Efficient degradation of phenol by electrooxidation process at boron-doped diamond anode system
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-06-27 |
| Journal | MANAS Journal of Engineering |
| Authors | Nawid Ahmad Akhtar, Mehmet Kobya |
| Institutions | Kyrgyz-TĂźrkish Manas Ăniversity, Gebze Technical University |
| Citations | 1 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis analysis focuses on the high-efficiency degradation of phenol using a Boron-Doped Diamond (BDD) anode in an electrooxidation (EO) system, validating its viability for industrial wastewater treatment.
- Core Achievement: 100% phenol removal (100 mg/L initial concentration) was achieved in a short reaction time of 50 minutes under optimal operating conditions.
- Optimal Parameters: The most efficient operation utilized a BDD anode, a current density of 200 A/m2, an initial pH of 7.6, and a supporting electrolyte concentration (SEc) of 4 g NaCl/L.
- Cost-Effectiveness: The total operating cost (OC) at optimal conditions was calculated as 7.88 $/kg phenol (or 0.99 $/m3), demonstrating competitive economics compared to conventional methods (Table 1).
- Energy Consumption: The specific energy consumption (SEC) required for 100% removal at the optimal point was 420 kWh/kg phenol (12.7 kWh/m3).
- pH Robustness: The BDD anode system successfully degraded phenol across a wide pH spectrum (3.6 to 9.6), suggesting that chemical pH adjustment is often unnecessary, thereby reducing operational costs.
- Efficiency Trade-off: While higher current density (200 A/m2) achieved faster removal, the highest BDD anode efficiency (6.39 g phenol/Ahm2) was observed at the lowest tested current density (50 A/m2).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Anode Material | Boron Doped Diamond (BDD) | Nb/BDD | Non-active electrode for high oxidation potential |
| Cathode Material | Stainless Steel (SS) | 316 AISI SS | Counter electrode |
| Optimal Current Density (j) | 200 | A/m2 | Achieved 100% removal in 50 min |
| Optimal Initial pH | 7.60 | - | Neutral conditions |
| Optimal SE Concentration | 4 | g NaCl/L | Supporting electrolyte |
| Initial Phenol Concentration (Ci) | 100 | mg/L | Optimal test concentration |
| Phenol Removal Time (t) | 50 | min | Time for 100% removal at optimal j |
| Specific Energy Consumption (SEC) | 420 | kWh/kg phenol | At 200 A/m2 (12.7 kWh/m3) |
| Total Operating Cost (OC) | 7.88 | $/kg phenol | At 200 A/m2 (0.99 $/m3) |
| Lowest OC Achieved | 2.31 | $/kg phenol | At 50 A/m2 (slower removal rate) |
| Highest Anode Efficiency (Ρ) | 6.39 | g phenol/Ahm2 | Calculated at 50 A/m2 |
| Lowest Anode Efficiency (Ρ) | 1.74 | g phenol/Ahm2 | Calculated at 200 A/m2 |
| Reactor Volume (V) | 750 | mL | Batch reactor size |
| Anode Active Surface Area (Aelectrode) | 0.012 | m2 | Electrode contact area |
| Electrode Gap | 1.5 | cm | Distance between anode and cathode |
| Electrical Energy Unit Cost (a) | 0.062 | $/kWh | Market price (Kyrgyzstan, March 2025) |
Key Methodologies
Section titled âKey MethodologiesâThe electrooxidation (EO) experiments were conducted in a batch reactor setup to evaluate the BDD anode performance under varying electrochemical and chemical conditions.
- Reactor Configuration: A 750 mL cylindrical glass reactor was used. The BDD anode (Nb/BDD) and the SS cathode (316 AISI SS) were rectangular plates (20 cm length, 6 cm width, 3 mm thickness) positioned vertically and parallel, separated by 1.5 cm.
- Electrochemical Control: A DC power supply (Gwinstek DC SPS-606) was used to maintain constant current densities (j) ranging from 50 to 200 A/m2.
- Solution Preparation: Synthetic phenol wastewater (100-800 mg/L) was prepared using tap water. Sodium chloride (NaCl) was used as the supporting electrolyte (SEc) at concentrations between 2 and 6 g/L.
- Operational Conditions: Experiments were run at room temperature (25 ¹ 1 °C). The solution was continuously agitated using a magnetic stirrer set at 250 rpm to ensure mass transport.
- Parameter Variation: The study systematically investigated the impact of four key variables: current density (j), initial pH (3.6-9.6), initial phenol concentration (Ci), and supporting electrolyte concentration (SEc).
- Analytical Measurement: Phenol concentration was measured using a UV-vis spectrophotometer (Thermo Aquamate 2000E) at 500 nm after complexation with 4-aminoantipyrine. pH and conductivity were monitored using Thermo Scientific Eutech pH 150 and YSI model 30 meters.
Commercial Applications
Section titled âCommercial ApplicationsâBDD electrooxidation is highly suitable for industrial applications requiring robust, chemical-free treatment of persistent organic pollutants (POPs) and high chemical oxygen demand (COD) wastewater.
- Industrial Wastewater Treatment:
- Petrochemical and Refining: Degradation of high-concentration phenolic compounds and other refractory organics found in oil refinery effluents.
- Coke Oven Plants: Effective removal of thiocyanate and phenols from coking wastewater, which are highly toxic and difficult to treat biologically.
- Textile and Dye Industries: Oxidation of complex, non-biodegradable dyes and associated phenolic intermediates.
- Food and Beverage Processing:
- Olive Mill Wastewater: Used as a tertiary polishing step to eliminate residual bioactive phenolic compounds after primary biological treatment.
- Coffee Production: Removal of TOC and COD from instant coffee production wastewater.
- Environmental Remediation:
- Landfill Leachate Treatment: Post-treatment of ultrafiltration effluent from membrane bioreactors (MBR) to remove residual contaminants.
- Electrode Technology:
- BDD anodes are favored in Advanced Oxidation Processes (AOPs) due to their high overpotential for oxygen evolution, promoting the generation of highly reactive hydroxyl radicals (â˘OH) for complete mineralization (oxidation to CO2 and H2O).
View Original Abstract
The rapid increase in global population and industrialization has led to increased environmental pollution, primarily due to insufficient treatment technologies and the depletion of freshwater resources. This research investigates the impact of the electrooxidation (EO) process using Boron Doped Diamond (BDD) anode on phenol degradation, energy consumption, total operating costs, and anode efficiency. The study was carried out on different current densities (j = 50-200 A/m2), initial pH (3.6-9.6), initial phenol concentration (Ci = 100-800 mg/L), and supporting electrolyte concentration (SEc = 2-6 g NaCl/L). The phenol removal efficiency under optimum conditions (anode = BDD, j = 200 A/m2, initial pH = 7.6, Cphenol = 100 mg/L, and SEc = 4 g NaCl/L) was determined to be 100% after 50 min of EO reaction time. However, the energy consumption and total operating cost under these conditions were 12.7 kWh/m3 (420 kWh/kg phenol) and 0.99 $/m3 (7.88 $/kg phenol), respectively. Moreover, BDD anode efficiencies were calculated as 6.39, 3.47, and 1.74 g phenol/Ahm2 at current densities of 50, 100, and 200 A/m2, respectively. Consequently, the EO process is a more cost-effective treatment approach for efficient phenol removal from an aqueous solution.