X-ray diffraction study of k- and ca-exchanged montmorillonites in CO2 atmospheres

Paul Giesting*, Stephen Guggenheim, August F. Koster Van Groos, Andreas Busch

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)


Powder X-ray diffraction shows that K- and Ca-exchanged montmorillonites swell upon interacting with CO2 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 CO2 pressure for 1-2 days resulted in greater stability when CO2 pressure was released. The observed intercalation reactions have important consequences for carbon sequestration: (1) CO2 absorption by swelling clays may represent a significant pathway for storage of CO2. (2) The swelling of smectites under CO2 pressure may have a significant impact on the permeability of caprock formations.

Original languageEnglish
Pages (from-to)5623-5630
Number of pages8
JournalEnvironmental Science and Technology
Issue number10
Publication statusPublished - 15 May 2012

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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