Using seawater, electricity and carbon dioxide, researchers have created solid materials that could be used in concrete as a substitute for sand and or gravel.
In collaboration with Cemex, engineers at Northwestern University in the US devised a process to generate carbon-negative material with a low electric current that split water molecules into hydrogen gas and hydroxide ions. The researchers then bubbled CO₂ gas through seawater which changed the chemical composition of the water.
This increased the concentration of bicarbonate ions. The hydroxide ions and bicarbonate ions reacted with other naturally occurring dissolved ions such as calcium and magnesium, producing solid minerals including calcium carbonate (acts as a carbon sink) and magnesium hydroxide (sequesters carbon through further interactions with CO₂).
The McCormick School of Engineering’s researchers discovered they were also able to change the composition of these materials by changing the voltage and current of electricity, flow rate, timing, and duration of seawater recirculation in the reactor.
Co-author of the study and Louis Berger Associate Professor of Civil and Environmental Engineering, Rotta Loria, believes CO₂ could be sequestered at the source by locating concrete and cement plants on shorelines.
“We could use the ocean right next to them to feed dedicated reactors where CO₂ is transformed through clean electricity into materials that can be used for myriad applications in the construction industry. Then, those materials would truly become carbon sinks.”
The study has been published in the journal Advanced Sustainable Systems.
About the author
Desi Corbett
Desi is the Editor of Concrete in Australia, at the helm since December 2013, and our weekly news writer since 2016. Focused on concrete and construction for more than 11 years, her expertise in this field forms part of a journalism career spanning three decades. To get in touch please email desi@corbettcomms.com