Biomedical Engineering Reference
In-Depth Information
reporting experimental measurements of gases sorption on various
samples of carbon nanotubes [9-12]. Detailed information about
theoretical and experimental studies of gas adsorption on different
samples of monolayer and multi-layer carbon nanotube are presented
in review papers [13, 14], that analyze also the methods of carbon
nanotubes filling by gaseous and also liquid substances. These
methods are based on the capillary phenomena and on the wetting
of the nanotube graphitic surface by liquids of various nature. A
number of studies [15-18] investigated the sorption properties of
the “peapods” formed by the filling of single-walled and multi-walled
nanotubes by fullerene molecules, and reported on the occurrence
of new unique properties in these structures.
Along with the purely practical and technical applications of
gases sorption, it is well known that the experimental study of gas
adsorption on solid surfaces represents also an important method
to examine the structural state of samples of porous and highly
dispersed materials [19-21]. For this purpose, the experimental
isotherms of nitrogen adsorption, obtained at various temperatures
starting from 77 K, have been extensively studied. These isotherms
are used to determine the characteristic values of adsorption heat
and energies, specific surface areas, pore volumes and sizes.
It should be noted that measurements of molecular gases
adsorption in various carbon sorbents, including fullerene C
, have
already been performed in a number of studies [22-26]. In particular,
experimental adsorption isotherms on fullerene C
60
were obtained
60
for N
at 298 K [22]. These experiments
evidenced that the values of CO
and O
at 77 K and for CO
2
2
2
sorption at room temperature
largely exceeded the corresponding values for N
2
at 77 K. This
was explained by two factors: first, the smaller critical diameter of
the CO
and O
2
2
molecule (0.33 nm) can determine an increased opportunity
to penetrate also inside the smaller pores; second, at the higher
temperatures the CO
2
adsorption can occur in a nonequilibrium
2
regime.
Under these conditions, the high rate of adsorbate diffusion
into the inner cavities of a sample can play an important role. This
last issue presupposes the presence of a noticeable microporous
structure for fullerene.
Preliminary results of experiments on oxygen sorption on
the C
fullerene, astralene and activated carbon AG-3 (European
analogue Silcarbon SIL20 with a diameter of 2 mm granules) were
60
