Transport of water in small pores

Shuangyan Xu, Gregory C. Simmons, T. S. Mahadevan, George W. Scherer, Steve Garofalini, Carlos Pacheco

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Experimental measurements of the thermal expansion coefficient (a), permeability (k), and diffusivity (D)of water and 1 M solutions of NaCl and CaCl 2 are interpreted with the aid of molecular dynamics (MD) simulations of water in a 3 nm gap between glass plates. MD shows that there is a layer ∼6Å thick near the glass surface that has a ∼2.3 times higher and D about an order of magnitude lower than bulk water. The measured D is ∼5 times lower than that for bulk water. However, when the MD results are averaged over the thickness of the 3 nm gap, D is only reduced by ∼30% relative to the bulk, so the measured reduction is attributed primarily to tortuosity of the pore space, not to the reduced mobility near the pore wall. The measured a can be quantitatively explained by a volume-weighted average of the properties of the high-expansion layer and the "normal" water in the middle of the pore. The permeability of the porous glass can be quantitatively predicted by the Carman-Kozeny equation, if 6 Å of water near the pore wall is assumed to be immobile, which is consistent with the MD results. The properties and thickness of the surface-affected layer are not affected significantly by the presence of the dissolved salts.

Original languageEnglish
Pages (from-to)5084-5090
Number of pages7
JournalLangmuir
Volume25
Issue number9
DOIs
Publication statusPublished - May 5 2009

Fingerprint

porosity
Molecular dynamics
Water
water
molecular dynamics
Glass
glass
permeability
diffusivity
Thermal expansion
thermal expansion
Salts
salts
expansion
Computer simulation
coefficients
simulation

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Xu, S., Simmons, G. C., Mahadevan, T. S., Scherer, G. W., Garofalini, S., & Pacheco, C. (2009). Transport of water in small pores. Langmuir, 25(9), 5084-5090. https://doi.org/10.1021/la804062e

Transport of water in small pores. / Xu, Shuangyan; Simmons, Gregory C.; Mahadevan, T. S.; Scherer, George W.; Garofalini, Steve; Pacheco, Carlos.

In: Langmuir, Vol. 25, No. 9, 05.05.2009, p. 5084-5090.

Research output: Contribution to journalArticle

Xu, S, Simmons, GC, Mahadevan, TS, Scherer, GW, Garofalini, S & Pacheco, C 2009, 'Transport of water in small pores', Langmuir, vol. 25, no. 9, pp. 5084-5090. https://doi.org/10.1021/la804062e
Xu S, Simmons GC, Mahadevan TS, Scherer GW, Garofalini S, Pacheco C. Transport of water in small pores. Langmuir. 2009 May 5;25(9):5084-5090. https://doi.org/10.1021/la804062e
Xu, Shuangyan ; Simmons, Gregory C. ; Mahadevan, T. S. ; Scherer, George W. ; Garofalini, Steve ; Pacheco, Carlos. / Transport of water in small pores. In: Langmuir. 2009 ; Vol. 25, No. 9. pp. 5084-5090.
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