where qt and qe are the amount of adsorbate at any time t
and at equilibrium time (mg g1) respectively, and k1 is the
rate constant of pseudo-first order adsorption (min1). k2 is
the rate constant of pseudo-second order adsorption
(g mg1 min1). In Eq. (7), a is the initial rate of adsorption
(g mg1 min1), b is the desorption constant (g mg1). kp is
the rate constant of intraparticle transport (mg g1 min0.5)
and c (mg g1).
3. Results and discussion
3.1. Adsorption isotherms and adsorption models
The equilibrium adsorption isotherm is fundamental for
describing the interactive behavior between adsorbate and
adsorbent. To achieve this goal, the adsorption data are analyzed
with Langmuir, Freundlich and Temkin isotherms.
The values of isotherms calculated by using different models
are listed in Table 1. From Table.1, the results show that:
(i) Langmuir isotherm is the best effective, according to the
correlation coefficient (r2). So the Langmuir model is
more appropriate to express the adsorption isotherm
of resin D301 absorbing glyphosate from the aqueous
solution.
(ii) From value of qmax in Langmuir isotherm, the maximum
capacity of adsorption increases with the temperature
increasing.