| Metadata | Details |
|---|
| Publication Date | 2022-11-14 |
| Journal | Processes |
| Authors | Rebecca Dhawle, Zacharias Frontistis, Dionissios Mantzavinos |
| Institutions | University of Patras, University of Western Macedonia |
| Citations | 10 |
| Analysis | Full AI Review Included |
- Target Contaminant: The breast-cancer drug Anastrozole (ANZ) was successfully degraded using Electrochemical Oxidation (EO) over a Boron-Doped Diamond (BDD) anode.
- Performance Benchmark: Maximum ANZ removal reached 97.5% in 90 minutes at the highest tested current density (12.5 mA cm-2).
- Kinetic Mechanism: Degradation follows pseudo-first-order kinetics, with the rate constant (kapp) doubling from 0.022 to 0.0422 min-1 when the current density was increased from 6.25 to 12.5 mA cm-2.
- Dominant Oxidant: The primary mechanism relies on electro-generated hydroxyl radicals (¡OH), confirmed by inhibition using tert-butanol. The estimated steady-state concentration of ¡OH was 0.77 x 10-13 M at 12.5 mA cm-2.
- Matrix Robustness: The EO process is highly robust, maintaining effectiveness across a wide pH range (3-10) and showing only slight reduction in complex matrices (bottled water and wastewater effluent).
- Chloride Influence: Low chloride concentrations (up to 250 mg L-1) are beneficial due to the generation of secondary oxidants (HOCl, ClO-). However, concentrations above 250 mg L-1 are detrimental due to ¡OH scavenging.
- Economic Feasibility: The Electric Energy per Order (EEO) ranged from 23.1 to 25 kWh m-3/order, indicating that process economics are highly dependent on electricity costs.
| Parameter | Value | Unit | Context |
|---|
| Anode Material | Boron-Doped Diamond (BDD) | B/C = 1000 ppm | Ideal non-active electrode |
| Cathode Material | Stainless Steel | N/A | Counter electrode |
| Active Electrode Area | 16 | cm2 | Used for both anode and cathode |
| Reactor Volume | 200 | mL | Batch mode operation |
| Current Density (j) Range | 6.25 - 12.5 | mA cm-2 | Galvanostatic conditions |
| Initial ANZ Concentration | 0.5 - 2 | mg L-1 | Tested range |
| Supporting Electrolyte | 0.1 | M | Na2SO4 (standard) or NaCl |
| kapp (j = 6.25 mA cm-2) | 0.0224 | min-1 | Inherent pH (6.2) |
| kapp (j = 12.5 mA cm-2) | 0.0422 | min-1 | Inherent pH (6.2) |
| kapp (Optimum pH 3) | 0.0394 | min-1 | j = 6.25 mA cm-2 |
| Estimated [¡OH]ss | 0.77 x 10-13 | M | j = 12.5 mA cm-2, pH 7 |
| ANZ Diffusion Coefficient | 3.1 x 10-7 | cm2/s | Estimated via Cottrell equation |
| EEO Range | 23.1 - 25 | kWh m-3/order | Calculated for 6.25 and 12.5 mA cm-2 |
| Cost Estimate | 3.3 - 3.6 | ⏠m-3/order | Based on EU average electricity prices (0.14 âŹ/kWh) |
- Electrochemical Setup: Experiments were conducted in a 200 mL open plexiglass batch reactor using a BDD anode and a stainless-steel cathode (16 cm2 active area each) under galvanostatic control.
- Electrolyte and pH Control: 0.1 M Na2SO4 was used as the standard supporting electrolyte. Initial pH was adjusted (3, 6.2 inherent, 10) using 1 M NaOH or 1 M H2SO4, but the solution was not buffered.
- Kinetic Measurement: Samples were collected at timed intervals, immediately quenched with methanol (0.3 mL) to halt radical reactions, filtered, and analyzed using High-Pressure Liquid Chromatography (HPLC) with detection at 210 nm.
- Radical Scavenging Test: The role of hydroxyl radicals (¡OH) was confirmed by adding 10 g L-1 of tert-butanol, a known ¡OH scavenger, which resulted in near-complete inhibition of ANZ degradation.
- Competition Kinetics: The absolute kinetic constant (kANZ,HOâ˘) and the steady-state concentration of ¡OH were estimated using competition kinetics, with Benzoic Acid (BA) serving as the probe compound.
- Matrix Evaluation: The process efficiency was tested in three distinct water matrices: ultrapure water (UPW), commercially available bottled water (BW), and secondary treated hospital wastewater effluent (WW).
- Economic Analysis: The energy efficiency was quantified using the Electric Energy per Order (EEO) metric, calculated based on power consumption (P), treatment time (t), volume (V), and the apparent rate constant (kapp).
- Advanced Wastewater Treatment (AWT): BDD EO is highly suitable for tertiary treatment stages in municipal and hospital WWTPs, specifically targeting the removal of persistent organic pollutants (POPs) and emerging contaminants (ECs) like pharmaceuticals (ANZ).
- Water Reclamation and Reuse: The ability of BDD to achieve high mineralization rates and operate effectively across a wide pH range makes it a robust technology for producing high-quality effluent for industrial or agricultural reuse.
- Pharmaceutical Manufacturing Effluent: Direct treatment of concentrated pharmaceutical waste streams, where high current densities can be applied to achieve rapid destruction of active pharmaceutical ingredients (APIs).
- Disinfection and Oxidation: Generation of powerful, non-selective oxidants (¡OH, and active chlorine species in chloride-containing waters) allows for simultaneous disinfection and chemical oxidation of complex organic loads.
- Industrial Process Water Cleanup: Applicable in industries where water matrices are complex (containing high levels of inorganic ions, bicarbonate, or organic matter) but require reliable contaminant destruction without extensive chemical pre-treatment.
View Original Abstract
The electrochemical oxidation (EO) of the breast-cancer drug anastrozole (ANZ) is studied in this work. The role of various operating parameters, such as current density (6.25 and 12.5 mA cmâ2), pH (3-10), ANZ concentration (0.5-2 mg Lâ1), nature of supporting electrolytes, water composition, and water matrix, have been evaluated. ANZ removal of 82.4% was achieved at 1 mg Lâ1 initial concentration after 90 min of reaction at 6.25 mA cmâ2 and 0.1 M Na2SO4. The degradation follows pseudo-first-order kinetics with the apparent rate constant, kapp, equal to 0.022 minâ1. The kapp increases with increasing current density and decreasing solution pH. The addition of chloride in the range 0-250 mg Lâ1 positively affects the removal of ANZ. However, chloride concentrations above 250 mg Lâ1 have a detrimental effect. The presence of bicarbonate or organic matter has a slightly negative but not significant effect on the process. The EO of ANZ is compared to its degradation by solar photo-Fenton, and a preliminary economic analysis is also performed.
- 2018 - Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries [Crossref]
- 2022 - Formulation, optimization, and in vitro evaluation of anastrozole-loaded nanostructured lipid carriers for improved anticancer activity [Crossref]
- 2003 - Pharmacokinetics of third-generation aromatase inhibitors [Crossref]
- 2004 - Anastrozole (ArimidexR) [Crossref]
- 2017 - European demonstration program on the effect-based and chemical identification and monitoring of organic pollutants in European surface waters [Crossref]
- 2010 - Analysis of hormone antagonists in clinical and municipal wastewater by isotopic dilution liquid chromatography tandem mass spectrometry [Crossref]