Mineralization mechanism of carbon dioxide with illite interlayer cations using molecular dynamics simulation and experiments

Clay minerals can be identified as a prospective target for long-term CO 2 sequestration due to their accessible interlayer cations and periodic sheet structure. Understanding the reactive motion of mineral and fluids has dual advantages of resources and environment. To clarify the storage mechanism, an alternative strategy for CO 2 mineralization was investigated through molecular dynamics (MD) simulation and scCO 2 H 2 O illite experiments. The MD simulation predicts the protonation of non-bridging oxygen (NBO) at the illite surface in the first picoseconds, resulting in HCO 3 - ion formations via the bonding between CO 2 molecules and hydroxyl group dissociated from H 2 O molecules. Surface protonation leads to interlayer K + cations hopping to the illite/fluids interface since the middle stage, mainly after 1 ns of the reaction. The leached K + cations bond with the HCO 3 - ions and later interact with the hydroxyl groups, forming K 2 CO 3 molecules at the interface. In accordance with the experimental results, the K + cations’ concentration in the filtrates progressively increases throughout the reaction. Results of SEM-EDS, Raman and XPS measurements find that free CO 2 clusters in contact with the leached interlayer cations can be converted into carbonate species through the mineralization reaction, precipitating at the surface and thus inducing interlayer swelling. These observations reveal that the clay-related mineralization is estimated to undergo an accumulated process, accessibly enhancing the amount of captured CO 2 . This is a new report that demonstrates the mechanism of CO 2 mineralization in clay minerals, presenting a potential solution for CO 2 sequestration enhancement. Insights into K + cations leaching and mineralization kinetics and their underlying mechanisms during the scCO 2 H 2 O illite reaction is a matter of generalization in clay minerals for CO 2 storage. • Mechanism of CO 2 storage in illite mineral using molecular dynamics simulation and experiments. • Performance of CO 2 molecules and interlayer cations during mineralization. • Leaching and precipitation kinetics at different reaction stages were investigated. • Generalizing a broader approach by understanding the mineralization mechanism of CO 2 with interlayer cations.