Effect of surface cations on the CO2 capture performance of montmorillonite

This study investigated the adsorption of CO2 on three cation-exchanged montmorillonites (Li-Mt, Na-Mt, K-Mt) using density functional theory (DFT). CO2 adsorption primarily occurred through electrostatic attraction with the surface cation, decreasing in strength: Li-Mt > Na-Mt > K-Mt. Li-Mt showed the strongest adsorption capacity. Significant charge transfer occurred between the CO2 molecule and the montmorillonite surface, facilitated by orbital hybridization between CO2 and surface cations. These interactions formed ionic bonds, stabilizing the adsorbed CO2. The addition of a water molecule affected the adsorption configurations, bond lengths, and the occupancy of CO2 on cation-substituted montmorillonite. This computational analysis provided insights into CO2 capture mechanisms by montmorillonite, highlighting the influence of different surface cations on adsorption efficiency. These findings could inform the design of more effective clay-based materials for carbon capture applications.