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Scientists at Northwestern University have developed a revolutionary cement made from the electrification of seawater. In addition to reducing carbon emissions, the innovative material has the potential to make cities more sustainable, ushering in a new era in construction.
The global climate crisis has driven research into carbon capture and storage technologies. cement industry, one of the largest sources of emissions carbon dioxide (CO2), is one of the focuses of these studies.
Now, scientists have found an innovative way to turn this problem into a sustainable solution.
Researchers from Northwestern University (United States) have developed a method to create carbon-negative building materials.
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The process uses seawater, electricity and CO2 to produce cement and concrete which, in addition to reducing emissions, store carbon permanently. The technique also generates hydrogen gas, considered a clean fuel.
Technology inspired by nature
The new approach is inspired by the way corals and mollusks form their shells. While these organisms use biological processes to generate mineral structures, the researchers replaced biology with electricity to trigger chemical reactions in seawater.
The method consists of splitting seawater through electrolysis, generating hydrogen and hydroxide ions.
CO2 is then 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.
Scientists have been able to control the texture and density of these materials by adjusting the experimental conditions. This allows the creation of components with different characteristics, suitable for various applications in civil construction.
"We have shown 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 scientists could replace the sand and gravel used in concrete production.
Furthermore, they can serve as a base for cement, plaster and paints. This innovation can reduce the extraction of sand, a resource intensively exploited by the construction industry.
Cement, concrete, paint and plaster are typically composed of or derived from minerals rich in calcium and magnesium, often extracted from aggregates known as sand. Today, this sand is obtained by mining mountains, riverbeds, coastlines 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 Earth, scientists use electricity and CO2 to grow it directly in seawater.
Carbon storage efficiency
One of the most remarkable aspects of this new technology is the ability of the resulting materials to store an abundance of 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 has retained an abundance of CO2 over millions of years. So this new method mimics a natural process of long-term carbon storage.
Additionally, the process generates hydrogen gas, which can be used as a clean fuel for transportation and other industrial applications.
Potential to reduce industrial emissions
The application of this technology could transform the construction industry into a sector that can help combat climate change. According to Rotta Loria, the process can be directly integrated into cement and concrete factories, allowing CO₂ to be sequestered at the source of emissions.
The researcher stated that we could establish a sustainable cycle where CO2 was captured directly at the source. If concrete and cement plants were located in coastal areas, the nearby ocean could provide raw material for dedicated reactors, where the CO2 would be converted, through 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.
