Adsorption of metal ions by microwave assisted grafting of
cross‐linked chitosan beads. Equilibrium, isotherm,
thermodynamic and desorption studies
E. Igberase | P. Osifo | A. Ofomaja
Department of Chemical Engineering,
Vaal University of Technology,
Vanderbijlpark 1900, South Africa
E Igberase, Department of Chemical
Engineering, Vaal University of
Technology, Private Mail Bag X021,
Vanderbijlpark 1900, South Africa.
Chemical modification of chitosan has become increasingly essential due to
chitosan versatility that enables the material to be easily modified in a way of
increasing its properties in adsorption processes. In this investigation, chitosan
solution was cross‐linked with glutaraldehyde the cross‐linked solution was
used in producing the beads and thereafter grafted with ethylene acrylic acid.
The chemical functionalities of the beads were obtained by Fourier transform
infrared spectroscopy (FTIR), Scanning electron microscope (SEM), X‐ray dif-
fraction (XRD) and Thermogravimetric analysis (TGA). Adsorption of Pb
ions from single component aqueous mixture
by grafted cross‐linked chitosan beads (GXXB) was studied as a function of pH,
temperature, initial concentration, contact time, agitation speed and ionic
strength. Equilibrium data was obtained from the adsorption experiment, the
data were applied in isotherm, thermodynamics and kinetic studies. The Lang-
muir, Temkin and Dubinin‐kaganer‐Radushkevich (DKR) model were success-
ful in describing the isotherm data for the considered metal ions while the
Freundlich model was not efficient in describing the experimental data.
Pseudo‐second order and intra‐particle model described the kinetic data quite
well. Thermodynamic parameters such as Gibb's free energy change (G
enthalpy change (H
) and entropy change (S
) were calculated and the results
showed the adsorption of Pb
GXXB is spontaneous and endothermic in nature. Regeneration of the used
adsorbent was effective for the studied metal ions.
chemical modification, kinetics, maximum adsorption capacity, regeneration, thermodynamics
1 | INTRODUCTION
Each year, large amount of heavy metals ions such as
and others enter our
food chain through the discharge of wastewater into
water resources, particularly in developing countries.
The major source of these metal ions is the ever‐
increasing industries including chemical, electroplating,
leather, tannery, galvanizing, mining, pharmaceutical,
pigment and dye industries,
which results in the
global use of these metal ions. Heavy metal ions are un‐
biodegradable and toxic contaminant which is hazardous
to human, animal, aquatic life and environment at large.
Several diseases such as lung and kidney problem,
Received: 7 July 2017 Revised: 14 September 2017 Accepted: 15 September 2017
Appl Organometal Chem. 2018;32:e4131.
Copyright © 2017 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/aoc 1of14