| Metadata | Details |
|---|
| Publication Date | 2022-10-27 |
| Journal | Environments |
| Authors | Monika R. Snowdon, Shasvat Rathod, Azar Fattahi, Abrar Khan, Leslie M. Bragg |
| Institutions | University of Waterloo, Harvard University |
| Citations | 13 |
| Analysis | Full AI Review Included |
- Core Objective: Comparative assessment of Boron-doped Diamond (BDD) and Mixed-Metal Oxide (MMO) anodes for electrochemical oxidation (EO) of Natural Organic Matter (NOM) in standardized Suwannee River water.
- Performance Comparison: BDD electrodes demonstrated higher NOM oxidation efficiency and greater consistency across varying pH (6.5 and 8.5) and current densities (10 and 20 mA cm-2) compared to MMO.
- Optimal BDD Performance: The BDD-SS configuration achieved 40.2% TOC removal and 75.4% COD removal at the highest tested parameters (pH 8.5, 20 mA cm-2).
- Optimal MMO Performance: MMO-SS achieved the highest overall removal metrics (65.8% TOC, 91.6% COD) but only at the lowest tested parameters (pH 6.5, 10 mA cm-2), showing reduced efficiency at higher pH/current.
- Cost-Effectiveness: BDD-SS exhibited the lowest Specific Energy Consumption (Esp) at 4.4 x 103 kWh kg COD-1 (20 mA cm-2, pH 8.5), confirming BDDâs superior cost-efficiency under strong operating conditions.
- Mechanism Insight: BDDâs non-active surface favors the generation of weakly adsorbed hydroxyl radicals (âąOH), leading to effective mineralization and better breakdown of aromatic NOM structures (lower SUVA increase).
- Conclusion for Engineers: BDD anodes are recommended for surface water pre-treatment, especially where high current densities or fluctuating pH levels are expected, due to their stability and lower long-term energy consumption.
| Parameter | Value | Unit | Context |
|---|
| Anode Materials Tested | BDD, MMO (Ti-based) | N/A | Comparative EO study |
| Cathode Materials Tested | BDD, Stainless Steel (SS) | N/A | Electrode configurations |
| Initial pH Levels Tested | 6.5, 8.5 | N/A | Mimicking natural water alkalinity |
| Current Densities (i) | 10, 20 | mA cm-2 | Applied operational parameters |
| Electrode Surface Area | 10 x 10 x 1 | mm | All electrodes |
| Electrolysis Time | 120 | min | Maximum treatment duration |
| Initial TOC (pH 8.5) | 7.03 | mg L-1 | Standardized water matrix |
| Initial COD (Theoretical) | 21.21 | mg L-1 | Calculated ThOD |
| Initial COD (Measured PeCOD) | 18 | mg L-1 | Measured value (15% lower than ThOD) |
| Highest TOC Removal | 65.8 | % | MMO-SS, pH 6.5, 10 mA cm-2 |
| Highest COD Removal | 91.6 | % | MMO-SS, pH 6.5, 10 mA cm-2 |
| BDD Max COD Removal | 75.4 | % | BDD-SS, pH 8.5, 20 mA cm-2 |
| Lowest Specific Energy Consumption (Esp) | 1.5 x 103 | kWh kg COD-1 | BDD-SS, pH 8.5, 10 mA cm-2 |
| Lowest Esp (High Current) | 4.4 x 103 | kWh kg COD-1 | BDD-SS, pH 8.5, 20 mA cm-2 |
| BDD COD/TOC Ratio (Best) | 0.55 ± 0.4 | N/A | BDD-SS, pH 6.5, 20 mA cm-2 |
| MMO COD/TOC Ratio (Best) | 0.33 ± 0.3 | N/A | MMO-SS, pH 6.5, 10 mA cm-2 |
- Water Matrix Standardization: Synthetic water was prepared using Suwannee River NOM (reference standard) and specific salts (Table 2) to control the initial pH at two extremes (6.5 and 8.5) representative of natural water alkalinity.
- Electrode Configuration: Three two-electrode batch systems were tested: BDD anode/BDD cathode (BDD-BDD), BDD anode/Stainless Steel cathode (BDD-SS), and MMO anode/Stainless Steel cathode (MMO-SS).
- Electrolysis Operation: 300 mL samples were treated in a batch reactor under constant current densities (10 or 20 mA cm-2) for 120 minutes, with a 30-minute equilibration period prior to treatment.
- Particulate Removal: All treated water samples were filtered using a 0.45 ”m polyethersulfone (PES) membrane to remove particulate matter and agglomerates before analysis.
- Organic Matter Quantification: NOM degradation was tracked using four surrogate parameters:
- TOC: Measured via 680 °C combustion catalytic oxidation (Shimadzu TOC-L).
- COD: Measured via photoelectrochemical oxygen demand (PeCOD© Analyzer).
- UV254: Measured via fluorescence plate reader to quantify aromatic/unsaturated carbon bonds.
- SUVA: Calculated by normalizing UV254 by Dissolved Organic Carbon (DOC) to indicate aromaticity changes.
- Energy Efficiency Calculation: Specific Energy Consumption (Esp) was determined using the formula: Esp = (103 * U * I * t) / ((COD0 - CODt) * V), where U is the average cell voltage and V is the water volume.
- Drinking Water Pre-treatment: Utilizing BDD anodes to effectively degrade NOM precursors, thereby minimizing the formation of carcinogenic disinfection by-products (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs) during subsequent chlorination.
- Industrial Wastewater Treatment: Application of BDD EO for the mineralization of recalcitrant organic pollutants (e.g., dyes, pharmaceuticals, landfill leachate) that resist conventional biological or chemical treatments.
- Water Reclamation and Reuse: Employing BDD systems for robust, high-efficiency removal of complex organic loads in municipal and industrial reuse cycles, ensuring high water quality standards.
- Advanced Oxidation Processes (AOP): Integration of BDD electrodes into AOP systems where high overpotential and strong hydroxyl radical generation are required for non-selective oxidation of stable organic molecules.
- Electrode Manufacturing: The study supports the commercial viability of BDD electrodes (fabricated via CVD) as a stable, low-capacitance alternative to traditional MMO anodes, particularly for systems requiring long operational life and resistance to corrosion.
View Original Abstract
The complex composition of natural organic matter (NOM) can affect drinking water treatment processes, leading to perceptible and undesired taste, color and odor, and bacterial growth. Further, current treatments tackling NOM can generate carcinogenic by-products. In contrast, promising substitutes such as electrochemical methods including electrooxidation (EO) have shown safer humic acid and algae degradation, but a formal comparison between EO methods has been lacking. In this study, we compared the Boron-doped diamond (BDD) electrode electrolysis performance for Suwannee River NOM degradation using mixed-metal oxide (MMO) anodes under different pH (6.5 and 8.5) representative of the high and low ranges for acidity and alkalinity in wastewater and applied two different current densities (10 and 20 mA cmâ2). BDD anodes were combined with either BDD cathodes or stainless steel (SS) cathodes. To characterize NOM, we used (a) total organic compound (TOC), (b) chemical oxygen demand (COD), (c) specific ultraviolet absorbance (SUVA), and (d) specific energy consumption. We observed that NOM degradation differed upon operative parameters on these two electrodes. BDD electrodes performed better than MMO under stronger current density and higher pH and proved to be more cost-effective. BDD-SS electrodes showed the lowest energy consumption at 4.4 Ă 103 kWh kg CODâ1. while obtaining a TOC removal of 40.2%, COD of 75.4% and SUVA of 3.4 at higher pH and current. On the contrary, MMO produced lower TOC, COD and SUVA at the lower pH. BDD electrodes can be used in surface water as a pre-treatment in combination with some other purification technologies to remove organic contaminants.
- 2002 - Seasonal variations in the disinfection by-product precursor profile of a reservoir water [Crossref]
- 2007 - Formation of chlorination by-products in waters with low SUVA-correlations with SUVA and differential UV spectroscopy [Crossref]
- 2002 - Fouling characteristics of wastewater effluent organic matter (EfOM) isolates on NF and UF membranes [Crossref]
- 2009 - Models for predicting disinfection by-product (DBP) formation in drinking waters: A chronological review [Crossref]
- 2022 - Pharmaceutical Micropollutant Treatment with UV-LED/TiO2 Photocatalysis under Various Lighting and Matrix Conditions [Crossref]
- 2012 - A review of electrode materials for electrochemical supercapacitors [Crossref]
- 2005 - Characterization of natural organic matter in conventional water treatment processes for selection of treatment processes focused on DBPs control [Crossref]
- 2014 - Critical review of electrochemical advanced oxidation processes for water treatment applications [Crossref]
- 2004 - The water decomposition reactions on boron-doped diamond electrodes [Crossref]