Contact angles, pore condensation, and hysteresis: insights from a simple molecular model.

Citation data:

Langmuir : the ACS journal of surfaces and colloids, ISSN: 0743-7463, Vol: 24, Issue: 21, Page: 12295-302

Publication Year:
2008
Usage 74
Abstract Views 74
Captures 35
Readers 34
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Citations 46
Citation Indexes 46
Repository URL:
https://scholarworks.umass.edu/che_faculty_pubs/480; https://scholarworks.umass.edu/che_faculty_pubs/380
PMID:
18834164
DOI:
10.1021/la801972e
Author(s):
P. A. Monson
Publisher(s):
American Chemical Society (ACS)
Tags:
Materials Science; Physics and Astronomy; Chemistry
article description
We discuss the thermodynamics of adsorption of fluids in pores when the solid-fluid interactions lead to partial wetting of the pore walls, a situation encountered, for example, in water adsorption in porous carbons. Our discussion is based on calculations for a lattice gas model of a fluid in a slit pore treated via mean field density functional theory (MFDFT). We calculate contact angles for pore walls as a function of solid-fluid interaction parameter, alpha, in the model, using Young's equation and the interfacial tensions calculated in MFDFT. We consider adsorption and desorption in both infinite pores and in finite length pores in contact with the bulk. In the latter case, contact with the bulk can promote evaporation or condensation, thereby dramatically reducing the width of hysteresis loops. We show how the observed behavior changes with alpha. By using a value of alpha that yields a contact angle of about 85 degrees and maintaining the bulk fluid in a supersaturated vapor state on adsorption, we find an adsorption/desorption isotherm qualitatively similar to those for graphitized carbon black where pore condensation occurs at supersaturated bulk vapor states in the spaces between the primary particles of the adsorbent.