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Title: Microstructural Response of Variably Hydrated Ca-Rich Montmorillonite to Supercritical CO2

We report on ab initio molecular dynamics simulations of Ca-rich montmorillonite systems, in different hydration states in the presence of supercritical CO2. Analysis of the molecular trajectories provides estimates of the relative H2O:CO2 ratio per interspatial cation. The vibrational density of states in direct comparison with dipole moment derived IR spectra for these systems provide unique signatures that can used to follow molecular transformation. In a co-sequestration scenario, these signatures could be used to identify the chemical state and fate of Sulfur compounds. Interpretation of CO2 asymmetric stretch shift is given based on a detailed analysis of scCO2 structure and intermolecular interactions of the intercalated species. Based on our simulations, smectites with higher charge interlayer cations at sub-single to single hydration states should be more efficient in capturing CO2, while maintaining caprock integrity. This research would not have been possible without the support of the office of Fossil Energy, Department of Energy. The computational resources were made available through a user proposal of the EMSL User facility, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.
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Publication Date:
OSTI Identifier:
Report Number(s):
39947; AA7020000
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science & Technology, 48(15):8612-8619
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
Country of Publication:
United States
Ca-montmorillonite; DFT; AIMD; CO2 intercalation; co-sequestration; diffusion; VDOS; IR spectrum; d001; supercritical CO2; Environmental Molecular Sciences Laboratory