Page 262 - Gas Adsorption Equilibria
P. 262
248 Chapter 5
with being the ring slit volume
and indicating the sorptive gas density.
The effective mass of the boundary layer of the pendulum occurring
during its motion has to be determined by calibration experiments using non-
adsorbing pellets – preferably quartz glass spheres – having a similar surface
as the sorbent pellets [5.2].
Combining equations (5.25), (5.40) we have for the Gibbs excess mass
adsorbed
with to be calculated from oscillations measurement by (5.39) and the
density to be determined from (T, p)-Measurements using the EOS of
the sorptive gas.
Applying the formalism presented above to measurements performed with
non-adsorbing material for example glass spheres or cylinders of the
size of the original adsorbent pellets, leads similar to (5.42) to the relation
which allows to write as
Here is the net volume of the glass material of mass It most easily
can be measured using buoyancy effects at a microbalance. The experimental
quantity again has to be calculated from Eq. (5.39) referring now to
measurements with the pendulum filled with non-adsorbing material (glass)
[5.2, 5.7]
Auxiliary remarks:
1. The slow motion/laminar flow condition (5.28) does not hold in the
low pressure region as then and hence In