Effects of Salinity and the Extent of Water on Supercritical CO2-Induced Phlogopite Dissolution and Secondary Mineral Formation

Hongbo Shao, Jessica R. Ray, and Young-Shin Jun*
Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
Environ. Sci. Technol., 2011, 45 (4), pp 1737–1743
DOI: 10.1021/es1034975
Publication Date (Web): January 11, 2011
Copyright © 2011 American Chemical Society
*Phone: (314) 935-4539; fax: (314) 935-7211; e-mail: ysjun@seas.wustl.edu; internet: http://encl.engineering.wustl.edu/.

Abstract

To ensure the viability of geologic CO2 sequestration (GCS), we need a holistic understanding of reactions at supercritical CO2 (scCO2)−saline water−rock interfaces and the environmental factors affecting these interactions. This research investigated the effects of salinity and the extent of water on the dissolution and surface morphological changes of phlogopite [KMg2.87Si3.07Al1.23O10(F,OH)2], a model clay mineral in potential GCS sites. Salinity enhanced the dissolution of phlogopite and affected the location, shape, size, and phase of secondary minerals. In low salinity solutions, nanoscale particles of secondary minerals formed much faster, and there were more nanoparticles than in high salinity solutions. The effect of water extent was investigated by comparing scCO2−H2O(g)−phlogopite and scCO2−H2O(l)−phlogopite interactions. Experimental results suggested that the presence of a thin water film adsorbed on the phlogopite surface caused the formation of dissolution pits and a surface coating of secondary mineral phases that could change the physical properties of rocks. These results provide new information for understanding reactions at scCO2−saline water−rock interfaces in deep saline aquifers and will help design secure and environmentally sustainable CO2 sequestration projects.

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History

  • Published In Issue February 15, 2011
  • Article ASAPJanuary 11, 2011
  • Received: October 25, 2010
    Accepted: December 28, 2010
    Revised: December 24, 2010

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