An activity-based formulation for Langmuir adsorption isotherm

Chun Kai Chang, Hla Tun, Chau Chyun Chen

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

This work presents an activity-based formulation for Langmuir adsorption isotherm. Treating adsorption as a chemical reaction between the gas molecule and the adsorption vacant site, the classical Langmuir isotherm model expresses the reaction in terms of the species concentrations. Designed to capture the surface heterogeneity, the proposed thermodynamic Langmuir isotherm model substitutes the species concentrations with the species activities and calculates the species activity coefficients with the adsorption non-random two-liquid activity coefficient model. The resulting isotherm model accurately represents pure component adsorption isotherms for gases with wide varieties of adsorbents including silica gels, activated carbons, zeolites and metal organic frameworks at various temperatures. With three physically meaningful parameters, the model outperforms the classical Langmuir isotherm model for the 98 isotherms of 33 systems examined.

Original languageEnglish
Pages (from-to)375-386
Number of pages12
JournalAdsorption
Volume26
Issue number3
DOIs
StatePublished - Apr 1 2020

Keywords

  • Activity coefficient
  • Adsorption
  • Adsorption non-random two-liquid theory
  • Langmuir isotherm
  • Thermodynamic Langmuir isotherm

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