Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption

S. Hadi Madani, Saeid Sedghi, Mark J. Biggs, Phillip Pendleton

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid - high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79)K, argon at T=(85, 87, 89)K, and for water and methanol at T=(278, 288, 298)K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. The heat is on: A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site heat.

Original languageEnglish
Pages (from-to)3797-3805
Number of pages9
JournalChemPhysChem
Volume16
Issue number18
DOIs
Publication statusPublished - 21 Dec 2015

Keywords

  • condensation heat
  • gas adsorption
  • isosteric heat of adsorption
  • non-specific interactions
  • specific interactions

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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