Differences in the adsorption and diffusion behaviour of water and non-polar gases in nanoporous carbon: role of cooperative effects of pore confinement and hydrogen bonding

Farmahini, Amir H. and Bhatia, Suresh K. (2014) Differences in the adsorption and diffusion behaviour of water and non-polar gases in nanoporous carbon: role of cooperative effects of pore confinement and hydrogen bonding. Molecular Simulation, 41 5-6: 432-445. doi:10.1080/08927022.2014.976640


Author Farmahini, Amir H.
Bhatia, Suresh K.
Title Differences in the adsorption and diffusion behaviour of water and non-polar gases in nanoporous carbon: role of cooperative effects of pore confinement and hydrogen bonding
Journal name Molecular Simulation   Check publisher's open access policy
ISSN 1029-0435
0892-7022
Publication date 2014-11-06
Year available 2014
Sub-type Article (original research)
DOI 10.1080/08927022.2014.976640
Open Access Status
Volume 41
Issue 5-6
Start page 432
End page 445
Total pages 14
Place of publication Abingdon, Oxfordshire, United Kingdom
Publisher Taylor & Francis
Collection year 2014
Language eng
Formatted abstract
We investigate the effect of pore confinement and molecular geometry on the adsorption and self-diffusion of H2O, CO2, Ar, CH4, C3H6, SF6 and C5H12, in a realistic model of nanoporous silicon carbide derived carbon (SiC-DC), constructed using hybrid reverse Monte Carlo simulation. Adsorption isotherms, adsorbate–adsorbate and adsorbate–adsorbent contributions to the isosteric heat of adsorption are determined to study the effect of pore confinement, microporosity and molecular geometry on adsorption of these gases. We describe the cooperative effect of pore confinement and hydrogen bonding on the formation of water clusters and anomalous adsorption behaviour of water compared with non-polar gases. We find that, in contrast to literature results based on the slit-pore model, pore-filling does not occur below the saturation pressure in hydrophobic amorphous carbon materials such as SiC-DC and activated carbon fibre. We also compare self-diffusivities and activation energy barriers of water and non-polar gases in the microporous structure of SiC-DC to identify underlying correlations with molecular properties. We demonstrate that the self-diffusivity of water deviates considerably from the correlation between diffusivity and molecular kinetic diameter observed for non-polar gases. This is attributed to the reduced diffusivity of water, and its relatively large energy barrier at high loadings despite its small kinetic diameter, which is due to the blocking effect of water clusters at pore entries.
Keyword Activation energy barrier
Molecular dynamics
Self-diffusion
Water cluster
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online ahead of print 6 Nov 2014

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2015 Collection
 
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