Colloids and Surfaces
A: Physicochemical and Engineering Aspects 177 (2001) 57 – 68
New relationships between the characteristic energy of
adsorption and the average effective diameter of carbon
slit-like micropores — the dependence on the type of an
adsorbate
Artur P. Terzyk *, Piotr A. Gauden
Physicochemistry of Carbon Materials Research Group, Department of Chemistry, Faculty of Adsorption and Catalysis,
Nicolaus Copernicus Uniersity, Gagarin Street 7, 87 -100 Torun ´ , Poland
Received 6 January 2000; accepted 4 May 2000
Abstract
As proposed previously for nitrogen, the new derivation of a relationship between the characteristic energy of
adsorption E
0
and the average slit width x of carbon micropores, is applied for other adsorbates i.e. argon, carbon
tetrachloride, benzene and sulphur hexafluoride. Two general relationships considering both the type of an adsorbate
and the parameter n of the Dubinin–Astakhov (DA) equation are developed. It has been shown that using the
proposed relations and the parameters of the DA equation published by other authors (describing the adsorption on
carbon molecular sieves) good correlation is obtained between calculated and suggested pore diameters. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: Activated carbon; Adsorption; Potential theory; Microporosity; Pore diameter
www.elsevier.nl/locate/colsurfa
1. Introduction
It has been widely accepted that there exists a
direct connection between the characteristic en-
ergy of adsorption, E
0
, the parameter determined
from the Polanyi – Dubinin theory of volume
filling of micropores and the average slit width x
of carbon micropores [1]. Plenty of such relations
(see [2]) have been proposed on the basis of both
theoretical and experimental research. Some of
the relationships were developed using the corre-
lation between SAXS and molecular probe data
[3,4]. On the other hand, as shown previously,
[5,6] it is necessary to take into account the
parameter n of the DA equation. Therefore, it has
been proved that the average pore diameter is a
function not only of E
0
but also of n.
Two new relationships were developed (for ni-
trogen adsorbed at 77.5 K) and compared with
relationships proposed by the other authors (see
[5,6] and the references therein). The conclusion
* Corresponding author. Fax: +48-56-6542477.
E-mail address: aterzyk@chem.uni.torun.pl (A.P. Terzyk).
0927-7757/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
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