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Comparison of homogeneous and heterogeneous electrochemical advanced oxidation processes for treatment of textile industry wastewater

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-06-09
JournalJournal of Hazardous Materials
AuthorsSié Alain Hien, Clément Trellu, Nihal Oturan, Alain Stéphane Assémian, Bi Gouessé Henri Briton
InstitutionsInstitut National Polytechnique Félix Houphouët-Boigny, Université Gustave Eiffel
Citations52
AnalysisFull AI Review Included

Technical Documentation & Analysis: BDD Anodes for Advanced Electrochemical Oxidation

Section titled “Technical Documentation & Analysis: BDD Anodes for Advanced Electrochemical Oxidation”

This document analyzes the research comparing homogeneous (Electro-Fenton, EF) and heterogeneous (Anodic Oxidation, AO) electrochemical advanced oxidation processes (EAOPs) for textile wastewater treatment, focusing on the critical role of Boron-Doped Diamond (BDD) anodes.

Executive Summary

Section titled “Executive Summary”
  • Superior Mineralization: The hybrid Electro-Fenton process utilizing a BDD anode (EF/BDD) achieved the highest mineralization rate, resulting in 95% Total Organic Carbon (TOC) removal in 6 hours, significantly surpassing AO/BDD (75%) and EF/Pt (52%).
  • BDD Mechanism Advantage: BDD’s non-active surface promotes heterogeneous generation of hydroxyl radicals ($\cdot\text{OH}$) at the anode surface, leading to complete combustion of organic compounds and minimizing the accumulation of toxic aromatic degradation by-products.
  • Operational Flexibility: Anodic Oxidation (AO/BDD) demonstrated a key operational advantage by maintaining high mineralization effectiveness across the effluent’s wide natural pH range (3.0 to 13.4), eliminating the need for costly pH adjustment required by the EF process.
  • Energy Efficiency: EF/BDD exhibited lower specific energy consumption (EC) compared to AO/BDD (55 $\text{kWh (kg TOC)}^{-1}$ vs. 90 $\text{kWh (kg TOC)}^{-1}$ after 4 hours), attributed to the combined generation of oxidants in the bulk and at the anode surface.
  • Critical By-Product Challenge: A major drawback of using BDD anodes in chloride-rich effluents is the high formation rate of toxic chlorate ($\text{ClO}_3^-$) and perchlorate ($\text{ClO}_4^-$), emphasizing the need for precise current control and material optimization.

Technical Specifications

Section titled “Technical Specifications”

The following hard data points were extracted from the study regarding material performance and operational conditions:

ParameterValueUnitContext
Anode MaterialBoron-Doped Diamond (BDD)Thin FilmDeposited on Niobium (Nb) substrate
Anode Dimensions$6 \times 4$$\text{cm}^2$Total surface area $24 \text{ cm}^2$
Initial Effluent pH (Natural)13.40-Highly alkaline textile wastewater
Initial TOC Concentration0.45$\text{g L}^{-1}$High organic loading
Max TOC Removal (EF/BDD)95%Achieved after 6 hours at 200 mA
TOC Removal (AO/BDD)75%Achieved after 6 hours at 200 mA
Current Density (Low)8.3$\text{mA cm}^{-2}$Used for 200 mA experiments
Current Density (High)21$\text{mA cm}^{-2}$Used for 500 mA experiments
Specific Energy Consumption (EF/BDD)55$\text{kWh (kg TOC)}^{-1}$After 4 hours at 500 mA
Specific Energy Consumption (AO/BDD)90$\text{kWh (kg TOC)}^{-1}$After 4 hours at 500 mA
Discoloration Kinetic ($k_1$) EF/BDD7.3$\text{h}^{-1}$Pseudo-first order rate constant
Discoloration Kinetic ($k_1$) AO/BDD0.61$\text{h}^{-1}$Pseudo-first order rate constant
$\text{ClO}_3^- / \text{ClO}_4^-$ Conversion (EF/Pt)< 0.5%Conversion of initial $\text{Cl}^-$ at low current

Key Methodologies

Section titled “Key Methodologies”

The electrochemical processes were conducted using the following setup and parameters:

  1. Reactor Configuration: An undivided cylindrical open batch reactor (230 mL volume) was used, maintained under continuous magnetic agitation.
  2. Power Supply: Experiments were performed under galvanostatic conditions using a DC power supply (Hameg, HM8040-3).
  3. Anode Material: Boron-Doped Diamond (BDD) thin film deposited onto a Niobium (Nb) substrate ($6 \times 4 \text{ cm}^2$) was used for AO/BDD and EF/BDD. Platinum (Pt) was used for EF/Pt comparison.
  4. Cathode Material: Stainless steel AISI 304 ($6 \times 4 \text{ cm}^2$) was used for AO/BDD. Carbon felt ($16 \times 5 \text{ cm}^2$) was used for EF processes.
  5. Anodic Oxidation (AO) Conditions: Plate electrodes were placed face-to-face (2 cm inter-electrode distance). Experiments were run at natural pH 13.4, 8.0, and adjusted pH 3.0.
  6. Electro-Fenton (EF) Conditions: Required initial pH adjustment to 3.0 (using sulfuric acid). Iron (II) sulfate heptahydrate (0.1 mM) was added as the catalyst, and air was continuously bubbled to produce hydrogen peroxide ($\text{H}_2\text{O}_2$) at the cathode.
  7. Current Control: Experiments were performed at constant current intensities of 200 mA, 500 mA, and 1000 mA to study the effect of current density on kinetics and energy consumption.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

This research validates the critical role of high-quality BDD anodes in achieving superior mineralization rates for complex industrial effluents. 6CCVD is uniquely positioned to supply the advanced diamond materials required to replicate, optimize, and scale this technology.

Research Requirement6CCVD Applicable MaterialsCustomization Potential & Technical Advantage
High-Performance BDD Anodes (Lines 3, 91)Boron-Doped Diamond (BDD) Thin FilmsWe supply MPCVD BDD films on various substrates (Nb, Si, Ta) with precise boron doping control, essential for tuning the $\cdot\text{OH}$ generation overpotential and optimizing mineralization efficiency.
Custom Electrode Dimensions (Line 92: $6 \times 4 \text{ cm}^2$)Custom Plates and Wafers6CCVD offers custom dimensions for both Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) plates up to 125mm in diameter, facilitating seamless scale-up from lab-scale ($24 \text{ cm}^2$) to industrial reactors.
High Current Density Operation (Line 321)Robust Diamond ThicknessOur SCD and PCD films are available in thicknesses ranging from 0.1 ”m up to 500 ”m. Thicker films provide superior thermal management and mechanical stability necessary for sustained high-current operation (up to 1000 mA tested).
Mitigating $\text{ClO}_4^-$ Formation (Line 545)Custom Metalization and DopingThe paper suggests alternative anodes to reduce toxic by-products. 6CCVD offers in-house metalization (Au, Pt, Pd, Ti, W, Cu) and can apply custom coatings or provide alternative active anode materials (e.g., $\text{RuO}_2/\text{IrO}_2$ coatings) for EF processes requiring low $\text{ClO}_4^-$ conversion.
Surface Quality for Kinetics (General)Precision Polishing ServicesWe offer ultra-low roughness polishing (Ra < 1 nm for SCD, < 5 nm for inch-size PCD), ensuring optimal and consistent surface morphology for predictable electrochemical kinetics and mass transport control in both AO and EF systems.

Engineering Support

Section titled “Engineering Support”

6CCVD’s in-house PhD team specializes in electrochemical applications and material science. We provide expert consultation to researchers and engineers seeking to optimize BDD properties (doping concentration, thickness, substrate choice) for specific Electrochemical Advanced Oxidation Processes (EAOPs), ensuring the best trade-off between high TOC removal efficiency and minimizing toxic chlorinated by-products.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2010 - Laboratory and pilot plant scale study on the electrochemical oxidation of landfill leachate [Crossref]
  2. 2016 - An integrated (electro- and bio-oxidation) approach for remediation of industrial wastewater containing azo-dyes: understanding the degradation mechanism and toxicity assessment [Crossref]
  3. 2018 - In-situ generation of effective coagulant to treat textile bio-refractory wastewater: optimization through response surface methodology [Crossref]
  4. 2017 - Kinetics of oxidative degradation/mineralization pathways of the antibiotic tetracycline by the novel heterogeneous electro-Fenton process with solid catalyst chalcopyrite [Crossref]
  5. 2006 - Decolorizing dye wastewater from the agate industry with Fenton oxidation process [Crossref]
  6. 2008 - An overview of the application of Fenton oxidation to industrial wastewaters treatment [Crossref]
  7. 2017 - Adsorption of Bezathren dyes onto sodic bentonite from aqueous solutions [Crossref]
  8. 2009 - The occurrence of perchlorate during drinking water electrolysis using BDD anodes [Crossref]
  9. 2015 - Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. an updated review [Crossref]
  10. 2009 - Electro-Fenton process and related electrochemical technologies based on Fenton’s reaction chemistry [Crossref]

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