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Analysis of adsorption selectivity in a one‐dimensional model system
Author(s) -
Talbot Julian
Publication year - 1997
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690431010
Subject(s) - selectivity , adsorption , chemistry , mole fraction , component (thermodynamics) , phase (matter) , thermodynamics , rod , analytical chemistry (journal) , chromatography , organic chemistry , physics , medicine , alternative medicine , pathology , catalysis
The adsorption selectivity, S i, j = (X i /y i )/(x j /y j ), is examined in a 1–D model of a mixture of hard rods adsorbing on a linear substrate. The adsorbed components are characterized by their length, l i , and equilibrium constant, k i . We derive an expression for the bulk‐phase pressure P o , for which there is no separation of components i and j, S, i, j = 1, in terms of these parameters. The selectivity of the smaller component always increases with the bulk pressure, which results in a selectivity reversal if, as is usually the case, the larger component is more strongly adsorbed at low surface coverages. In a binary mixture, when P < P o , the selectivity of the smaller component decreases with increasing bulk‐phase mole fraction, y 1 , while for P > P o , the reverse is true. The effect of varying the molecular parameters on the selectivity is also studied.