Chemistry Reference
In-Depth Information
Here, some comments will be given for the BET surface areas of SAC. It has
been well known that the superactive carbon adsorbents have extremely large
BET surface areas from 2000-3700 m
2
g
-1
[38].
The BET areas of SAC adsorbents serve one of the important parameters of
adsorption capacity of SAC adsorbents.
However, it should be mentioned that the BET areas of SAC adsorbent do not
indicate the true surface area. As is seen from the plots in Figures 22-24, the
SAC adsorbents have always ultramicropores. It has been pointed out that it is
difficult to determine the surface area of ultramicropores by the BET method [12].
plot by
Figure 24. (a) Adsorption-desorption isotherm of N
2
at 77.4 K and (b) its
superactive carbon (MSP-30-SAC).
Furthermore, as is seen from plots in Figures 22-24,
n
m
corresponds to
=0.60-0.65, which means that co-operative swing into the supermicropores is
superimposed in addition to the adsorption of N
2
molecules on the supermicropore
surface. These two factors make it difficult to evaluate the true surface areas of
SAC adsorbents.
