279
9.3.9.4 Determination of the Adsorption Kinetic Using Kinetic Model
of Elovic
Obtained experimental data for the system Cr(VI) ions-diatomite analyzed using the
kinetic model of Elovic are shown in Fig. 9.14. Kinetic parameters for the model of
Elovic are shown in Table 9.5.
The high values of the coefficients of correlation of the Elovic model point out
that the adsorption of Cr(VI) ions using diatomite as adsorbent is a reversible
process.
9.4 Conclusions
The adsorption of Cr(VI) ions onto a clayey diatomite was shown to occur very
efficiently with 96.7%. During the experiments the effect of operating parameters,
such as amount of adsorbent (0.5–5.5 g/l), initial adsorbate concentration (0.3, 0.4,
0.5, and 0.6 mg/l), and time of adsorption (5–180 min) at pH of the solution 3, was
examined. It was found that 2.5 g/l is optimal adsorbent dosage for maximal removal
of Cr(VI) ions. The percentage of removal decreases from 96.7% to 81.7% as initial
metal ion concentration increases from 0.3 to 0.6 mg/l, respectively. 45–60 min of
adsorption was sufficient time to achieve equilibrium for initial concentrations of
0
0.05
0.1
0.15
0.2
0.25
0
2
4
6
q
t [mg/g]
ln t
γo = 0.3 mg/l
γo = 0.4 mg/l
γo = 0.5 mg/l
γo = 0.6 mg/l
Fig. 9.14 Kinetic model
of Elovic for the system
Cr(VI) ions-diatomite
Table 9.5 Parameters derived from kinetic model of Elovic
Cr(VI)
Model of Elovic
γ 0 [mg/l]
α [mg/g∙min]
β [mg/g]
R
2
0.3
32.8 ∙ 10
4
200.00
0.734
0.4
13.16
83.33
0.939
0.5
0.1143
22.73
0.983
0.6
1.4740
50.00
0.989
9 Removal of Chromium(VI) from Aqueous Solution by Clayey Diatomite: Kinetic…