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Northwestern University Scientists Developed Revolutionary Cement Made From Seawater Electrification. Besides Reducing Carbon Emissions, the Innovative Material Has Potential to Make Cities More Sustainable, Promoting a New Era in Civil Engineering.
The global climate crisis has driven research into carbon capture and storage technologies. The cement industry, one of the largest sources of carbon dioxide (CO2) emissions, is one of the focuses of these studies.
Now, scientists have found an innovative way to turn this problem into a sustainable solution.
Researchers at Northwestern University (United States) developed a method to create construction materials with negative carbon emissions.
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The process uses seawater, electricity, and CO2 to produce cement and concrete that, besides reducing emissions, store carbon permanently. The technique also generates hydrogen gas, considered a clean fuel.
Nature-Inspired Technology
The new approach is inspired by how corals and mollusks form their shells. While these organisms use biological processes to generate mineral structures, the researchers replaced biology with electricity to induce chemical reactions in seawater.
The method consists of dividing seawater through electrolysis, generating hydrogen and hydroxide ions.
Next, CO2 is injected into the solution, triggering a chemical reaction that causes hydroxide and bicarbonate ions to combine with calcium and magnesium naturally present in seawater.
This process results in the formation of solid minerals, such as calcium carbonate and magnesium hydroxide, which effectively capture and store carbon.
The scientists were able to control the texture and density of these materials by adjusting the experimental conditions. This allows for the creation of components with different characteristics, suitable for various applications in construction.
“We showed that when we generate these materials, we can fully control their properties, such as chemical composition, size, shape, and porosity. This gives us some flexibility to develop materials suitable for different applications,” said Alessandro Rotta Loria, who led the study.
Replacing Sand in Concrete
The materials created by the scientists can replace sand and gravel used in concrete production.
Moreover, they can serve as a base for cement, plaster, and paints. This innovation may reduce sand extraction, a resource heavily exploited by the construction industry.
Cement, concrete, paint, and plasters are typically composed of or derived from minerals rich in calcium and magnesium, often extracted from aggregates known as sand. Currently, this sand is obtained through mining mountains, riverbeds, coasts, and the ocean floor, Loria explained.
The researcher highlighted that the team developed, in collaboration with Cemex, an alternative approach to obtain sand without the need for mining.
Instead of extracting this resource from the Earth, scientists use electricity and CO2 to cultivate it directly in seawater.
Carbon Storage Efficiency
One of the most notable aspects of this new technology is the ability of the resulting materials to store abundant CO2.
Depending on the mineral composition, it is possible to store more than half the weight of the material in carbon dioxide.
The ideal mixture is composed of 50% calcium carbonate and 50% magnesium hydroxide, allowing for efficient carbon storage.
In nature, calcium carbonate forms limestone, a rock that retains significant amounts of CO2 over millions of years. Thus, this new method mimics a natural long-term carbon storage process.
Additionally, the process generates hydrogen gas, which can be used as clean fuel for transport and other industrial applications.
Potential to Reduce Industrial Emissions
The application of this technology could transform the construction industry into an ally in the fight against climate change. According to Rotta Loria, the process can be integrated directly into cement and concrete factories, allowing for CO₂ capture at the emission source.
The researcher stated that we could establish a sustainable cycle where CO2 is captured directly at the source. If concrete and cement plants are located in coastal areas, the nearby ocean could provide raw materials for dedicated reactors, where CO2 would be converted, using clean electricity, into materials applicable to the construction industry. In this way, these materials would become true carbon sinks.
The findings were published in the journal Advanced Sustainable Systems.
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