solutions at initial MB concentration of 50 mg L
−1
and 250 mg L
−1
were fitted using the pseudo-first order and pseudo-second order
models.
The linearized forms of pseudo-first order (17) [31] and pseudo-second order (18) [32] kinetic models are shown below:
log(qe− qt) = log qe−
k1
2.303
t (17)
t
q1
=
1
kzq
2
e
+
1
qe
t (18)
where k1 (min
−1
) and k2 (mg g
−1
min−1
) are rate constants of
adsorption, qt (mg g
−1
) is the adsorption capacity at time t, qe
(mg g
−1
) is the equilibrium adsorption capacity.
All the kinetic parameters determined from the intercepts and
the slopes of respective plots (Fig. 8) are summarized in Table 3.
The adsorption process was best described by the pseudo-second
order kinetic model for both initial concentration of dye; in fact
this model shows a correlation coefficient (R
2
> 0.99) higher than
that of pseudo-first order model and the calculated values of the
adsorption capacities (qe) were very close to the experimental ones
(qexp).
The applicability of the pseudo-second order model suggests
that chemical reactions were responsible for the adsorption of MB
on keratin nanofiber membranes