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The adsorption of various vapors (adsorbates)
having relative vapor pressures of 10-7∼1
by sepiolite and active carbon was studied. Experiments
were carried out at 25℃
in ambient air having 30% relative humidity (RH),
or under reduced pressure without air nor water.
The amounts of adsorbates adsorbed
on sepiolite were about 0.15, 0.011 and 0.0042mmol/g,
for ammonia, pyridine and acetaldehyde, respectively,
under a relative vapor pressure (P/P0)
of 10-5 in ambient air of 30% RH. The
adsorbed amount were about 0.0045mmol/g, for toluene
and styene, respectively, under 10-3@P/P0.
The adsorption is made through the water molecular
layer on the sepiolite. The amounts of adsorbates
adsorbed on sepiolite under reduced pressure without
air nor water, were about 6.0, 2.0 1.5, 1.0, and
0.8mmol/g, for ammonia, pyridine, ethyl acetate,
styrene, and hexane, respectively, under 10-1
P/P0.
On the other hand, the amounts of
adsorbates adsorbed on coconut-shell active carbon
in the air of 30%RH, were about 0.015, 0.011 and
0.008mmol/g, for pyridine, acetaldehyde, and ammonia,
respectively, under 10-5 , P/P0
and were about 0.9, 0.4 and 0.06mmol/g, for acetone,
toluene, and styrene, respectively, under 10-3@P/P0.
On the carbon surface, however, a close relation
was not observed between the amount of adsorption
and the hydrophilic property of the adsorbates tested.
The plots of adsorbed amount of hydtrophilic adsorbates
against P/P0, coincide with the
common line extrapolated from those of these other
adsorbates. The adsorption on the carbon takes place
mainly on its water-free naked surface.
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