Page 237 - Gas Adsorption Equilibria

4. Volumetric – Gravimetric Measurements 223

inner surface a microbalance – preferably a magnetic suspension
balance (MSB) – to measure the density of the sorptive gas and an
adsorption chamber (AC) of volume and inner surface including a
set of plates or tubes of volume (V) on the surface (A) of which adsorption
should be measured. Naturally, the whole device is placed in a thermostat and
systems for evacuation (VP) and sorptive gas supply (GS) are provided as well
as manometers (p) and thermometers (T) to control pressure and temperature
inside the vessels.
An experiment to measure adsorption on the surface (A) of the sample
material is started by preparing a certain amount of sorptive gas at pressure
temperature (T) in the storage vessel of volume and the
microbalance vessel where the density of the gas is determined by
buoyancy measurements of a sinker (Si) of known volume.

Figure 4.20. Schematic diagram of an instrument to measure wall adsorption by using the
volumetric – densimetric method.
SV...gas storage vessel, MSB...magnetic suspension balance, AC...adsorption
chamber, GS...gas supply system, VP...vacuum pump, T...thermometer,
p...manometer, Si...sinker, valves.

Laboratory for Thermophysical Properties at the University of Oldenburg, Oldenburg,
Germany.