Biomedical Engineering Reference
In-Depth Information
gave a carbon yield of 20-25% in HCl gas, against 10-15% in
nitrogen [24]. This method results in the straight microibrillar
morphology (Fig. 10.16). The ex-cellulose carbon obtained by
600
o
C treatment is nonocrystalline, but treatment at above 2000
o
C
results in graphene planes and graphitic carbon crystallites while
the apparent ibrillar morphology was not changed.
Figure 10.16
SEM image of 600
o
C carbon from spray-dried cotton
microcrystal pyrolyzed in nitrogen (a) and HCl (b) [24].
Table 10.3 shows properties of the cellulose-treated carbon
materials. The 600
o
C carbons have BET surface areas several times
greater than those of original cellulose aerogels because of the
formation of micropore. The 2200
o
C treatment caused signiicant
losses in surface area because of carbon crystallite formation.
Table 10.4 shows the properties of the different carbon material
[24].
Table 10.3
Surface area and pore volume of carbon from tunicate
cellulose [24]
600°C treated
2000°C treated
b
Drying
method,
atmosphere
a
Micropore
c
(cm
3
/g)
Mesopore
c
(cm
3
/g)
Surface area
(m
2
/g)
Surface area
(m
2
/g)
Micropore
(cm
3
/g)
Mesopore
(cm
3
/g)
FD, HCl
533
0.255
0.332
84
0.031
0.247
t-
BuOH, N
2
667
0.309
0.468
137
0.051
0.364
t-
BuOH, HCl
549
0.258
0.626
239
0.090
0.644
a
Atmosphere for pyrolysis.
b
In argon atmosphere.
c
Micropore: 0.5 to 2 nm, mesopore: 2-50 nm.