Environmental Engineering Reference
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was observed at an irradiation time of 6 min, beyond which the pore walls
were destroyed and the efficiency was lowered. The optimum activation
conditions led to the production of a mixed micro- and mesostructured
activated carbon with a total BET surface area of 1223
m
2
.g
-1
, an average
pore size of 2.4 nm and surface acidic groups (see Table 5.16). The adsorp-
tion capacity of the microwave-assisted activated carbon was found to be
382
g.g
-1
, which is much higher than the capacity of the conventionally-
prepared CO
2
activated carbon. The comparison of the dye removal effi-
ciencies of palm tree waste-based adsorbents have been compiled in
Table 5.17.
5.2.7 Coconut
Coconut trees are mainly grown in tropical regions because of the high oil
content of the endosperm utilized in the food industry. The total global
production of the coconut has reached 50 million tons by 2010 and is
increasing steadily. A major fraction of this tree, such as husks, shells, leaves
and stems, is considered as waste. Traditionally these wastes are either left
behind as mulch or used as fertilizer because of their high potash content
[103,104]. However, in the last few decades, coconut waste has found a
vast variety of applications including animal feedstock [105], concrete filler
[106], biodiesel fuel production [105] and thermal insulator [107]. In addi-
tion, similar to other lingocellulosic agricultural wastes, coconut waste is
also used enormously to sequester pollutants such as dye and heavy metal
from wastewater [104].
The removal of dye molecules by coconut bunch waste without any mod-
ification has been elaborated by Hameed
et al.
[108]. The characterization
Table 5.16
Porosity structures of oil palm fiber activated
carbon [102].
Property
Value
BET surface area (
m
2
g
-1
)
1223
Micropore surface area (
m
2
g
-1
)
796
External surface area (
m
2
g
-1
)
427
Langmuir surface area (
m
2
g
-1
)
1827
Total pore volume (
cm
3
.
g
-1
)
0.72
Micropore volume (
cm
3
.
g
-1
)
0.42
Mesopore volume (
cm
3
.
g
-1
)
0.30
Average pore size (Å)
23.57
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