Page 78 - Gas Adsorption Equilibria

64 Chapter 1

Figure 1.22. Adsorption equilibria data of nitrogen (5.0) on activated carbon (AC)
Norit R1 Extra at T = 298 K for pressures up to 14 MPa equivalent to gas
densities up to [1.50].
Reduced masses measured gravimetrically;
(1) Gibbs surface excess masses

(2) Absolute masses adsorbed
optimization parameter (1.33),
AI (1.49).
(3) Absolute masses adsorbed
= const.. .optimization parameter (1.38),
Langmuir adsorption isotherm (1.49).
(4) Absolute masses adsorbed
= const.. .optimization parameter (1.44),
Langmuir adsorption isotherm (1.49),

The parameters of all the data fitting procedures(1-4), i. e. numerical
values for b, and also dispersions of
fitted to the AIs (1.48), (1.49) respectively are given in Table 1.7. As one can
see, method (1) referring to Gibbs surface excess masses does not lead
to physically acceptable results in the pressure range considered
The quality of correlation of procedures (2-4) is nearly
equal, with all AI-parameters having nearly the same numerical values. From
a physical point of view procedure (4) seems to be most satisfying though we
cannot see any real arguments against procedures (2, 3).