton, Borondoped diamond anode, Carbon-felt cathode.

Tech Support

Original Source

DOI: https://doi.org/10.18502/kms.v7i1.11612