Treatment of Produced Water Using a Pilot-Scale Advanced Electrochemical Oxidation Unit

At a Glance

Metadata	Details
Publication Date	2025-03-12
Journal	Molecules
Authors	Bassam Tawabini, Abdullah A. Basaleh
Institutions	King Fahd University of Petroleum and Minerals
Citations	2
Analysis	Full AI Review Included

Technical Documentation & Analysis: BDD for Advanced Electrochemical Oxidation

Executive Summary

This research validates the critical role of Boron-Doped Diamond (BDD) anodes in the advanced electrochemical oxidation (AEO) of high-salinity produced water (PW). The findings directly support 6CCVD’s expertise in supplying high-performance BDD materials for demanding environmental applications.

Core Achievement: A pilot-scale AEO unit utilizing a BDD anode achieved a maximum Total Organic Carbon (TOC) removal efficiency of 84% (reducing TOC from 250 mg/L to 40 mg/L).
Material Superiority: The study confirms BDD’s exceptional chemical stability and broad potential window (2.3 V vs. SHE) are essential for generating powerful hydroxyl radicals (•OH) necessary for complete organic mineralization in harsh, high-salinity environments (16,200 mg/L TDS).
Optimal Conditions: Maximum efficiency was achieved at high current density (200 mA/cm²) and alkaline conditions (pH 12), demonstrating BDD’s robustness under extreme operating parameters.
Kinetic Insight: At high current densities, the degradation followed pseudo-first-order kinetics, confirming the rapid, continuous generation of excess hydroxyl radicals at the BDD surface.
Scalability Confirmed: The successful operation of the BDD anode in a pilot-scale, plate-and-frame system validates the material’s feasibility for large-scale industrial PW treatment systems.
6CCVD Value Proposition: 6CCVD is uniquely positioned to supply the high-quality, custom-dimension BDD plates required to replicate and scale this highly efficient AEO technology.

Technical Specifications

The following hard data points were extracted from the pilot-scale electrochemical oxidation study:

Parameter	Value	Unit	Context
Anode Material	Boron-Doped Diamond (BDD)	-	Key oxidizing electrode
Cathode Material	Carbon-PTFE	GDE	Gas Diffusion Electrode
Anode Effective Area	0.01 (100)	m² (cm²)	Pilot-scale cell dimension
Initial TOC Concentration	250 ± 30	mg/L	Synthetic Produced Water (PW)
Initial TDS Concentration	16,200 ± 400	mg/L	High salinity environment
Optimal Current Density (C)	200	mA/cm²	Highest TOC removal rate
Optimal pH (B)	12	-	Alkaline conditions favored •OH generation
Optimal Airflow (A)	2	NL/min	Enhanced H₂O₂ electro-generation
Maximum TOC Removal	84	%	Achieved in 4 hours (240 min)
BDD Potential Window	2.3	V	vs. SHE (Enables high oxidation power)
Kinetic Model (High Current)	Pseudo-First Order	-	Dominant at 200 mA/cm²
Kinetic Model (Low Current)	Pseudo-Second Order	-	Dominant at 50 mA/cm²

Key Methodologies

The pilot-scale electrochemical treatment system (ETS) was designed to optimize the removal of organic pollutants from synthetic produced water (PW) using BDD technology.

Synthetic PW Formulation: PW was synthesized to replicate real-world characteristics, featuring high ionic strength (16,200 mg/L TDS) primarily from sodium and calcium chloride, and high organic load (250 mg/L TOC) from crude oil and surfactant (SDS).
Electrochemical Cell Configuration: A modular plate-and-frame Electro MP Cell was utilized, featuring a BDD anode and a carbon-PTFE Gas Diffusion Electrode (GDE) cathode.
Batch Operation: A 2.5 L volume of PW was recirculated through the cell at a constant flow rate of 0.2 m³/h.
Parameter Optimization: The Response Surface Method (RSM) with a Box-Behnken Design (BBD) was employed to systematically investigate the impact of three independent variables on TOC removal:
- Current Density (I): 50, 125, and 200 mA/cm².
- Initial pH: 2, 7, and 12.
- Airflow Rate: 0, 2, and 4 NL/min (fed to the GDE cathode).
Performance Analysis: TOC removal efficiency, current efficiency (% CE), and energy consumption (EC) were calculated. Kinetic models (pseudo-first and pseudo-second order) were applied to understand the degradation mechanism under varying current and pH conditions.

6CCVD Solutions & Capabilities

This research confirms that BDD is the definitive anode material for robust, high-efficiency AEO systems targeting complex industrial wastewater like Produced Water (PW). 6CCVD provides the specialized MPCVD diamond materials and engineering support necessary to deploy this technology at scale.

Applicable Materials

To replicate or extend this research, clients require high-quality, chemically stable Boron-Doped Diamond (BDD) material.

6CCVD Material	Specification	Application Relevance
Heavy Boron Doped PCD	Polycrystalline Diamond (PCD) up to 125mm diameter.	Ideal for large-area industrial anodes requiring high conductivity and extreme corrosion resistance (pH 2 to pH 12).
Heavy Boron Doped SCD	Single Crystal Diamond (SCD) for high-precision applications.	Suitable for R&D or systems requiring ultra-low surface roughness (Ra < 1nm) and maximum uniformity for enhanced electrocatalysis.
Custom BDD Thickness	SCD/PCD layers from 0.1 µm up to 500 µm.	Allows optimization of electrode cost and lifetime based on required current density and operational hours.

Customization Potential

The pilot system utilized an anode area of 0.01 m² (100 cm²). 6CCVD’s manufacturing capabilities are perfectly suited to meet the scaling and integration needs of industrial AEO units.

Large Format Plates: We offer BDD plates and wafers up to 125mm in diameter (PCD), enabling the construction of larger, high-throughput plate-and-frame electrochemical cells, exceeding the dimensions used in this pilot study.
Custom Dimensions and Shapes: 6CCVD provides precision laser cutting and shaping services to produce BDD electrodes that fit specific reactor geometries, ensuring seamless integration into proprietary pilot or full-scale systems.
Integrated Metalization: For robust electrical contact and integration into the cell structure, 6CCVD offers in-house metalization services, including deposition of Ti, Pt, Au, Pd, W, and Cu layers, ensuring low contact resistance and long-term stability under high current loads (up to 200 mA/cm²).
Surface Finish: We provide advanced polishing services, achieving surface roughness down to Ra < 5nm for inch-size PCD, which can influence mass transfer rates and electrode fouling resistance in high-salinity PW treatment.

Engineering Support

The successful optimization of this AEO process relied heavily on complex statistical modeling (RSM) and kinetic analysis.

Application Expertise: 6CCVD’s in-house team of PhD material scientists and electrochemists specializes in BDD applications for Advanced Oxidation Processes (AOPs). We offer consultation on material selection, doping levels, and surface preparation to maximize hydroxyl radical generation and current efficiency for similar Produced Water (PW) or high-salinity brine treatment projects.
Global Logistics: We ensure reliable, global delivery of high-value diamond materials, with DDU (Delivered Duty Unpaid) as the default shipping method and DDP (Delivered Duty Paid) available upon request.

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

View Original Abstract

The main goal of this study is to optimize the treatment of produced water (PW) using a pilot-scale advanced electrochemical oxidation unit. The electro-cell is outfitted with a boron-doped diamond BDD anode and gas diffusion (GDE) cathode. Synthetic PW was prepared in the laboratory following a protocol designed to closely replicate the characteristics of real PW. The PW used in this study had a total dissolved solids (TDS) concentration of 16,000 mg/L and a total organic carbon (TOC) concentration of 250 mg/L. The effect of various electrooxidation parameters on the reduction in TOC was investigated including pH (2-12), electric current (I) (50-200 mA/cm2), and airflow rate (0-4 NL/min). Response surface method RSM with a Box-Behnken design at a confidence level of 95 percent was employed to analyze the impact of the above factors, with TOC removal used as a response variable. The results revealed that the TOC level decreased by 84% from 250 to 40 mg/L in 4 h, current density of 200 mA/cm2, pH of 12, and airflow rate 2 (NL/min). The investigation verified the influential role of diverse operational factors in the treatment process. RSM showed that reducing the airflow rate and increasing pH levels and electric current significantly enhanced the TOC removal. The obtained results demonstrated profound TOC removal, confirming the substantial potential of treating PW using the electrochemical method.

Tech Support

Original Source

DOI: https://doi.org/10.3390/molecules30061272

References

2017 - Microbial distribution and variation in produced water from separators to storage tanks of shale gas wells in Sichuan Basin, China
2017 - An overview on exploration and environmental impact of unconventional gas sources and treatment options for produced water [Crossref]
2019 - Produced water characteristics, treatment and reuse: A review [Crossref]
2023 - A review of waste management approaches to maximise sustainable value of waste from the oil and gas industry and potential for the State of Qatar [Crossref]
2023 - Produced Water Treatment: Review of Technological Advancement in Hydrocarbon Recovery Processes, Well Stimulation, and Permanent Disposal Wells
2024 - Comprehensive insights into the impact of oil pollution on the environment