Insight into adsorption equilibrium, kinetics and thermodynamics of lead onto alluvial soil|
Das, B.; Mondal, N. K.; Bhaumik, R. & Roy, P.
In the present study, adsorption of lead (II) ions
from aqueous solution by alluvial soil of Bhagirathi River
was investigated under batch mode. The influence of
solution pH, sorbent dose, initial lead (II) concentration,
contact time, stirring rate and temperature on the removal
process were investigated. The lead adsorption was favored
with maximum adsorption at pH 6.0. Sorption equilibrium
time was observed in 60 min. The equilibrium adsorption
data were analyzed by the Freundlich, Langmuir, Dubinin–
Radushkevich and Temkin adsorption isotherm models.
The kinetics of lead (II) ion was discussed by pseudo firstorder,
pseudo second-order, intra-particle diffusion, and
surface mass transfer models. It was shown that the
adsorption of lead ions could be described by the pseudo
second-order kinetic model. The activation energy of the
adsorption process (Ea) was found to be -38.33 kJ mol-1
using the Arrhenius equation, indicating exothermic nature
of lead adsorption onto alluvial soil. Thermodynamic
parameters, such as Gibbs free energy (ΔG0), the enthalpy
(ΔH0), and the entropy change of sorption (ΔS0) have also
been evaluated and it has been found that the adsorption
process was spontaneous, feasible, and exothermic in nature.
The results indicated that alluvial soil of Bhagirathi
River can be used as an effective and low cost adsorbent to
remove lead ions from aqueous solutions.
Activation energy; Adsorption isotherms and kinetics; Lead (II) ion; Surface mass transfer