An innovative process converts CO2 into solid, durable materials that catch carbon.
Use of sea water, electricity and carbon dioxide (CO2), Scientist at Northwestern University have developed a new carbon -negative building material.
If the climate continues to warm up, researchers around the world are looking for ways to grasp CO2 From the atmosphere and store it underground. This method offers several climate parts, but does not use the potential value of Atmospheric Co.2.
Northwestern's new approach concerned2 And convert it into useful materials with which concrete, cement, plaster and color can be made. The process also generates hydrogen gas, a clean fuel with a number of applications, including transport.
The study will be published on March 19 in the magazine Advanced sustainable systems.
“We have developed a new approach that enables us to use seawater to create carbon -negative building materials,” said Alessandro Rotta Loria of Northwestern, who led the study. “Cement, concrete, color and plaster usually consist of minerals on calcium and magnesium base, which we often call from aggregates.
Rotta Loria is the assistant professor for civil and environmental technology in Louis Berger at the McCormick School of Engineering in Northwestern. Jeffrey Lopez, assistant professor for chemical and biological engineering at McCormick, was an important co -author in the study. The other northwest of Rotta Loria and Lopez include Nishu Devi, a postdoctoral student and main author; Xiaohui Gong and Daiki Shoji, Ph.D. Students; And Amy Wagner, former doctoral student. The study also benefited from the contributions of important representatives of the Global F&E Department of Cemex, a global building materials company that is devoted to sustainable construction. This work is part of a broader cooperation between the northwest and Cemex.
Muschel-inspired science
The new study builds on earlier work from Rotta Loria's laboratory to save CO2 In the long term in the concrete and for electrifying sea water to consolidate marine floors. Now he uses findings from these two projects by injecting Co2 Apply to sea water in the laboratory during the stream.
“Our research group tries to use electricity to innovate construction and industrial processes,” said Rotta Loria. “We also like to use sea water because it is a naturally plentiful resource. It is not scarce like fresh water.”
In order to create the carbon negative material, the researchers began to initiate electrodes in sea water and apply an electrical current. The low electrical current divides water molecules in hydrogen gas and hydroxidions. During the electrical current, the researcher had the CO bubbled2 Gas through sea water. This process changed the chemical composition of the water and increased the concentration of bicarbonations.
Finally, the hydroxidions and bicarbonate ions with other dissolved ions such as calcium and magnesium, which naturally occur in sea water. The reaction created solid minerals, including calcium carbonate and magnesium hydroxide. Calcium carbonate acts directly as a carbon sink, while magnesium hydroxide carbon is sequested by further interactions with CO2.
Rotta Loria compares the process with the technique of corals and mollusks with which their shell is formed, which converts the metabolic energy to convert dissolved ions into calcium carbonate. Instead of metabolic energy, however, the researchers used electrical energy to initiate the process and increase mineralization with the injection of CO2.
Double discoveries
The researchers made two significant discoveries through experimentation. They were not only able to grow these minerals in sand, but also could change the composition of these materials by controlled experimental factors, including the voltage and electricity, the flow rate, time and the duration of CO2Injection and flow rate, timing and duration of seawater return in the reactor.
Depending on the conditions, the resulting substances are more strikers and porous or denser and harder – but always mainly consist of calcium carbonate and/or magnesium hydroxide. Researchers can grow the materials around an electrode or directly in solution.
“We have shown that if we create these materials, we can fully control their properties, such as the chemical composition, size, shape and porosity,” said Rotta Loria. “This gives us a certain flexibility to develop materials that are suitable for different applications.”
In concrete, these materials can be used as a replacement for sand and/or gravel-a decisive part of it, which is 60-70% of this ubiquitous building material. Or they can be used to produce cement, plaster and color – all essential surfaces in the built environment.
Save carbon in structures
Depending on the ratio of minerals, the material can hold more than half of its weight in CO2. With a composition of half calcium carbonate and half magnesium hydroxide, for example 1 material bin of the material2. Rotta Loria also says that the material – if it is used to replace sand or powder – would not weaken the strength of concrete or cement.
Rotta Loria imagines that industry could apply the technology in highly scalable, modular reactors – not directly into the ocean – to avoid that ecosystems and sea life disturb.
“This approach would enable complete control over the chemistry of the water sources and water tubs, which are only being thrown into open sea water after adequate treatment and environmental checks,” he said.
Responsible for 8% of the global CO2 Emissions, the cement industry is the fourth largest carbon mitter in the world, according to the World Economic Forum. In combination with concrete production, this number is even higher. Rotta Loria provides for2 Back in concrete and cement to produce more sustainable materials for construction and manufacturing.
“We could create circulatoryity in which we sequestrate Co2 Right at the source, «said Rotta Loria.2 is transformed into materials through clean electricity that can be used for countless applications in the construction industry. Then these materials would really become carbon rinsing. “
Reference: “Electrodeplation of Carbon-Trapping Minerals in Seawater for Variable Electrochemical Potentials and Carbon Dioxide” by Nishu Devi, Xiaohui Gong, Daiki Shoji, Amy Wagner, Alexandre Guerini, Davide Zampini, Jeffrey Lopez and Alessandro F. Rotta Loria, 18 March 2025, Advanced sustainable systems.
Two: 10.1002/adsu.202400943