Degradation of gestodene (GES)–17α-ethinylestradiol (EE2) mixture by electrochemical oxidation

At a Glance

Metadata	Details
Publication Date	2016-10-01
Journal	Journal of Water and Health
Authors	Hugo Alejandro Nájera-Aguilar, Rubén Fernando Gutiérrez-Hernández, Rocío González de los Santos, Carlos Manuel García-Lara, Roger I. Méndez‐Novelo
Institutions	Universidad de Ciencias y Artes de Chiapas, Autonomous University of Yucatán
Citations	8
Analysis	Full AI Review Included

Technical Analysis and Commercialization Strategy: BDD Electrodes for Advanced Electrochemical Oxidation (GES-EE2 Degradation)

Executive Summary

This paper rigorously validates the superior performance of Boron-Doped Diamond (BDD) electrodes in the rapid and efficient anodic oxidation of high-concern Endocrine Disrupting Compounds (EDCs): Gestodene (GES) and 17α-Ethinylestradiol (EE2).

Exceptional Degradation Speed: Under optimal conditions (32 mA cm⁻², pH 4), the system achieved >93% removal of GES in 5 minutes and >93% removal of EE2 in 10 minutes, with complete degradation (100%) within 15 minutes.
High Mineralization Efficiency: The process resulted in a Chemical Oxygen Demand (COD) removal percentage of 92.11 ± 5.53%, confirming the potent mineralizing capability of BDD electrodes via the generation of physisorbed hydroxyl radicals ([OH]_ads).
Kinetic Validation: Degradation followed a pseudo-first order kinetic profile, driven by a high and constant concentration of the hydroxyl radical species on the BDD surface.
Optimal Operating Parameters: Peak performance was demonstrated at a current density of 32 mA cm⁻² and slightly acidic conditions (pH 4), highlighting the material’s robustness across varied electrochemical environments.
Market Relevance: These findings confirm BDD anodic oxidation as a highly promising Advanced Oxidation Process (AOP) for tertiary wastewater treatment, specifically targeting persistent organic pollutants (POPs) and steroid hormones.

Technical Specifications

The following hard data points were extracted from the research, focusing on the key operational parameters and measured performance under optimal conditions (Treatment 6).

Parameter	Value	Unit	Context
Electrode Material	Boron-Doped Diamond (BDD)	N/A	Anode/Cathode in parallel configuration
Electrode Area (Per Plate)	6.25	cm²	2.5 cm x 2.5 cm working surface
Optimal Current Density	32	mA cm^-2	Achieved maximum efficiency (Treatment 6)
Initial COD Concentration	713	mg L^-1	Average initial concentration
Maximum COD Removal	92.11 ± 5.53	%	Overall mineralization rate
Optimum pH	4	N/A	Adjusted using 10% H₂SO₄
Electrolyte Concentration	0.02	M	Na₂SO₄ supporting electrolyte
Reaction Temperature	26 ± 2	°C	Maintained at room temperature
GES Kinetic Coefficient (k_GES)	0.4206	min^-1	Pseudo-first order rate constant
EE2 Kinetic Coefficient (k_EE2)	0.3209	min^-1	Pseudo-first order rate constant
Time to >93% GES Degradation	5	min	Highly rapid removal
Time to Complete Degradation (Both)	15	min	100% removal of active ingredients

Key Methodologies

The study employed a controlled electrochemical reactor using BDD electrodes under a 3³ factorial design to optimize pollutant removal efficiency.

Electrode Setup: Parallel BDD electrodes were used as the anode and cathode in an undivided electrolytic cell (50 mL working volume), spaced 2 cm apart.
Initial Pollutant Load: The initial concentration ratio was adjusted to mimic pharmaceutical formulations: 625 µg L⁻¹ Gestodene (GES) and 250 µg L⁻¹ 17α-Ethinylestradiol (EE2).
Factorial Design Parameters: The process evaluated the simultaneous influence of three critical factors across three levels each (27 total treatments, performed in triplicate):
- Current Density: 16, 32, and 48 mA cm⁻².
- Supporting Electrolyte (Na₂SO₄) Concentration: 0.02, 0.05, and 0.10 M.
- Reaction Medium pH: 2, 3, and 4 (adjusted using 10% H₂SO₄).
Reaction Environment: Tests were conducted at ambient room temperature (26 ± 2 °C), maintained in complete darkness under constant mechanical agitation (850 rpm).
Monitoring and Analysis: Performance was monitored by quantifying Chemical Oxygen Demand (COD) removal percentages. Active ingredient degradation profiles were determined using high-performance liquid chromatography (RP-HPLC) with UV/Vis detection at 210 nm.
Mechanistic Confirmation: The data confirmed that the BDD surface generates physisorbed hydroxyl radicals ([OH]_ads), which are the primary species responsible for the fast and complete mineralization of the organic load.

6CCVD Solutions & Capabilities

This research reinforces the critical role of high-quality, heavily Boron-Doped Diamond (BDD) materials for high-efficiency Advanced Oxidation Processes (AOPs) in environmental engineering. 6CCVD is an industry leader providing custom BDD solutions engineered to meet the stringent demands of electrochemical applications like endocrine disruptor removal.

Applicable Materials

To replicate or extend this high-performance electrochemical oxidation research, 6CCVD recommends:

Heavy Boron-Doped Polycrystalline Diamond (PCD): Essential for electrochemical oxidation due to its extremely wide potential window, chemical inertness, and ability to generate highly oxidative [OH]_ads radicals efficiently.
- Material Specification: Our BDD wafers provide the heavy doping required for metallic conductivity and superior electrochemical stability under high current densities (e.g., 32 mA cm⁻²).
- Dimensioning: We offer custom BDD plates up to 125mm in diameter, significantly exceeding the 2.5 cm x 2.5 cm used in the study, enabling easy scale-up for industrial/pilot systems.
- Thickness Control: PCD diamond thickness is available from 0.1 µm up to 500 µm, allowing engineers to optimize the electrode for lifespan and application load.

Customization Potential for Scaling Electrochemical Reactors

The study utilized specific, small-scale electrode dimensions. 6CCVD provides comprehensive manufacturing services necessary for prototyping and scaling BDD reactors:

Requirement from Paper	6CCVD Customization Capability	Engineering Advantage
Electrode Size (2.5 cm x 2.5 cm)	Custom Laser Cutting Services: Precise dimensions and complex geometries are fabricated from large BDD wafers (up to 125mm).	Allows direct replication of research geometry or rapid prototyping of scalable parallel plate and mesh reactors.
Contacting/Mounting	Custom Metalization: We apply various metal adhesion layers (Ti, Pt, Au, W, Cu) to the BDD non-active surface.	Ensures low-resistance ohmic contact and reliable electrical current delivery under high operational current densities (32 mA cm⁻²).
Surface Finish	Polishing: PCD surface finish (Ra) < 5 nm.	Optimizes electrolyte flow dynamics and maintains long-term radical generation stability.
Material Supply	Global Shipping: Standard DDU shipping worldwide, with DDP options available.	Ensures reliable and timely delivery of mission-critical diamond electrodes globally.

Engineering Support

6CCVD’s in-house team of PhD material scientists and technical engineers specialize in MPCVD diamond growth and advanced electrochemical applications. We offer consultation and support in:

Doping Optimization: Assisting researchers in selecting the ideal boron doping level for maximum [OH]_ads generation efficiency required for specific pollutant types (like EDCs/POPs).
Reactor Design Consultation: Offering expert guidance on BDD plate thickness, metalization protocols, and integration methods for systems dedicated to wastewater remediation and Advanced Oxidation Processes (AOPs).
Process Extension: Applying the kinetic knowledge gained from this study (pseudo-first order models) to optimize parameters for new or mixed contaminant streams.

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

View Original Abstract

Evidence of the negative effects of several pharmaceutical molecules, such as hormones and steroids, on the environment can be observed throughout the world. This paper presents the results of the anodic oxidation of the mixture of gestodene steroid hormones and 17 α-ethinylestradiol present in aqueous medium. The tests were conducted in an undivided cell containing a working volume of 50 mL, using a Na2SO4 solution as support electrolyte and boron-doped diamond electrodes. The experiments were adjusted to the structure of a 33 factorial design. The evaluated factors were: support electrolyte concentration (0.02, 0.05, and 0.10 M), pH of the reaction media (2, 3, and 4), and current density (16, 32, and 48 mA cm−2). Under the optimum conditions (0.02 M Na2SO4, pH 4, and current density of 32 mA cm−2), the degradation of at least 93% of the initial concentration of gestodene and 17α-ethinylestradiol was reached in a reaction time of 5 and 10 min, respectively. The complete degradation of both molecules required 15 min of reaction. Under these conditions, the degradation profile of the pharmaceutical mixture as each one of the active ingredients, followed a pseudo-first order kinetic behavior (kmix = 0.0321, kGES = 0.4206, and kEE2 = 0.3209 min−1).

Tech Support

Original Source

DOI: https://doi.org/10.2166/wh.2016.104

References

2012 - Standard Methods for the Examination of Water and Wastewater
2007 - Evidence of estrogenic mixture effects on the reproductive performance of fish [Crossref]
2011 - Photo-Fenton degradation of the insecticide esfenvalerate in aqueous medium using a recirculation flow-through UV photoreactor [Crossref]
2013 - TiO2-assisted photocatalytic degradation of diclofenac, metoprolol, estrone and chloramphenicol as endocrine disruptors in water [Crossref]
2013 - Electrochemical remediation of 17α-ethinylestradiol
2007 - Estrogenic environmental endocrine-disrupting chemical effects on reproductive neuroendocrine function and dysfunction across the life cycle [Crossref]
2012 - Sonodegradation of 17a-ethynylestradiol in environmentally relevant matrices: laboratory-scale kinetic studies [Crossref]
2011 - BDD anodic oxidation as tertiary wastewater treatment for the removal of emerging micropollutants, pathogens and organic matter [Crossref]
2007 - Ultrasound-induced destruction of low levels of estrogen hormones in aqueous solutions [Crossref]
2008 - Degradation and estrogenic activity removal of 17β-estradiol and 17α-ethinylestradiol by ozonation and O3/H2O2 [Crossref]