Webber, J. Beau W. and Anderson, Ross A. and Strange, John H. and Tohidi, Bahman (2007) Clathrate formation and dissociation in vapor/water/ice/hydrate systems in SBA-15, sol-gel and CPG porous media, as probed by NMR relaxation, novel protocol NMR cryoporometry, neutron scattering and ab initio quantum-mechanical molecular dynamics simulation. Magnetic Resonance Imaging, 25 (4). pp. 533-536. ISSN 0730-725X. (Access to this publication is restricted)
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The Gibbs-Thomson effect modifies the pressure and temperature at which clathrates occur, hence altering the depth at which they occur in the seabed. Nuclear magnetic resonance (NMR) measurements as a function of temperature are being conducted for water/ice/ hydrate systems in a range of pore geometries, including templated SBA-15 silicas, controlled pore glasses and sol-gel silicas. Rotator-phase plastic ice is shown to be present in confined geometry, and bulk tetrahydrofuran hydrate is also shown to probably have a rotator phase. A novel NMR cryoporometry protocol, which probes both melting and freezing events while avoiding the usual problem of supercooling for the freezing event, has been developed. This enables a detailed probing of the system for a given pore size and geometry and the exploration of differences between hydrate formation and dissociation processes inside pores. These process differences have an important effect on the environment, as they impact on the ability of a marine hydrate system to re-form once warmed above a critical temperature. Ab initio quantum-mechanical molecular dynamics calculations are also being employed to probe the dynamics of liquids in pores at nanometric dimensions.
|Additional information:||Proceedings paper of the 8th International Bologna Conference on Magnetic Resonance in Porous Media, Bologna, Italy, September 10, 2006|
|Uncontrolled keywords:||Clathrate; Hydrate; Confined geometry; NMR; NMR relaxation; Cryoporometry; Neutron scattering; PVT; Ab initio; Molecular dynamics; Plastic ice; Global warming|
|Subjects:||Q Science > QC Physics|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group
Faculties > Science Technology and Medical Studies > School of Physical Sciences
|Depositing User:||J.B.W. Webber|
|Date Deposited:||06 Oct 2009 12:52|
|Last Modified:||11 Apr 2014 11:34|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/13465 (The current URI for this page, for reference purposes)|