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Title: Pore-size dependence and characteristics of water diffusion in slitlike micropores

Abstract

The temperature dependence of the dynamics of water inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing pore size on the water dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the water molecules is observed as the pore gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation time [tau(0)] of the restricted water on pore size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of water within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the water bound to the pore walls and the ratio theta of this strictly confined water to the total water inside the pore, yielding unique characteristic parameters for water transport in these carbon channels across the investigated temperature range.

Authors:
 [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1261452
Alternate Identifier(s):
OSTI ID: 1195687
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 1; Journal ID: ISSN 1539-3755
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Diallo, S. O.. Pore-size dependence and characteristics of water diffusion in slitlike micropores. United States: N. p., 2015. Web. doi:10.1103/PhysRevE.92.012312.
Diallo, S. O.. Pore-size dependence and characteristics of water diffusion in slitlike micropores. United States. doi:10.1103/PhysRevE.92.012312.
Diallo, S. O.. Thu . "Pore-size dependence and characteristics of water diffusion in slitlike micropores". United States. doi:10.1103/PhysRevE.92.012312. https://www.osti.gov/servlets/purl/1261452.
@article{osti_1261452,
title = {Pore-size dependence and characteristics of water diffusion in slitlike micropores},
author = {Diallo, S. O.},
abstractNote = {The temperature dependence of the dynamics of water inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing pore size on the water dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the water molecules is observed as the pore gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation time [tau(0)] of the restricted water on pore size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of water within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the water bound to the pore walls and the ratio theta of this strictly confined water to the total water inside the pore, yielding unique characteristic parameters for water transport in these carbon channels across the investigated temperature range.},
doi = {10.1103/PhysRevE.92.012312},
journal = {Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics},
number = 1,
volume = 92,
place = {United States},
year = {Thu Jul 16 00:00:00 EDT 2015},
month = {Thu Jul 16 00:00:00 EDT 2015}
}

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Cited by: 10 works
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Works referenced in this record:

Elucidating the porous structure of activated carbon fibers using direct and indirect methods
journal, January 1996


Dynamics of water in confined space (porous alumina): QENS study
journal, August 2001

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