A new study published in Advanced Sustainable Systems explores how seawater electrolysis can be used to synthesize carbon-trapping minerals through controlled electrodeposition. By combining carbon dioxide (CO2) with variable electrochemical potentials, the researchers aimed to enhance mineral formation for carbon capture and renewable energy applications.
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Background: Electrochemical Innovation with Seawater
Seawater has gained increasing attention as a valuable resource in the transition to clean energy. It covers over 70 % of the planet and contains roughly 97 % of the Earth’s water supply.
In addition to producing hydrogen, seawater electrolysis can also precipitate minerals such as calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2), both of which are useful in construction, environmental remediation, and carbon sequestration.
Seawater electrolysis splits water molecules, generating hydrogen at the cathode and oxygen or chlorine at the anode. The increase in the potential of hydrogen ions (pH) at the cathodic interface promotes mineral precipitation.
Recent studies have shown that injecting CO2 during this process significantly enhances carbon sequestration, providing dual benefits of mineral synthesis and carbon capture. This dual-purpose method formed the basis of the current research.
Study Design: Mineral Synthesis Through CO2 Injection
The researchers developed a method for electrochemically synthesizing CaCO3 and Mg(OH)2 in seawater with simultaneous CO2 injection.
Using custom-built electrochemical reactors, they varied parameters such as:
- Electrochemical potential
- Current density
- CO₂ flow rate
- Reaction time
Experiments ran for three to thirty days. A three-electrode system, including a stainless steel cathode, platinum anode, and a silver/silver chloride (Ag/AgCl) reference electrode, was used. Artificial seawater was prepared to simulate ocean conditions, and CO2 was injected at controlled rates.
To study the resulting minerals, the team used X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) to evaluate mineral structure, composition, and stability.
Key Findings: Optimizing Electrochemical Mineralization
The study found that injecting CO2 during electrolysis significantly increased mineral yield. Higher CO2 flow rates led to faster precipitation of CaCO3 and Mg(OH)2. The optimal condition—a CO2 flow rate of 0.30 sccm and an applied potential of -2.0 V (vs. Ag/AgCl)—produced the highest mineral output.
The electrochemical regime influenced mineral composition, favoring CaCO3 formation over Mg(OH)2. The importance of pH and dissolved inorganic carbon (DIC) concentrations was emphasized in determining mineral saturation states.
As local pH increased due to hydroxide ion (OH⁻) generation at the cathode, mineral precipitation was facilitated. The authors quantified energy consumption, revealing a favorable energy profile for the combined hydrogen production processes and mineral precipitation.
Characterization using SEM confirmed the presence of calcite, aragonite, and brucite, with compositions varying based on electrochemical conditions and CO2 injection rates. Importantly, the ability to control mineral composition through electrochemical settings offers a way to fine-tune materials for specific applications.
Applications for Industry and Environmental Sustainability
This research has significant implications across multiple industries, particularly in construction, manufacturing, and environmental remediation. The synthesized CaCO3 and Mg(OH)2 minerals can be utilized in concrete production, cement manufacturing, and coastal restoration, contributing to sustainable infrastructure.
The dual functionality of this process, producing valuable minerals while capturing CO2, aligns well with global climate goals, offering a promising approach to carbon sequestration.
The ability to electrochemically synthesize these minerals presents a sustainable alternative to traditional mining, reducing environmental impact while enhancing material production. Their potential applications in wastewater treatment, soil stabilization, and beach replenishment further highlight their versatility in addressing environmental challenges.
Conclusion and Next Steps
This study shows that electrochemical mineralization in seawater is a viable strategy for carbon capture and sustainable material synthesis. By adjusting electrochemical settings and CO2 flow, researchers can produce valuable minerals while contributing to climate goals.
Looking ahead, the authors suggest focusing on improving faradaic efficiency, refining reactor designs, and testing the technology at larger scales. The long-term durability of the minerals in real-world environments will also be key to implementation.
If integrated with existing carbon capture systems and powered by renewable energy, this method could offer a scalable, low-impact pathway to reducing global carbon emissions and supporting sustainable resource management.
Journal Reference
Dev, N., et al. Electrodeposition of Carbon-Trapping Minerals in Seawater for Variable Electrochemical Potentials and Carbon Dioxide Injections. 2400943 (2025). DOI: 10.1002/adsu.202400943, https://advanced.onlinelibrary.wiley.com/doi/10.1002/adsu.202400943
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