Scientists from Northwestern University’s McCormick School of Engineering have created a new carbon-negative building material, using seawater, electricity, and carbon dioxide.
The study that led to this creation was spearheaded by Professor Alessandro Rotta Loria.
Building on previous work in his lab centered around long-term CO2 storage in concrete and electrifying seawater to cement marine soils, Rotta Loria and his team now focused on injecting CO2 into seawater and applying electricity to it in lab-based reactors.
To create the carbon-negative material, the team placed electrodes into seawater and applied an electric current, where the low current split water molecules into hydroxide ions, releasing hydrogen gas, which is used as a clean fuel with various applications.
Keeping the electric current on, the scientists then released a bubbling CO2 gas into the seawater, and as a result, this process changed the chemical composition of the seawater, ramping up the concentration of bicarbonate ions.
The hydroxide and bicarbonate ions reacted with other dissolved ions naturally occurring in seawater, such as calcium and magnesium ones, and the reaction created solid minerals, including, CO2-storing calcium carbonate—a mineral found in limestone and shells—and magnesium hydroxide, which sequesters carbon through further interactions with CO2.
When the material blend is split evenly between calcium carbonate and a magnesium-rich solid, it can hold more than half its own weight in CO2. A later carbonation treatment enables the magnesium-rich part to keep locking away more carbon, creating opportunities beyond CO2 storage and toward performance inside a structure.
Relevant: Paebbl Lands €4 Million EU Grant To Turn Concrete Into A Carbon Sink
By shifting the chemical setup of this reaction, with different variations of electricity current or CO2 flow, the scientists were also able to change the chemical composition, size, shape, and porosity of the created material.
According to the research team, this material could replace other aggregates used in concrete mixes, such as sand and gravel, lowering demand for mined sand from rivers, coasts, and seabeds.
As the novel material can be created in the shape of powders or larger grains, the team is confident that it could be applied in the production of different products besides concrete, including cement, paint, and plaster.
Read more: Carbonaide To Scale Its Carbon Negative Concrete Tech With New $4.4M Funding
