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A recently developed method for cement production may transform the industry from a leading carbon emitter into a carbon sink. Researchers have detailed this innovative approach in a study published on March 18 in Advanced Sustainable Systems. This process not only has the potential to produce carbon-negative cement but could also adapt to create various other construction materials like paint and plaster that effectively store carbon.
The traditional cement-making process is a significant contributor to global carbon dioxide emissions, accounting for approximately 8 percent of the world’s total emissions. This positions cement as the fourth-largest source of emissions globally, primarily stemming from the extraction of raw materials required for concrete from mountains, riverbeds, and seabeds.
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A collaborative effort between researchers at Northwestern University in Evanston, Illinois, and Cemex, a global cement manufacturer with a focus on innovation in Brügg, Switzerland, has led to the advancement of a more sustainable cement. The team’s method harnesses seawater electrolysis, an innovative technique that applies electricity to seawater, effectively splitting its molecules. This process results in the generation of hydrogen gas, chlorine gas, oxygen, and various minerals, including calcium carbonate, which serves as a key raw material for cement production.
According to Alessandro Rotta Loria, an environmental engineer at Northwestern, while the precipitated minerals generated during seawater electrolysis have posed challenges for hydrogen production due to their tendency to clutter equipment, they could be advantageous for sustainable cement production. The challenge lies in the relatively slow rate of mineral production through electrolysis, which is not sufficient to meet industrial demands. To address this, Rotta Loria and his team initiated laboratory experiments to investigate the mineral formation process during electrolysis and explore ways to enhance this production to improve yields.
In their experiments, the researchers submerged electrodes into seawater, manipulating the applied voltage while also injecting carbon dioxide at varied rates to control the water’s pH levels. This experimentation allowed them to modify the chemical compositions, volumes, and crystal structures of the minerals that precipitated. Such adjustments could lead to the creation of a diverse range of minerals and aggregates suitable for the construction industry.
The team suggests that if the electricity powering this electrolysis comes from renewable sources, the materials produced could achieve not only carbon neutrality but also carbon negativity, effectively sequestering atmospheric carbon dioxide for potentially thousands of years.
Source
www.sciencenews.org