the order of a few grams. For this reason, a variant of the ZLC technique has been
developed using a Swagelok 1/8
00 bulkhead union [6]. Figure 4 shows a comparison
of the traditional ZCL and the extended ZLC unit.
The packing distance in an extended ZLC is approximately 40 mm. This offers
the main advantage to obtain breakthrough curves while limiting the amount of
sample required to few mg (30–50 mg). Compared to conventional breakthrough
systems, the use of small amount of samples has the additional advantage of limiting
the pressure drop of the system, and this is particularly important when dealing with
adsorbents in powder form. The information from the adsorption and desorption
response of the extended ZLC can be used to evaluate also binary equilibrium
properties.
Fig. 4 Detail of extended
ZLC (left) and ZLC (right)
columns
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E. Mangano and S. Brandani