Reactions involving variably hydrated super critical CO2 (scCO2) and a Na saturated dioctahedral smectite (Na-STX-1) were examined by in situ high-pressure x-ray diffraction at 50°C and two different pressures (90 and 180 bars); conditions that are relevant to long term geologic storage of CO2. Both hydration and dehydration reactions were rapid with appreciable reaction occurring in minutes and near steady state within an hour. Hydration occurred stepwise as a function of increasing H2O in the system; 1W, 2W-3W, and >3W clay hydration states were stable from ~ 1.5-30%, ~31-55
Revised: May 14, 2012 |
Published: April 3, 2012
Citation
Ilton E.S., H.T. Schaef, O. Qafoku, K.M. Rosso, and A.R. Felmy. 2012.In Situ X-Ray Diffraction Study of Na+ Saturated Montmorillonite Exposed to Variably Wet Super Critical CO2.Environmental Science & Technology 46, no. 7:4241-4248.PNNL-SA-85184.doi:10.1021/es300234v