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the process of adsorption depends on the physical properties of adsorbent, which in
turn have a major impact on the mechanism of adsorption, chemical properties of
the system adsorbate-adsorbent, equilibrium behavior, and working conditions in
the investigated system.
9.3.9.1 Kinetic Models
Experimental data are analyzed using several kinetic models to determine which
model equation describes the kinetic process: pseudo-first- and pseudo-secondorder models and model of Elovic.
Model for reaction of pseudo-first order:
ln
ln
q q
q k t
e
t
e
1
(9.7)
k 1 is constant speed of reaction of pseudo-first order [min
−1
].
• Model reaction of pseudo-second order of reaction:
t
q
t
q k q
t
e
e
1
2
2
(9.8)
k 2 is equilibrium constant of the reaction speed of the pseudo-second order [g/
mg∙min]; k 2 q e
2
or h [mg/g∙min] is the initial speed of adsorption.
• Model of Elovic:
q
t
t
1
1
E
DE E
ln
ln
(9.9)
α constant (mg/g∙min) is designated by q t graph regarding lnt, and constant β (g/
mg) of the graph is relative to q t , lnt.
9.3.9.2 Determination of the Adsorption Kinetic Using
Pseudo-First- Order Kinetic Model
Obtained experimental data for system Cr(VI)-clayey diatomite analyzed by
pseudo-first-order reaction are shown in Fig. 9.12.
9.3.9.3 Determination of the Adsorption Kinetic Using
Pseudo-Second- Order Kinetic Model
The obtained experimental data for the system Cr(VI) ions-diatomite analyzed
using the pseudo-first-order reaction are shown in Fig.  9.13. Pseudo-first- and
pseudo-second-order adsorption parameters are shown in Table 9.4.
9 Removal of Chromium(VI) from Aqueous Solution by Clayey Diatomite: Kinetic…