Fabrication and application of boron doped diamond BDD electrode in olive mill wastewater treatment in Jordan

At a Glance

Metadata	Details
Publication Date	2016-08-26
Journal	Journal of Water Reuse and Desalination
Authors	Inshad Jum’h, Arwa Abdelhay, H. Al-Ta’ani, Ahmad Telfah, Mohammad Alnaief
Institutions	German Jordanian University, Friedrich-Alexander-Universität Erlangen-Nürnberg
Citations	18
Analysis	Full AI Review Included

Technical Analysis and Documentation for 6CCVD

Executive Summary

The research successfully demonstrates the highly effective electrochemical treatment of Olive Mill Wastewater (OMW) using Boron Doped Diamond (BDD) anodes. This study validates BDD technology as a superior platform for Advanced Oxidation Processes (AOPs), especially in treating complex, highly polluted industrial effluents.

Core Achievement: Achieved >90% Chemical Oxygen Demand (COD) removal from high-load OMW samples, reaching final concentrations meeting typical legal discharge requirements (e.g., 21 mg/L COD).
Material System: BDD film (8 µm thickness) was fabricated via Hot Filament CVD (HFCVD) onto customized Niobium (Nb) circular grid substrates.
Kinetic Enhancement: Treatment kinetics were significantly accelerated by the addition of supporting electrolytes (Na₂SO₄ and NaCl), demonstrating the effective electro-generation of potent secondary oxidants (S₂O₈^2- and ClO¯).
Processing Time: High-pollution OMW (Sample A and B) reached >90% COD removal in 7 hours, while low-pollution OMW (Sample C) achieved this level in just 2 hours when using combined electrolytes.
Electrode Quality: AFM characterization confirmed a high-quality, crack-free BDD surface featuring well (111)-faceted crystals and an average grain size of 0.7 ± 0.3 µm, essential for maximum electrochemical efficiency.
Broad Applicability: Complete color removal and significant turbidity reduction confirm BDD’s capability to mineralize complex, biorecalcitrant phenolic compounds common in industrial wastewater.

Technical Specifications

Parameter	Value	Unit	Context
BDD Deposition Method	Hot Filament Chemical Vapor Deposition (HFCVD)	N/A	Substrate pretreated via sand blasting and diamond seeding.
BDD Film Thickness	8	µm	Measured on Niobium substrate.
Substrate Material	Pure Niobium (Nb)	N/A	Circular grid geometry.
Electrode Dimensions	90	mm	Diameter (Total area 65 cm² per electrode).
Electrode Separation	2	mm	Parallel plate configuration in reactor.
Doping/Gas Mixture	CH₄ (1%) + B(OCH₃)₃ (small amount)	% / N/A	Used to enhance conductivity.
Current Density	Fixed 3	A	Galvanostatic operating condition.
Initial COD Load (High)	72.9	g/L	Raw OMW Sample A (Milling wastewater).
Initial COD Load (Low)	0.18	g/L	Raw OMW Sample C (Washing wastewater).
Max COD Removal (No Electrolyte)	92	%	Achieved with Sample B.
Max COD Removal (Electrolyte)	>90	%	Achieved with Na₂SO₄/NaCl in all samples.
Final COD (Electrolyte)	21	mg/L	Lowest final concentration (Sample C).
Time to >90% Removal	2 - 7	hours	Fastest time achieved with Na₂SO₄/NaCl.
BDD Avg. Grain Size	0.7 ± 0.3	µm	Measured via Atomic Force Microscope (AFM).

Key Methodologies

The BDD anodes were fabricated and tested under strict galvanostatic conditions to ensure reproducible electrochemical oxidation of the OMW.

Substrate Preparation:
- Niobium circular grids (90 mm diameter, 2.8 mm thick) were chosen for conductivity and structural integrity.
- Surface roughening was performed via sand blasting to maximize adhesion strength and active electrochemical surface area.
- Substrates were cleaned in ethanol and seeded using diamond powder in an ultrasonic bath.
HFCVD Fabrication:
- BDD film was grown using a Hot Filament CVD (HFCVD) machine with two parallel filament rows.
- The precursor gas mixture included Methane (CH₄) at 1% concentration.
- Boron doping was achieved using a small concentration of Boron Trimethyl Ester (B(OCH₃)₃).
- Deposition was continued until an 8 µm film thickness was reached under galvanostatic control.
Electrochemical Reactor Setup:
- A laboratory-scale Plexiglas reactor with a 1,000 cm³ capacity was utilized.
- Electrolysis was performed at a constant working electric current of 3 A (galvanostatic control).
- Temperature was maintained at room temperature using an agitated water bath.
Electrolyte Testing:
- Three conditions were tested: (1) No supporting electrolyte, (2) Na₂SO₄ (0.71% w/v), and (3) Na₂SO₄ (0.71% w/v) plus NaCl (0.06% w/v).
- Performance metrics monitored included COD removal, color/absorbance reduction (at 450 nm), turbidity, and pH variation over time.

6CCVD Solutions & Capabilities: Enabling Next-Generation Electrochemistry

6CCVD is positioned as the ideal material partner to replicate, optimize, and scale the high-performance BDD technology demonstrated in this research. Our capabilities exceed the limitations inherent in HFCVD methods, providing superior uniformity and control essential for industrial applications like wastewater treatment.

Applicable Materials

To replicate the high-performance anodic oxidation achieved in this study, 6CCVD recommends materials optimized for high-current density and robust chemical stability:

6CCVD Material	Properties & Application	Relevance to Research
Heavy Boron-Doped PCD	High conductivity BDD (10¹⁹ - 10²¹ atoms/cm³ B doping), necessary for efficient electro-generation of high-potential oxidants (OH•, S₂O₈^2-, ClO¯).	Direct equivalent to the high-efficiency anode used for COD mineralization.
Conductive Substrates	BDD films grown on standard Niobium (Nb), Titanium (Ti), Tantalum (Ta), or Silicon (Si).	We provide the exact Nb substrate used in the study, or higher-durability Ti substrates, optimized for large-scale grid designs.
Thick BDD Plates	PCD substrates or thick films up to 500 µm, offering extended lifetime and mechanical robustness for demanding industrial reactors.	Ensures long-term operational stability required for commercial wastewater treatment facilities.

Customization Potential

The success of the OMW treatment relies on precise electrode geometry and material quality. 6CCVD provides end-to-end customization services, from synthesis via superior MPCVD technology to final component machining.

Advanced Fabrication (MPCVD Advantage): Unlike HFCVD, 6CCVD utilizes Microwave Plasma CVD (MPCVD), ensuring better control over boron incorporation, resulting in highly uniform conductivity across large areas (plates/wafers up to 125mm) and superior crystal quality, eliminating defects like cracks or peeling observed in less controlled deposition methods.
Custom Dimensions and Geometry: The paper used 90 mm circular grids. 6CCVD offers custom laser cutting and shaping services to produce complex electrode geometries, including expanded metal grids or porous structures, maximizing gas bubble flow and electrochemical contact area.
Thickness Control: We provide precise BDD film thickness control from 0.1 µm to 500 µm (SCD/PCD), allowing engineers to optimize the material cost-to-lifetime ratio for specific electrochemical requirements.
Metalization Capability: For secure electrical contact and reactor integration, 6CCVD offers custom multi-layer metalization schemes (e.g., Ti/W/Au or Ti/Pt) applied directly to the BDD surface or substrate edges.

Engineering Support

This research confirms BDD’s vital role in resource recovery and industrial water treatment. 6CCVD’s in-house team of PhD material scientists and technical engineers specialize in developing custom BDD solutions for AOPs.

We offer comprehensive consultation and support for projects in:

Olive Mill Wastewater (OMW) and other phenolic waste stream remediation.
Electrochemical disinfection and advanced oxidation of persistent organic pollutants (POPs).
Electrochemical generation of powerful oxidants (e.g., ClO¯, O₃, H₂O₂, S₂O₈^2-) for water recycling applications.

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

View Original Abstract

A boron doped diamond (BDD) electrode was employed in an electrochemical reactor to oxidize the phenolic content of Jordanian olive mill wastewater. The BDD anode was fabricated using hot filament chemical vapor deposition on niobium and the morphology of the BDD electrode was characterized using an atomic force microscope. Then, electrolysis batch runs were carried out at laboratory scale to test the effect of different process parameters, namely, initial chemical oxygen demand (COD) load (72.9, 33.8, and 0.18 g/L), the addition of Na2SO4 as supporting electrolyte, and adding NaCl along with Na2SO4, on the efficiency of the treatment process. The results were reported in terms of COD, color and turbidity removal, and pH variation. The experiments revealed that electrochemical oxidation using BDD significantly reduced the COD by 85% with no supporting electrolytes. It was observed that adding Na2SO4 with NaCl brought the COD removal to higher than 90% after 7 hours of treatment for COD loads of 72.9 and 33.8 g/L, and after 2 hours for a COD load of 0.18 g/L. Likewise, color was completely removed regardless of the initial COD load. The turbidity for samples with 72.9 and 33.8 g/L as COD load reached a minimal value of 2.5 and 1 NTU respectively.

Tech Support

Original Source

DOI: https://doi.org/10.2166/wrd.2016.062

References

2013 - Phenol electrooxidation in different supporting electrolytes using boron-doped diamond anodes [Crossref]
2006 - Boron doped diamond electrode for the wastewater treatment [Crossref]
2002 - Decolorization of fresh and stored-black olive mill wastewaters by Geotrichum candidum [Crossref]
1993 - Anaerobic digestion of olive oil mill effluent pretreated and stored in municipal solid waste sanitary landfills [Crossref]
2013 - Treatment of olive mill wastewater by electrolysis on boron doped diamond (BDD) electrode
2006 - Treatment of Fenton-refractory olive oil mill wastes by electrochemical oxidation with boron-doped diamond anodes [Crossref]
2009 - Boron-doped diamond anodic treatment of olive mill wastewaters [Crossref]
2007 - Models of hypochlorite production in electrochemical reactor with plate and porous anodes [Crossref]
2011 - Veratic acid treatment by anodic oxidation with BDD anode [Crossref]