Tipping Point for Expansion of Layered Aluminosilicates in Weakly Polar Solvents: Supercritical CO 2
- Pacific Northwest National Laboratory, Richland, Washington 99356, United States
- College of Natural Science, Michigan State University, East Lansing, Michigan 48824, United States
- Department of Chemistry and Biochemistry, St. Mary’s College of Maryland, St. Mary’s City, Maryland 20686, United States
- College of Natural Science, Michigan State University, East Lansing, Michigan 48824, United States; Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
- William R. Wiley Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99356, United States
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
Layered aluminosilicates play a dominant role in the mechanical and gas storage properties of the subsurface, are used in diverse industrial applications, and serve as model materials for understanding solvent-ion-support systems. Although expansion in the presence of H2O is well known to be systematically correlated with the hydration free energy of the interlayer cation, in environments dominated by non-polar solvents (i.e. CO2), uptake into the interlayer is not well-understood. Using novel high pressure capabilities, we investigated the interaction of super-critical CO2 with Na+-, NH4+-, and Cs+-saturated montmorillonite, comparing results with predictions from molecular dynamics simulations. Despite the known trend in H2O, and that cation solvation energies in CO2 suggest a stronger interaction with Na+, both the NH4+- and Cs+-clays readily absorbed CO2 and expanded while the Na+-clay did not. The apparent inertness of the Na+-clay was not due to kinetics, as experiments seeking a stable expanded state showed that none exists. Molecular dynamics simulations revealed a large endothermicity to CO2 intercalation in the Na+-clay, but little or no energy barrier for the NH4+- and Cs+-clays. Consequently, we have shown for the first time that in the presence of a low dielectric constant gas swelling depends more on the strength of the interaction between interlayer cation and aluminosilicate sheets and less on that with solvent. The finding suggests a distinct regime in layered aluminosilicates swelling behavior triggered by low solvent polarizability, with important implications in geomechanics, storage and retention of volatile gases, and across industrial uses in gelling, decoloring, heterogeneous catalysis, and semi-permeable reactive barriers.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Fossil Energy (FE)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1408198
- Report Number(s):
- PNNL-SA-127664; 48820; 48812; KC0302060
- Journal Information:
- ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 42 Vol. 9; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
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