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218
MIHAELA-CLAUDIA TERTIŞ, FLORINA IONESCU, MARIA JITARU
Table 2. The equations parameters of Langmuir, Freundlich and Tempkin
adsorption isotherm for nitrophenolic compounds at 25 o C.
Nitro
phenol q max
(mg g -1 )
Langmuir parameters
b
(L mg -1 )
Freundlich
parameters
K
F
1/n
Tempkin
parameters
k 1
(L mg -1 )
(mg g -1 )
(L mg -1 ) 1/n
4-NP 277.77 86.44 2.04 1.52 33.6 0.59
2,6-DNP 41.15 0.63 2.01 2.30 5.4 36.39
lnqe
6
5
4
3
2
1
(a)
y = 0.7144x + 1.5204
R 2 = 0.9901
0
-1 0 1 2 3 4 5 6 7
lnCe
y = 0.6988x + 2.2994
R 2 = 0.9865
(b)
-2
k 2
-5 -4 -3 -2 -1
0
0
-1
1 2 3
Figure 3. Linear form of Freundlich adsorption isotherm for: (a) 4-NP and (b) 2, 6-DNP
adsorption on granular activated carbon type NORIT GAC1240W, at 25 o C.
q e (m g 4-N P g -1 N OR IT GA C
1240W )
250
200
150
100
50
(a)
y = 33.607x - 17.826
R 2 = 0.8026
0
-1 0
-50
1 2 3 4 5 6 7
lnCe
lnq e
lnCe
(b)
y = 5.4003x + 19.41
R 2 = 0.8766
0
-5 -4 -3 -2 -1 0 1 2 3
-10
Figure 4. Linear form of Tempkin adsorption isotherm for: (a) 4-NP and (b) 2, 6-DNP
adsorption on granular activated carbon type NORIT GAC1240W, at 25 o C.
q e (m g 2,6-D N P g -1 N OR IT
GA C 1240W )
5
4
3
2
1
lnC e
40
30
20
10