278
The values for the coefficients of correlation for pseudo-first-order model are
satisfactory but do not necessarily mean that the kinetic reaction takes place by this
mechanism. But for the reaction of pseudo-second order, excellent results for the
correlation coefficients are obtained. All coefficients have a value above 0.99, indicating that Cr(VI) ion adsorption on clayey diatomite followed pseudo-secondorder kinetic model.
Fig. 9.12 Kinetic adsorption of pseudo-first-order model for the system Cr(VI) ions-clayey
diatomite
0
500
1000
1500
2000
0
50
100
150
200
t/q
t
t [min]
γo = 0.3 mg/l
γo = 0.4 mg/l
γo = 0.5 mg/l
γo = 0.6 mg/l
Fig. 9.13 Kinetic
adsorption of pseudosecond- order model for the
system Cr(VI)
ions-diatomite
Table 9.4 Parameters derived from pseudo-first- and pseudo-second-order kinetic models
Cr(VI)
Pseudo-first order
Pseudo-second order
γ 0
[mg/l]
q e,exp
[mg/g]
q e,cal.
[mg/g]
k 1
[min
−1
] R
2
q e,cal.
[mg/g]
k 2 [g/
mg∙min]
h [mg/
g∙min]
R
2
0.3
0.116
0.077
0.159
0.928 0.116
10.6339
0.145
1.000
0.4
0.152
0.058
0.014
0.777 0.151
1.1223
0.026
0.996
0.5
0.188
0.171
0.021
0.996 0.221
0.1487
0.007
0.994
0.6
0.196
0.092
0.019
0.893 0.199
0.490
0.030
0.997
H. Memedi et al.