Electrochemical oxidation and electroanalysis of paracetamol on a boron-doped diamond anode material in aqueous electrolytes
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-02-16 |
| Journal | Journal of Electrochemical Science and Engineering |
| Authors | Kouakou Etienne Kouadio, Kambiré Ollo, Konan Sylvestre Koffi, Lassiné Ouattara |
| Institutions | Université Félix Houphouët-Boigny |
| Citations | 10 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study investigates the use of Boron-Doped Diamond (BDD) electrodes for the dual purpose of detecting and electrochemically degrading paracetamol (acetaminophen) in aqueous solutions.
- High Sensitivity Sensing: BDD demonstrated excellent metallic characteristics and proved highly effective as an electrochemical sensor. Using Differential Pulse Voltammetry (DPV) in Britton-Robinson buffer, the detection limit (LOD) for paracetamol was determined to be 0.167 ”M, which is competitive with or superior to many modified electrode systems.
- Rapid Degradation Kinetics: The electrochemical oxidation process is highly efficient, operating under mass transport control at high current densities (e.g., 70 mA cm-2).
- Concentration Dependence: Degradation efficiency is inversely proportional to initial concentration. For low concentrations (1 mM), 99% oxidation was achieved in just 1 hour at 70 mA cm-2.
- Optimal Conditions: Paracetamol oxidation is significantly favored in acidic media (optimal pH 3) and is strongly promoted by temperature increase.
- Temperature Effect: Increasing the electrolyte temperature from 28 °C to 75 °C accelerated the degradation rate, resulting in 97% paracetamol removal after 2 hours of electrolysis (10 mM solution).
- Intermediate Management: The process involves the formation of colored intermediates (observed as a yellow solution) which are subsequently mineralized, leading to complete discoloration of the solution after 2.5 hours at 70 mA cm-2.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| BDD Film Thickness | ~1 | ”m | Hot-Filament CVD Growth |
| BDD Growth Rate | 0.24 | ”m h-1 | HF-CVD Process |
| Working Electrode Area (Analytical) | 1 | cm2 | Voltammetry Cell |
| Anode/Cathode Area (Preparative) | 16 | cm2 | Electrolysis Cell |
| Optimal Analytical Medium | Britton-Robinson (0.04 M) | N/A | DPV Quantification |
| Detection Limit (LOD) | 0.167 | ”M | DPV on BDD electrode |
| Quantification Limit (LOQ) | 0.559 | ”M | DPV on BDD electrode |
| Applied Current Density Range | 20 to 100 | mA cm-2 | Electrolysis experiments |
| Optimal Degradation pH | 3 | N/A | Highest mineralization rate observed |
| Degradation Efficiency (1 mM, 1 h, 70 mA cm-2) | 99 | % | Highest efficiency achieved |
| Degradation Efficiency (10 mM, 2 h, 70 mA cm-2, 75 °C) | 97 | % | Temperature effect study |
| Electrolyte Flow Rate | 2.7 | mL s-1 | Recirculation pump rate |
| Oxidation Peak Potential (Paracetamol) | ~1.05 | V vs. SHE | Cyclic Voltammetry |
Key Methodologies
Section titled âKey Methodologiesâ- BDD Electrode Synthesis: Boron-doped diamond films were prepared via Hot-Filament Chemical Vapor Deposition (HF-CVD) on low-resistivity p-Si wafers. The process utilized a gas mixture of 1% CH4 in H2 containing trimethylboron, resulting in a film thickness of approximately 1 ”m.
- Electrochemical Characterization: The BDD electrodeâs metallic character and diffusion-controlled kinetics were confirmed using Cyclic Voltammetry (CV) with the Fe(III)/Fe(II) redox couple in 0.3 M H2SO4.
- Electrode Pretreatment (Analytical): Prior to DPV analysis, the BDD electrode was subjected to a two-step electrochemical cleaning: 7 cycles of CV followed by cathodic pretreatment (-2 V for 90 s) in 0.5 M H2SO4, and subsequent anodic pretreatment (2 V for 15 s) in Britton-Robinson buffer.
- Paracetamol Quantification: Differential Pulse Voltammetry (DPV) was employed for highly sensitive concentration monitoring. The Britton-Robinson buffer (pH 7) was selected as the optimal supporting electrolyte due to its superior working range and lowest LOD/LOQ values.
- Preparative Electrolysis Setup: Degradation experiments were conducted in a batch mode setup using a BDD anode (16 cm2) and a Zirconium cathode (16 cm2). A constant current was maintained using a voltage generator, and the solution was continuously recirculated at 2.7 mL s-1.
- Kinetic Analysis: Degradation followed pseudo first-order reaction kinetics. Kinetic constants (k) were determined by plotting -ln(C/C0) versus time at various temperatures.
Commercial Applications
Section titled âCommercial Applicationsâ- Pharmaceutical Wastewater Treatment: BDD anodes are critical components in Advanced Oxidation Processes (AOPs) for the complete mineralization of biologically refractory pharmaceutical compounds, such as paracetamol, found in hospital and manufacturing effluent.
- Water Quality Monitoring (Sensing): The high sensitivity and low detection limit (0.167 ”M) of the BDD sensor platform make it ideal for real-time, trace-level quantification of emerging contaminants (ECs) in environmental waters (rivers, lakes, treated wastewater).
- High-Performance Electrochemical Reactors: BDDâs stability and high oxygen evolution overpotential enable its use in industrial electrochemical reactors requiring high current densities (up to 100 mA cm-2) for efficient oxidation processes without rapid electrode fouling or degradation.
- Process Optimization for Chemical Oxidation: The findings regarding optimal pH (acidic, pH 3) and temperature (75 °C) provide crucial engineering parameters for designing and operating cost-effective electrochemical treatment plants, maximizing contaminant removal while minimizing energy consumption.
View Original Abstract
Electrochemical oxidation of paracetamol on boron-doped diamond (BDD) anode has been studied by cyclic voltammetry and preparative electrolysis. Quantification of paracetamol during electrolysis has been mainly realized by differential pulse voltammetry technique in the Britton-Robinson buffer solutions used as the supporting electrolyte. Various parameters such as current intensity, nature of the supporting electrolyte, temperature, and initial concentration of paracetamol have been investigated. The electrochemical characterization by the outer sphere Fe(III)/Fe(II) redox couple has also been performed, showing the metallic character of BDD electrode. The obtained linear dependency of the oxidation peak current intensity and paracetamol concentration indicates that BDD electrode can be used as an electrochemical sensor for the detection and quantification of paracetamol. The investiÂgation of paracetamol degradation during preparative electrolysis showed that: (i) the degradation rate of paracetamol increases with increase of current intensity applied; (ii) for the initial concentrations of 10, 6 and 1 mM of paracetamol, its oxidation rate reaches 60, 78 and 99 % respectively, after 1 h of electrolysis in 0.3 M H2SO4 (pH 0.6) at applied current density of 70 mA cm-2; (iii) at temperatures of electrolyte solution of 28, 55 and 75 °C, paracetamol oxidation rate reached 85, 92 and 97 % respectively, after 2 h at applied current density of 70 mA cm2. From the investigation of the effect of pH value of electrolyte solution, it appears that oxidation of paracetamol is more favorable in acidic solution at pH 3 than solutions of higher pH values.