Premium
On Criteria for Occurrence of Azeotropes in Isothermal and Isobaric Binary Systems
Author(s) -
Missen Ronald W.
Publication year - 2005
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450830407
Subject(s) - azeotrope , isobaric process , isothermal process , thermodynamics , boiling , component (thermodynamics) , activity coefficient , binary number , materials science , boiling point , dilution , mathematics , chemistry , chromatography , distillation , physics , arithmetic , aqueous solution
Criteria are developed for the occurrence of azeotropes in binary nonelectrolyte systems for both isothermal and isobaric situations in terms of liquid‐phase activity coefficients at infinite dilution (γ ∞ ). In the case of isothermal systems at temperature T , for a positive azeotrope, γ ∞ lvc ≥ p * mvc / p * lvc where lvc refers to the less volatile component, mvc to the more volatile component, and p * to saturation vapour pressure at T ; for a negative azeotrope, γ ∞ mvc ≤ p * lvc / p * mvc . In the case of isobaric systems at pressure P , for a minimum‐boiling azeotrope, γ ∞ lvc ( T Bmvc ) ≥ P / p * lvc ( T Bmvc ), where T B refers to the boiling point at P ; for a maximum‐boiling azeotrope, γ ∞ mvc ( T Blvc ) ≤ P / p * mvc ( T Blvc ). The criteria are also given in terms of the parameters of selected correlations for the excess molar Gibbs function ( g E ). Examples of the use of the criteria are provided. Various methods that generate values of γ ∞ can be used in conjunction with the criteria, for example, in screening procedures.