Page 154 - Gas Adsorption Equilibria

140 Chapter 3

All the isotherms are in the range of pressure measured of Type I
(IUPAC), [3.31-3.34]. Data have been correlated using an adsorption isotherm
(AI) of the generalized Langmuir type, cp. Chap. 7:

The quantity is the (hypothetical) limiting amount adsorbed for
The parameter b(T) is the reciprocal of the “half-load-pressure”, i. e. the
pressure needed at given temperature (T) to load the sorbent with 50 % of its
limiting load, i. e. The exponent can
be related to the fractal dimension of the sorbent material and the diameter of
the molecule adsorbed, cp. Chap. 7. Numerical values of parameters b,
at T = 298.15 K for the sorptive gases investigated are:

Sorptive gas b Purity of gas
mmol/g (1) (%)
18.89 1.165 0.784 99.995 (4.5)
13.38 0.695 0.725 99.995 (4.5)
CO 8.67 0.457 0.828 99.90 (3.0)
7.68 0.402 0.881 99.996 (4.6)

Relative absolute deviations (f) and dispersions of measured data
and data calculated by fitting to (3.38) using a least square
minimization procedure are given in the table below in percent (%):

Sorptive gas f(%) (%) M
0.47 0.54 17
0.35 0.39 17
CO 0.33 0.41 25
0.40 0.55 23