Potential for carbon adsorption on concrete: surface XPS analyses.

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• The concrete industry significantly contributes to global carbon dioxide emissions through cement manufacturing (calcination).
• Carbonation, a reverse reaction, typically occurs only on exterior concrete surfaces exposed to atmospheric carbon dioxide and moisture.
• Expanding uses of concrete with increased surface area, like recycled crushed concrete, necessitate understanding its carbon dioxide surface adsorption capabilities.

Purpose of the Study:

• To investigate the surface adsorption of carbon dioxide on hydrated cement mortar.
• To evaluate the potential of recycled concrete as a carbon sequestration material.

Main Methods:

• X-ray photoelectron spectroscopy (XPS) was employed to analyze carbon species present on hydrated cement mortar surfaces.
• Surface analysis was conducted to quantify carbon dioxide uptake.

Main Results:

• XPS analysis revealed rapid and substantial uptake of carbon dioxide on mortar surfaces.
• Carbon dioxide adsorption often exceeded the stoichiometric equivalents of calcination, suggesting surface complexation.
• On pure calcite, excess adsorption reached approximately 30%.

Conclusions:

• Accelerated carbon dioxide surface adsorption on concrete materials is a significant phenomenon.
• Recycled concrete exhibits a notable capacity for carbon dioxide surface adsorption.
• This surface adsorption characteristic holds potential for developing novel carbon sequestration processes.