Molecular cage occupancy of clathrate hydrates at infinite dilution: experimental determination and thermodynamic significance.
This study focuses on the cage occupancy of guest molecules in the infinitely dilute state. At the extreme conditions of highly diluted guest concentrations the direct measurements of the cage occupancy ratio representing the competitive inclusion of multiguest species appear to be so difficult because of spectroscopic intensity limitation, but its thermodynamic significance might be considerable due to the fact that the infinite-dilution value of the cage occupancy ratio can provide the valuable thermodynamic information as a very unique and guest-specific parameter. To experimentally identify gaseous guest populations in structure I (sI) and structure II (sII) cages, we used the solid-state nuclear magnetic resonance (NMR), gas chromatography, and direct gas measurements. Furthermore, we derived the simple and generalized thermodynamic equation related to cage occupancies at infinite dilution from the van der Waals-Platteeuw model. Both experimental and predicted values agree well within the experimental error range.
Seol
Jiwoong
J
Department of Chemical and Biomolecular Engineering (BK21 Program) and Gradute School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea.
Lee
Jong-Won
JW
Kim
Do-Youn
DY
Takeya
Satoshi
S
Ripmeester
John A
JA
Lee
Huen
H