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In situ x-ray diffraction studies of alkyl quaternary ammonium montmorillonite in a CO(2) environment.
MedLine Citation:
PMID:  19191402     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
An in situ study was conducted using an x-ray diffractometer and a specially designed high pressure cell to examine the effects of carbon dioxide at different pressures and temperatures on three different modified montmorillonite species. These organoclays possessed organic pillars of quaternary ammonium surfactant with either one, two, or three long (C(16)-C(18)) alkyl chains attached to expand the galleries of the clay mineral. The three clay species were tested between 50 degrees C and 200 degrees C with carbon dioxide pressures between 0.1 and 8.4 MPa. Under these conditions, the three organoclays exhibited marked differences in their basal spacing depending on the surfactant used. The physical state of the intercalated surfactant was found to be of critical importance, with no changes in basal spacing noted until the organic component began to melt, in spite of CO(2) being present. A pressure effect was also noted which delayed melting of the surfactants as the pressure of the system increased. In all cases, further cation exchange with residual sodium cation present in the galleries was observed in the presence of CO(2) and above the melting state of the surfactant. The study included examination of the effect of rapid depressurization on the clay structure, which produced only a small change in basal spacing.
Authors:
M R Thompson; M P Balogh; R L Speer; P D Fasulo; W R Rodgers
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of chemical physics     Volume:  130     ISSN:  1089-7690     ISO Abbreviation:  J Chem Phys     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2009-02-04     Completed Date:  2009-04-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375360     Medline TA:  J Chem Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  044705     Citation Subset:  -    
Affiliation:
MMRI/CAPPA-D, Department of Chemical Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada.
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