The oceans are rich in magnesium resources, which that could be used in the production of construction materials. Sorel cement (magnesium cement), for example, can be used in interior building applications as an alternative to screed. Extracting magnesium from seawater traditionally requires a highly energy-intensive calcination process to isolate magnesium oxide (magnesia). The innovative method of electrolysis-controlled water splitting can bypass this process, significantly reducing CO₂ emissions.
To obtain the precursor of magnesia, magnesium hydroxide (Mg[OH]₂), an alkaline solution must be produced. While previous research has investigated electrochemical methods for hydroxide production, few studies have combined efficient alkali synthesis with the direct precipitation of magnesium hydroxide to make magnesia for low-carbon cement. This critical knowledge gap in optimizing energy and material efficiency has now been addressed.
A new study led by a research team at Columbia University used electrochemical water splitting at low voltages (1.6–2.0 V). Hydroxide ions (OH⁻) were generated from seawater through hydrogen production. This led to the direct precipitation of magnesium hydroxide. The findings were recently published in the journal Desalination. This new approach reduces energy intensity by 52–78%. Normally, the energy consumption per ton of MgO is 0.56 MWh. With the new method, carbon emissions per ton of magnesia can be reduced by up to 0.41 tons of CO₂.
To further improve production efficiency, the nanostructure of magnesium hydroxide was optimized using urea as a crosslinker. This enhanced its reactivity, porosity, and specific surface area. At an optimal urea concentration of 0.2 mol/L, magnesia particles exhibited excellent binding properties. The researchers attributed this to the sealing effects of rosette-shaped dypingite and rod-shaped nesquehonite. According to the authors, the formation of these minerals facilitates CO₂ incorporation and enhances carbonate hardening.
Advances in symmetric electrochemical systems, as demonstrated in this study, result in up to a 78% reduction in energy demand for the production of alkaline solutions. This gives these methods the potential to serve as viable alternatives to traditional processes. The further optimization of electrodes and electrolytes represents a pioneering approach to the carbon-neutral production of building materials and alkalis. Additionally, this method highlights how construction material manufacturing can efficiently lead to large-scale CO₂ mineralization. As a result, the greenhouse gas can be permanently removed from the atmosphere.
The industrial scaling of electrochemical alkali production can reduce operating costs, minimize environmental impact, and improve the properties of low-carbon building materials. The economic aspects of this manufacturing process are particularly noteworthy, as the demand for efficient binding materials continues to grow.
At Frontis Energy, we are committed to promoting sustainable and economically viable energy solutions. Research like this provides valuable insights and innovations to support such sustainable advancements.
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