Environmental Engineering Reference
In-Depth Information
Table 5.20
Comparison of adsorption capacities of coconut waste-based
materials.
Modification
Surface Area
(
m
2
g
-1
)
Dye
Ty p e
pH
Adsorption
Capacity
(
mg.g
-1
))
Ref.
N/A
…
Methylene
Blue
7
70.9
[108]
N/A
…
Methylene
Blue
6
29.5
[131]
H
2
SO
4
- Carbonization
556.3
Crystal
Violet
6
85.8
[132]
H
3
PO
4
- Carbonization
328.2
60.4
Reactive
Red
189.9
[133]
ZnCl
2
- CO
2
Activation
1884
Methylene
Blue
…
15.2
[111]
Remazol
Ye l l o w
176.1
Carbonization - NaOH -
Activation
2825
Methylene
Blue
6.5
916.3
[109]
Carbonization - KOH -
CO
2
Activation
1940
Methylene
Blue
6.5
434.8
[110]
to be used as niche adsorbents for the removal of heavy metals, dyes and
organics from wastewater.
Tea and coffee wastes have been reported to have good dye adsorp-
tion capacity by several researchers. These wastes were used as adsorbents
with or without physical and/or chemical modification. The adsorption of
methylene blue by spent tea leaves has been studied by Hameed [113]. The
tea leaves were thoroughly washed to remove any color or other impu-
rities and were used without any further modification. The maximum
monolayer adsorption capacity was computed with Langmuir isotherm
model, which showed a relatively high adsorption capacity of 300
mg.g
-1
for methylene blue. Also, Nasuha
et al.
[114] obtained a methylene blue
adsorption capacity of 147
mg.g
-1
for rejected tea, although the surface
area of the adsorbent was very low (4.2
m
2
.g
-1
). This relatively high dye
uptake was attributed to the presence of various functional groups on the
surface of the rejected tea. The shift of the hydroxyl, carbonyl and -C-C-
groups to lower frequencies and the disappearance of aromatic nitro com-
pounds, as exhibited in Table 5.21, demonstrated their involvement in the
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