title: X-ray diffraction study of K- and Ca-exchanged montmorillonites in CO2 atmospheres.
abstract: Powder X-ray diffraction shows that K- and Ca-exchanged montmorillonites swell upon interacting with CO(2) at ambient temperatures, depending on their initial hydration state. K-exchanged montmorillonite swells rapidly to a maximum d(001) of ∼12.2 Å. In contrast, Ca-exchanged montmorillonite swells more slowly, but reaches a maximum d(001) of ∼15.1 Å. Reaction kinetics differ significantly between the K- and Ca-exchanged montmorillonite complexes. Expansion of K-exchanged montmorillonite samples was rapid, occurring on time scales of tens of minutes or less. The Ca-exchanged montmorillonite samples continued to expand over periods up to 42 h. Aging of both K- and Ca-exchanged montmorillonite complexes at elevated CO(2) pressure for 1-2 days resulted in greater stability when CO(2) pressure was released. The observed intercalation reactions have important consequences for carbon sequestration: (1) CO(2) absorption by swelling clays may represent a significant pathway for storage of CO(2). (2) The swelling of smectites under CO(2) pressure may have a significant impact on the permeability of caprock formations.
authors.affiliation: Department of Earth and Environmental Sciences, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, United States. giesting@alumni.nd.edu
authors.forename: Paul
authors.initials: P
authors.lastname: Giesting
authors.forename: Stephen
authors.initials: S
authors.lastname: Guggenheim
authors.forename: August F
authors.initials: AF
authors.lastname: Koster van Groos
authors.forename: Andreas
authors.initials: A
authors.lastname: Busch
mesh_terms: D001272:Atmosphere; D001546:Bentonite / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D007700:Kinetics; D011188:Potassium / Q000737:chemistry*; D013997:Time Factors; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D001546:Bentonite; D002245:Carbon Dioxide; D011188:Potassium; D002118:Calcium