Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives

Madani, S.H., Biggs, M.J. ORCID: 0000-0002-2131-3677, Rodríguez-Reinoso, F. and Pendleton, P., 2019. Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives. Microporous and Mesoporous Materials, 278, pp. 232-240. ISSN 1387-1811

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Abstract

A unique set of 6 polar adsorptives of relatively large dipole moment and of increasing kinetic diameter were used to probe pore volumes available and their mechanism of adsorption on a well-characterized microporous carbon. Multiple adsorption isotherm measurements were made and repeatable results with relatively small standard deviations in amount adsorbed at low relative pressures were obtained. Inconsistencies were observed between calculated Gurvitsch volumes. Sources of these were analysed and identified as contributions from one or more of: (a) molecular sieve effects; (b) molecular packing effects, and; (c) 2D molecular structure formation due to hydrogen bonding. These inconsistencies were further studied by comparison with pore volumes derived via the Dubinin-Radushkevich (DR) equation. Qualitative analyses of the micropore filling processes were proposed, and substantiated by complementary DR analyses. Although most of the isotherms showed Type I character, recasting the relative pressure axis in logarithmic format highlighted clear differences as contributions from fluid-fluid and fluid-solid interactions during pore filling. Overall, the adsorptives were classified into three groups: (a) polar adsorptives with primarily specific interactions adsorbing as a condensation process over a relatively narrow relative pressure range in a medium and late pressure range (iso-PrOH, MeOH, 2-methyl, 2-butanol, H2O); (b) polar adsorptives with potential for non-specific interactions adsorbing as a condensation process over a relatively narrow pressure range in a medium pressure range (pyridine, iso-PrOH, 2-methyl, 2- butanol); and, (c) halogenated adsorptives adsorbing with an S-shaped uptake extending over a broad relative pressure (dichloromethane).

Item Type: Journal article
Publication Title: Microporous and Mesoporous Materials
Creators: Madani, S.H., Biggs, M.J., Rodríguez-Reinoso, F. and Pendleton, P.
Publisher: Elsevier
Date: April 2019
Volume: 278
ISSN: 1387-1811
Identifiers:
NumberType
10.1016/j.micromeso.2018.11.039DOI
S1387181118306188Publisher Item Identifier
Divisions: Schools > School of Science and Technology
Depositing User: Jonathan Gallacher
Date Added: 05 Dec 2018 14:52
Last Modified: 29 Nov 2019 03:00
URI: http://irep.ntu.ac.uk/id/eprint/35242

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