| Metadata | Details |
|---|
| Publication Date | 2020-06-19 |
| Journal | Processes |
| Authors | Sandra Maldonado, Manuel A. Rodrigo, Pablo Cañizares, G. Roa, C. Barrera |
| Institutions | University of Castilla-La Mancha, Universidad Autónoma del Estado de México |
| Citations | 13 |
| Analysis | Full AI Review Included |
- Core Technology: Evaluation of 17ß-estradiol (E2) degradation using Boron Doped Diamond (BDD) anodes in a complex synthetic urine/methanol mixture, focusing on optimizing selectivity over natural urine components (uric acid).
- Efficiency Achievement: E2 was efficiently and completely removed. In the best-case scenario, total depletion required electric charges lower than 7 kAh·m-3.
- Kinetic Behavior: E2 degradation exhibits two distinct pseudo-first-order kinetic stages, likely corresponding to the oxidation of soluble E2 followed by E2 contained within micelles.
- Methanol Tolerance: Despite methanol acting as a known hydroxyl radical scavenger, the BDD electrolysis process maintained high efficiency, confirming the robustness of the technology in non-aqueous or mixed solvents.
- Selective Oxidation: Degradation of E2 is favored relative to uric acid under specific conditions: low current densities (e.g., 20 mA·cm-2) and high flowrates.
- Mechanism Insight: These selective conditions promote direct electrochemical oxidation processes on the BDD anode surface, suggesting that direct electron transfer is critical for the preferential removal of hazardous species.
- Value Proposition: The findings enable the design of selective Advanced Oxidation Processes (AOPs) for concentrated hazardous waste streams, allowing for the targeted destruction of high-risk pollutants prior to cheaper biological treatment.
| Parameter | Value | Unit | Context |
|---|
| Anode Material | Boron Doped Diamond (BDD) | N/A | Adamant Technologies Diacell® cell |
| Electrode Area | 78.54 | cm2 | Anode and cathode area |
| BDD Coating Thickness | 2.83 | µm | Diamond film thickness |
| Boron Content | 500 | mg·dm-3 | Boron doping concentration |
| sp3/sp2 Ratio | 217 | N/A | Quality indicator of diamond coating |
| E2 Initial Concentration | 10 | mg·L-1 | Standard concentration tested |
| Uric Acid Initial Concentration | 50 | mg·L-1 | Concentration in synthetic urine |
| Current Density Range | 20 to 100 | mA·cm-2 | Galvanostatic operation range |
| Flowrate Range Tested | 6.77 to 12.833 | mL·s-1 | Recirculation flowrates |
| Minimum Charge for E2 Depletion | < 7 | kAh·m-3 | Achieved at optimal conditions |
| E2 Electrons Exchanged (z) | 92 | e- | Stoichiometric value for full mineralization (C18H24O2) |
| Current Efficiency Trend | Decreases | % | Observed with increasing current density |
| Selectivity Trend (E2/Uric Acid) | Favored | N/A | At low current density and high flowrate |
- Synthetic Waste Preparation: A solution mimicking urine composition (including urea, creatinine, and various salts listed in Table 1) was prepared. 17ß-estradiol (E2) and methanol were added to simulate the concentrated waste stream derived from a proposed adsorption/desorption pre-treatment stage.
- Electrochemical Reactor Setup: Experiments utilized a Diacell® cell featuring BDD electrodes (anode and cathode, 78.54 cm2) in a recirculating galvanostatic system connected to a 1 L glass tank.
- Operational Parameter Variation: The influence of two key parameters was systematically evaluated:
- Current Density (J): Tested at 20, 50, and 100 mA·cm-2 (at constant flowrate).
- Flowrate (Q): Tested at 6.77, 11.66, and 12.833 mL·s-1 (at constant current density, 50 mA·cm-2).
- Pollutant and Intermediate Analysis: E2 and uric acid concentrations were quantified using High-Performance Liquid Chromatography (HPLC). Total reaction intermediates were monitored by summing the chromatographic areas of detected byproducts.
- Kinetic and Efficiency Analysis: Experimental data were fitted to pseudo-first-order kinetic models to determine degradation rate constants (k1 for E2, k2 for uric acid). Faradaic current efficiency (Ef) was calculated based on the moles of E2 removed versus the theoretical charge required for complete mineralization.
- Selectivity Determination: The ratio of kinetic constants (k1/k2) was used to compare the oxidizability of E2 relative to uric acid under different operational conditions, identifying regimes that favor E2 removal.
- High-Hazardous Wastewater Treatment: Direct application for treating concentrated streams containing Endocrine Disrupting Chemicals (EDCs) like E2, particularly in hospital or pharmaceutical manufacturing effluents.
- Integrated AOP/Biological Systems: Implementation as a selective pre-treatment step. The BDD process removes highly toxic, refractory compounds (E2) via selective direct oxidation, rendering the remaining effluent suitable for cost-effective biological degradation of less hazardous organics (like uric acid).
- Concentrate Management: Essential technology for treating concentrated organic solutions (e.g., methanol eluates) generated by adsorption/desorption pre-concentration techniques, maximizing the efficiency of the overall waste management process.
- BDD Electrode Market: Reinforces the demand for high-quality, highly doped BDD anodes (high sp3/sp2 ratio) capable of generating powerful oxidants and sustaining direct oxidation mechanisms in challenging, non-aqueous industrial matrices.
- Decentralized Sanitation: Applicable in systems utilizing source separation (e.g., urine diversion) where concentrated urine streams require specialized treatment to remove hormones and pharmaceuticals before discharge or resource recovery.
View Original Abstract
This work focuses on the evaluation of the degradation of 17β-estradiol in a mixture of synthetic urine and methanol, trying to determine in which conditions the hormone can be more easily degraded than the urine compounds. This is in the frame of an overall study in which the pre-concentration stage with adsorption/desorption technology is evaluated to improve electrolysis efficiency. Results show that this pollutant can be efficiently removed from mixtures of urine/methanol by electrolysis with diamond electrodes. This removal is simultaneous with the removal of uric acid (used as a model of natural pollutants of urine) and leads to the formation of other organic species that behave as intermediates. This opens the possibility of using a concentration strategy based on the adsorption of pollutants using granular activated carbon and their later desorption in methanol. Despite methanol being a hydroxyl radical scavenger, the electrolysis is found to be very efficient and, in the best case, current charges lower than 7 kAh·m−3 were enough to completely deplete the hormone from urine. Increases in the operation current density lead to faster but less efficient removal of the 17β-estradiol, while increases in the operation flowrate do not markedly affect the efficiency in the removal. Degradation of 17β-estradiol is favored with respect to that of uric acid at low current densities and at high flowrates. In those conditions, direct oxidation processes on the surface of the anode are encouraged. This means that these direct processes can have a higher influence on the degradability of the hazardous species and opens the possibility for the development of selective oxidation processes, with a great economic impact on the degradation of the hazardousness of hospitalary wastewater.
- 2018 - TiO2@C Nanostructured Electrodes for the Anodic Removal of Cocaine [Crossref]
- 2005 - Degradation of estradiol and ethinyl estradiol by activated sludge and by a defined mixed culture [Crossref]
- 2010 - Removal of estrone, 17α-ethinylestradiol, and 17ß-estradiol in algae and duckweed-based wastewater treatment systems [Crossref]
- 2016 - Partial degradation of levofloxacin for biodegradability improvement by electro-Fenton process using an activated carbon fiber felt cathode [Crossref]
- 2012 - Compuestos emergentes: Implementación de métodos analíticos para extraer y cuantificar 17b-estradiol, 17a-etinilestradiol, ibuprofeno y naproxeno en agua
- 2009 - A review of the effects of emerging contaminants in wastewater and options for their removal [Crossref]
- 2012 - Removal of 17 β-Estradiol by Electro-Fenton Process
- 2014 - Parameters on 17β-Estradiol degradation by Ultrasound in an aqueous system [Crossref]
- 2016 - Electrochemical degradation of estrone using a boron-doped diamond anode in a filter-press reactor [Crossref]
- 2013 - Degradation of 17β-estradiol in aqueous solution by ozonation in the presence of manganese(II) and oxalic acid [Crossref]