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Title: Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates

Abstract

The salting out effect, where increasing the ionic strength of aqueous solutions decreases the solubility of dissolved gases is a well-known phenomenon. Less explored is the opposite process where an initially anhydrous system containing a volatile, relatively non-polar component and inorganic ions is systematically hydrated. Expandable clays such as montmorillonite are ideal systems for exploring this scenario as they have readily accessible exchange sites containing cations that can be systematically dehydrated or hydrated, from near anhydrous to almost bulk-like water conditions. This phenomenon has new significance with the simultaneous implementation of geological sequestration and secondary utilization of CO2 to both mitigate climate warming and enhance extraction of methane from hydrated clay-rich formations. Here, the partitioning of CO2 and H2O between Na-, Ca-, and Mg-exchanged montmorillonite and variably hydrated supercritical CO2 (scCO2) was investigated using in situ X-ray diffraction, infrared (IR)spectroscopic titrations, and quartz crystal microbalance (QCM) measurements. Density functional theory calculations provided mechanistic insights. Structural volumetric changes were correlated to quantified changes in sorbed H2O and CO2 concentrations as a function of %H2O saturated in scCO2. Intercalation of CO2 is favored at low H2O/CO2 ratios in the interlayer region, where CO2 can solvate the interlayer cation. As the clay becomesmore » more hydrated and the H2O/CO2 ratio increases, H2O displaces CO2 from the solvation shell of the cation and CO2 tends to segregate. This transition decreases both the entropic and enthalpic driving force for CO2 intercalation, consistent with experimentally observed loss of intercalated CO2.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1194282
Report Number(s):
PNNL-SA-101900
48152; AA7020000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta, 16:248-257
Additional Journal Information:
Journal Name: Geochimica et Cosmochimica Acta, 16:248-257
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Schaef, Herbert T., Loring, John S., Glezakou, Vassiliki Alexandra, Miller, Quin R., Chen, Jeffrey, Owen, Antionette T., Lee, Mal Soon, Ilton, Eugene S., Felmy, Andrew R., McGrail, B. Peter, and Thompson, Christopher J. Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates. United States: N. p., 2015. Web. doi:10.1016/j.gca.2015.03.027.
Schaef, Herbert T., Loring, John S., Glezakou, Vassiliki Alexandra, Miller, Quin R., Chen, Jeffrey, Owen, Antionette T., Lee, Mal Soon, Ilton, Eugene S., Felmy, Andrew R., McGrail, B. Peter, & Thompson, Christopher J. Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates. United States. https://doi.org/10.1016/j.gca.2015.03.027
Schaef, Herbert T., Loring, John S., Glezakou, Vassiliki Alexandra, Miller, Quin R., Chen, Jeffrey, Owen, Antionette T., Lee, Mal Soon, Ilton, Eugene S., Felmy, Andrew R., McGrail, B. Peter, and Thompson, Christopher J. Wed . "Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates". United States. https://doi.org/10.1016/j.gca.2015.03.027.
@article{osti_1194282,
title = {Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates},
author = {Schaef, Herbert T. and Loring, John S. and Glezakou, Vassiliki Alexandra and Miller, Quin R. and Chen, Jeffrey and Owen, Antionette T. and Lee, Mal Soon and Ilton, Eugene S. and Felmy, Andrew R. and McGrail, B. Peter and Thompson, Christopher J.},
abstractNote = {The salting out effect, where increasing the ionic strength of aqueous solutions decreases the solubility of dissolved gases is a well-known phenomenon. Less explored is the opposite process where an initially anhydrous system containing a volatile, relatively non-polar component and inorganic ions is systematically hydrated. Expandable clays such as montmorillonite are ideal systems for exploring this scenario as they have readily accessible exchange sites containing cations that can be systematically dehydrated or hydrated, from near anhydrous to almost bulk-like water conditions. This phenomenon has new significance with the simultaneous implementation of geological sequestration and secondary utilization of CO2 to both mitigate climate warming and enhance extraction of methane from hydrated clay-rich formations. Here, the partitioning of CO2 and H2O between Na-, Ca-, and Mg-exchanged montmorillonite and variably hydrated supercritical CO2 (scCO2) was investigated using in situ X-ray diffraction, infrared (IR)spectroscopic titrations, and quartz crystal microbalance (QCM) measurements. Density functional theory calculations provided mechanistic insights. Structural volumetric changes were correlated to quantified changes in sorbed H2O and CO2 concentrations as a function of %H2O saturated in scCO2. Intercalation of CO2 is favored at low H2O/CO2 ratios in the interlayer region, where CO2 can solvate the interlayer cation. As the clay becomes more hydrated and the H2O/CO2 ratio increases, H2O displaces CO2 from the solvation shell of the cation and CO2 tends to segregate. This transition decreases both the entropic and enthalpic driving force for CO2 intercalation, consistent with experimentally observed loss of intercalated CO2.},
doi = {10.1016/j.gca.2015.03.027},
url = {https://www.osti.gov/biblio/1194282}, journal = {Geochimica et Cosmochimica Acta, 16:248-257},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {7}
}