Efficient electrochemical degradation of poly- and perfluoroalkyl substances (PFASs) from the effluents of an industrial wastewater treatment plant

At a Glance

Metadata	Details
Publication Date	2017-04-07
Journal	Chemical Engineering Journal
Authors	Beatriz Gómez-Ruiz, Sonia Gómez-Lavín, Nazely Diban, Virginie Boiteux, Adeline Colin
Institutions	Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail, Universidad de Cantabria
Citations	157
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Efficiency PFAS Degradation via BDD Electro-oxidation

This document analyzes the research paper, “Efficient electrochemical degradation of poly- and perfluoroalkyl substances (PFASs) from the effluents of an industrial wastewater treatment plant,” focusing on the application of Boron Doped Diamond (BDD) electrodes for advanced oxidation processes (AOPs).

Executive Summary

This study validates the critical role of Boron Doped Diamond (BDD) anodes in achieving near-complete mineralization of highly persistent pollutants in real-world industrial effluent.

Exceptional Removal Efficiency: A commercial BDD anode achieved 99.74% removal of total PFASs (Per- and polyfluoroalkyl substances), reducing concentrations from 1652 µg/L to 4.22 µg/L in industrial wastewater effluent.
High Mineralization: The BDD electro-oxidation process resulted in a high Total Organic Carbon (TOC) removal rate of 91.1% ± 0.31%, confirming effective mineralization into CO₂ and fluoride ions (F^-).
Robust Material Performance: The Si/BDD anodic material demonstrated exceptional stability, having been in operation for over 10 years and maintaining degradation efficiency after more than 4000 hours of discontinuous use.
Mechanism Validation: Degradation was primarily driven by the BDD’s capacity to generate highly reactive hydroxyl radicals (HO·), effectively breaking down complex fluorotelomers (6:2 FTAB, 6:2 FTSA) into shorter-chain PFCAs and ultimately mineralizing them.
Kinetic Control: Operating at a high current density (50 mA/cm²) shifted the reaction kinetics to mass transport control, accelerating the degradation rate necessary for complete PFAS elimination.

Technical Specifications

The following hard data points were extracted from the electrochemical treatment of the industrial wastewater effluent (E sample).

Parameter	Value	Unit	Context
Initial Total PFASs Concentration (ΣPFASs)	1652	µg/L	WWTP Effluent (Feed Water)
Final Total PFASs Concentration	4.22	µg/L	After 10 hours of treatment
PFASs Removal Efficiency	99.74	%	Achieved at 50 mA/cm²
Total Organic Carbon (TOC) Removal	91.1 ± 0.31	%	Confirms mineralization
Anode Surface Area	70 (0.0070)	cm² (m²)	BDD electrode size
Applied Current Density (j)	50	mA/cm²	Primary operating condition
Cell Voltage Range	13.9 - 15.3	V	Measured at 50 mA/cm²
Treatment Time for 99.74% Removal	10	hours	Total experiment duration
Energy Consumption (99.74% Removal)	256	kWh/m³	High energy demand noted for complete removal
Defluorination Factor (DF-)	126	%	Indicates degradation of unidentified precursors
Anode Operational Stability	>4000	hours	Proven robustness of Si/BDD material

Key Methodologies

The electrochemical degradation was performed using a laboratory-scale flow-by cell under galvanostatic control.

Anode Material Selection: Boron Doped Diamond (BDD) was selected due to its high stability, low adsorption capacity, and high overpotential for oxygen generation, maximizing hydroxyl radical (HO·) production.
Cell Configuration: An undivided flow-by cell (Diacell 106) was utilized, consisting of two circular parallel electrodes (BDD anode and stainless steel cathode).
Electrode Geometry: The BDD anode had a surface area of 70 cm², with an electrode gap maintained at 5 mm.
Operating Conditions: Experiments were performed under galvanostatic control, primarily at a high current density of 50 mA/cm² to ensure mass transport control kinetics.
Feed Circulation: 2 L of effluent sample was circulated from a jacketed glass tank (maintained at 20 °C) to the electro-oxidation cell at a flowrate of 3 L/min.
Kinetic Analysis: Lower current densities (2, 5, 10 mA/cm²) were tested, showing a shift from zero-order kinetics (current control) at low current to first-order kinetics (mass transport control) at 50 mA/cm².
Analytical Confirmation: PFAS degradation and mineralization were confirmed by high TOC removal, progressive fluoride ion (F^-) release, and UHPLC-MS/MS analysis of 29 targeted PFAS compounds.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced BDD materials required to replicate, scale, and optimize this high-efficiency electrochemical PFAS degradation technology. Our expertise in MPCVD diamond synthesis ensures the delivery of robust, high-performance anodes for demanding industrial applications.

Applicable Materials for Electrochemical AOPs

To replicate or extend this research, 6CCVD recommends the following materials:

Heavy Boron Doped Diamond (BDD) Anodes: Essential for high mineralization efficiency. Our BDD material is optimized for high overpotential and maximum hydroxyl radical generation, directly matching the performance requirements demonstrated in this study (99.74% PFAS removal).
Polycrystalline Diamond (PCD) Substrates: We offer robust PCD substrates up to 10 mm thick, providing the mechanical stability necessary for long-term industrial reactor operation, exceeding the 4000+ hours of stability reported.

Customization Potential

The success of BDD electro-oxidation relies on precise electrode geometry and reliable electrical contact. 6CCVD offers comprehensive customization services to meet specific reactor designs:

Research Requirement	6CCVD Customization Capability	Engineering Advantage
Specific Anode Dimensions (e.g., 70 cm² circular)	Custom Dimensions & Laser Cutting: Plates/wafers available up to 125mm. We provide precise laser cutting to match circular, rectangular, or complex flow-cell geometries.	Ensures exact fit and optimal surface area utilization for flow-by or batch reactors, facilitating direct scale-up.
BDD Film Thickness	SCD/PCD Thickness Control: SCD and PCD films available from 0.1 µm up to 500 µm.	Allows researchers to optimize BDD layer thickness for conductivity, cost efficiency, and long-term stability under high current densities (50 mA/cm²).
Electrical Contact & Integration	Internal Metalization Services: We apply custom metal layers (Au, Pt, Pd, Ti, W, Cu) directly to the BDD surface.	Guarantees low-resistance electrical contacts, crucial for minimizing voltage drop and controlling energy consumption (256 kWh/m³) during high-current operation.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of diamond electrodes for electrochemical applications. We can assist with material selection and optimization for similar PFAS Remediation and Industrial Wastewater Treatment projects, focusing on:

Optimizing boron doping levels for specific current density regimes.
Designing electrode geometries for improved mass transport kinetics.
Selecting appropriate substrate materials (Si, Ta, etc.) for maximum thermal and chemical robustness.

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

Tech Support

Original Source

DOI: https://doi.org/10.1016/j.cej.2017.04.040

References

2009 - Monitoring of perfluorinated compounds in edible fish from the Mediterranean Sea [Crossref]
2005 - Synthesis of environmentally relevant fluorinated surfactants - A review [Crossref]
2006 - Sources, fate and transport of perfluorocarboxylates [Crossref]
2013 - Perfluorinated sulfonate and carboxylate compounds in eggs of seabirds breeding in the Canadian Arctic: temporal trends (1975-2011) and interspecies comparison [Crossref]
2009 - Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in sewage treatment plants [Crossref]
2014 - Treatment of poly- and perfluoroalkyl substances in U.S. full-scale water treatment systems [Crossref]