Environmental Engineering Reference
In-Depth Information
Table 11.3
Various isotherm constants for the removal of Azo Dyes at different
temperatures.
Langm
uir Constants
Adsorption System
q
o
× 10
-4
(mol g
-1
)
b × 10
3
(L mol
-1
)
30°C
40°C
50°C
30°C
40°C
50°C
Amaranth - Hen Feather
2.44
2.49
2.50
1.25
1.73
2.19
Tartrazine - Hen Feather
1.20
1.32
1.45
179.14
188.98
220.24
Freundl
ich Constants
Adsorption System
n
K
F
30°C
40°C
30°C
40°C
30°C
40°C
Amaranth - Hen Feather
0.13
0.15
0.15
0.999
0.999
0.999
Tartrazine - Hen Feather
4.32
3.99
4.03
0.001
0.002
0.002
Tempk
in Constants
Adsorption System
k
1
× 10
-5
(L.mol
-1
)
k
2
× 10
4
30°C
40°C
50°C
30°C
40°C
50°C
Amaranth - Hen Feather
5.00
5.00
6.00
16.275
16.275
11.662
Tartrazine - Hen Feather
10
20
20
17.848
9.873
16.272
D-R
Constants
Adsorbent
β × 10
-9
(mol
2
J
-2
)
E(kJ mol
-1
)
30°C
40°C
50°C
30°C
40°C
50°C
Amaranth - Hen Feather
6
5
4
9.13
10.00
11.18
Tartrazine - Hen Feather
2
2
2
15.81
15.81
15.81
11.5.3.3
Tempkin Isotherm Model
The graphical presentations for the Tempkin adsorption model of both
the adsorption systems at 30, 40 and 50 C are presented in Figures 11.12
to 11.13. The straight lines obtained clearly indicate that in both of the
cases the regression coefficient values close to unity are obtained. This
indicates that by and large adsorption of Azo dyes follows Tempkin
adsorption isotherm and uniform distribution of binding energy
takes place due to interaction of the dye molecules. The straight lines
obtained from the graphs are also helpful in determining the Tempkin
isotherm constants and Tempkin isotherm energy constants for both
the adsorption systems. The values of these constants are presented in
Table 11.3.
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