Table 3 Parameters of adsorption kinetic of Fe
3+
onto apricot seed shells
Parameters
Values
q
exp,
mg/g
44
Pseudo-first-order
k
1
, min
-1
6.50·10
-3
q
e
, mg/g
23
R
2
0,9762
Pseudo-second-order
k
2
, mg/g min
6.90·10
-4
q
e
, mg/g
46
R
2
0,9883
Intraparticle diffusion
k
2
, (mg/g min
1/2
)
0, 213
C
8,2
R
2
0,8899
a
b
c
Figure 5. Kinetic models of iron ions adsorption by apricot seed shells: pseudo-
first-order (a), pseudo-second-order (b) and intraparticle diffusion (c)
The calculated value of sorption capacity is twice less than the experimental one.
The value of R
2
for the pseudo-second-order models is greater than for pseudo-first-
order and close to 1, testifying about applicability of pseudo-second-order model of the
processes of the adsorption of Fe
3+
onto plant material. The lower value of R
2
for the
intraparticle diffusion models indicate the adsorption of Fe
3+
onto studied materials is
a multi-step process, including dye adsorption on the surface and diffusion into the
interior.
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