Electrochemical Oxidation of Selected Micropollutants from Environment Matrices Using Boron-Doped Diamond Electrodes - Process Efficiency and Transformation Product Detection

At a Glance

Metadata	Details
Publication Date	2024-12-11
Journal	Water
Authors	Filip Gamoń, S. Żabczyński, Małgorzata Szopińska, Mattia Pierpaoli, Dawid Zych
Institutions	Gdańsk University of Technology, Silesian University of Technology
Analysis	Full AI Review Included

Technical Documentation & Analysis: Electrochemical Oxidation using 6CCVD BDD Electrodes

Executive Summary

This research validates the superior performance of Boron-Doped Diamond (BDD) anodes, fabricated via Microwave Plasma-Assisted Chemical Vapour Deposition (MWPECVD), for advanced electrochemical oxidation (EO) of persistent micropollutants.

Exceptional Removal Efficiency: The EO-BDD process achieved removal efficiencies exceeding 99% for Bisphenol A (BPA) and >96% for Diclofenac (DCF) in complex, real-world matrices, including Landfill Leachate (LL) and Treated Wastewater (TWW-D).
Material Validation: The study confirms that BDD electrodes, due to their non-polar nature and broad oxygen overpotential window, exhibit exceptional resistance to fouling and enable the generation of powerful oxidizing species (hydroxyl and sulfate radicals).
Custom Doping Impact: Two distinct boron doping levels (0.5 k and 10 k) were tested, demonstrating that while both achieved high removal rates, precise doping control is critical for optimizing performance in specific matrices.
Broad Application Scope: Beyond micropollutants, the EO-BDD process effectively removed Chemical Oxygen Demand (COD) (up to 94.24%) and Ammonium Nitrogen (N-NH₄⁺) (up to 78.25%) from LL, positioning BDD as a viable technology for quaternary wastewater treatment.
Fabrication Match: The electrodes were fabricated on 50-mm Niobium substrates using MWPECVD—a core capability offered by 6CCVD for custom BDD anode production.
Regulatory Compliance: The findings support the adoption of EO-BDD technology to meet stringent new EU Directive requirements for micropollutant removal in municipal and industrial wastewater.

Technical Specifications

The following hard data points were extracted from the experimental setup and results, highlighting the critical parameters for BDD fabrication and electrochemical performance.

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	N/A	MWPECVD on Niobium substrate
Substrate Diameter	50	mm	Niobium
Low Boron Doping Level (0.5 k)	~1.5 x 10¹⁷	at/cm³	Used for comparison of efficiency
High Boron Doping Level (10 k)	3 x 10²¹	at/cm³	Used for comparison of efficiency
Anode Geometric Area	10.5	cm²	Used in 400-mL undivided electrolytic cell
Anode-Cathode Distance	2.5	cm	Maintained during EO tests
Current Density (LL)	120	mA/cm²	Optimized for Landfill Leachate matrix
Current Density (TWW)	25	mA/cm²	Optimized for Treated Wastewater matrices
Maximum BPA Removal (LL)	>99.85	%	Achieved after 4 h treatment
Maximum DCF Removal (LL)	>99.23	%	Achieved after 4 h treatment
Maximum COD Removal (LL)	94.24	%	Achieved after 8 h treatment (10 k BDD)
Maximum N-NH₄⁺ Removal (LL)	78.25	%	Achieved after 8 h treatment (10 k BDD)
Initial LL Chloride Concentration	2690 ± 70	mg/L	High salinity matrix, facilitating indirect EO

Key Methodologies

The BDD electrodes were fabricated using highly controlled MPCVD processes, which are standard capabilities at 6CCVD.

Substrate Preparation: 50-mm diameter Niobium substrates were prepared via sandblasting, followed by cleaning in acetone and isopropanol in an ultrasonic bath.
Seeding: Substrates were seeded using a water-based diamond slurry via sonication to ensure high nucleation density.
Deposition Method: Microwave Plasma-Assisted Chemical Vapour Deposition (MWPECVD) was utilized for diamond film growth.
Microwave Power: Maintained at 1300 W.
Total Pressure: Maintained at 50 Torr.
Substrate Temperature: Set to 700 °C to control crystal quality and doping incorporation.
Gas Mixture: H₂, CH₄, and B₂H₆ were used, with B₂H₆ flow rates precisely adjusted to achieve the two target boron doping levels (0.5 k and 10 k).
Electrochemical Testing: Experiments were conducted under galvanostatic conditions in a custom 400-mL undivided electrolytic cell, using the BDD film as the anode and stainless-steel mesh as the cathode.

6CCVD Solutions & Capabilities

This research demonstrates the critical role of high-quality, custom-engineered BDD electrodes in advanced water treatment. 6CCVD is uniquely positioned to supply the materials and customization required to replicate, scale, and extend this research.

Research Requirement	6CCVD Solution & Capability	Technical Advantage & Sales Driver
Material Specification	Heavy Boron Doped PCD (Polycrystalline Diamond)	Our MPCVD BDD films provide the necessary metallic conductivity and chemical stability for high-efficiency EO, ensuring long electrode lifetime and superior performance compared to conventional anodes (e.g., Ti/Pt).
Custom Doping Levels	Precision BDD Doping Control	6CCVD offers precise control over boron incorporation, allowing researchers to specify doping levels from 10¹⁷ at/cm³ (0.5 k equivalent) up to 10²¹ at/cm³ (10 k equivalent) to optimize radical generation and current efficiency for specific matrices (e.g., high-salinity LL vs. low-COD TWW).
Substrate Compatibility	BDD on Refractory Metals (Nb, Ta, W)	The paper utilized 50-mm Niobium substrates. 6CCVD routinely deposits BDD films on Niobium, Tantalum, and Tungsten, providing robust, conductive, and chemically inert electrode foundations suitable for industrial scaling.
Scaling Requirements	Large Area PCD Plates	While the study used 50-mm wafers, 6CCVD can supply custom PCD plates up to 125mm in diameter, facilitating the transition from lab-scale research to pilot-scale electrochemical reactors.
Electrode Geometry	Custom Dimensions and Laser Cutting	We offer custom fabrication services, including precise laser cutting, to meet exact geometric specifications (e.g., 10.5 cm² anode area) required for specific electrolytic cell designs.
Thickness Control	BDD Film Thickness (0.1 µm - 500 µm)	6CCVD guarantees precise control over BDD film thickness, ensuring optimal electrochemical performance and cost efficiency for both thin-film anodes and thick, self-supporting structures.
Engineering Support	In-House PhD Team Consultation	6CCVD’s expert material scientists can assist researchers in selecting the optimal BDD material (doping, thickness, substrate) for advanced oxidation processes (AOPs), micropollutant degradation, and electrochemical sensing projects.

For custom specifications or material consultation regarding BDD anodes for advanced oxidation processes, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Bisphenol A (BPA) and diclofenac (DCF) are among the most prevalent micropollutants in aquatic environments, with concentrations reaching up to several hundred µg/L. These compounds pose significant risks to biodiversity and environmental health, necessitating the development of effective removal methods. However, both BPA and DCF can be resistant to conventional treatment technologies, highlighting the need for innovative approaches. Electrochemical oxidation (EO) has emerged as a promising solution. In this study, we assessed the effectiveness of EO using boron-doped diamond (BDD) anodes to remove BPA and DCF from two types of treated wastewater (TWW-W and TWW-D) and landfill leachate (LL). The evaluation included an analysis of the removal efficiency of BPA and DCF and the identification of transformation products generated during the process. Additionally, the feasibility of the EO-BDD process to remove ammonium nitrogen (N-NH4+) and organic compounds present in these environmental matrices was investigated. The EO-BDD treatment achieved remarkable removal efficiencies, reducing BPA and DCF concentrations by over 96% in LL and TWW-W. Transformation product analyses identified four intermediates formed from parent compounds during the oxidation process. Furthermore, the EO-BDD process effectively removed both chemical oxygen demand (COD) and ammonium nitrogen from LL, although weaker results were observed for TWWs. These findings underscore the potential of the EO-BDD process as an effective method for the removal of BPA and DCF from challenging matrices, such as wastewater containing micropollutants. It also shows promise as a complementary technology for enhancing current conventional wastewater treatment methods, especially biological degradation.

Tech Support

Original Source

DOI: https://doi.org/10.3390/w16243567

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