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Abstract
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This study describes the use of a ternary composite of Fe3O4,
chitosan and graphene quantum dots (
Fe3O4/GQDs-Chit) as
an efficient magnetic adsorbent for the removal of Pb2+
from aqueous solutions. A number of methods were employed to
describe the prepared adsorbent including scanning and transmission electron microscopy, vibrating sample magnetometer,
Fourier-transform infrared spectroscopy and X-ray diffraction. Removal experiments were conducted in a batch system to
optimize adsorbent amount, initial Pb2+
concentration, solution pH, and contact time. To explore the equilibrium isotherm
and calculate the isotherm constants, Langmuir and Freundlich adsorption models were used. Accordingly, the Fe3O4/
GQDs-
Chit were successful in removing Pb2+
up to 117.65 mg g−
1 from water, with good agreement to Langmuir isotherm model
(R2 = 0.9957). The adsorption kinetic was well fitted (R2 > 0.9940) with pseudo-second-order model indicating chemical
adsorption as the rate-limiting step in the adsorption process. Furthermore, thermodynamic parameters revealed that the
adsorption of Pb2+
on the Fe3O4/
GQDs-Chit was exothermic and spontaneous. As evidenced by regeneration experiments,
Fe3O4/
GQDs-Chit were a highly stable and reproducible adsorbent, which can function as an efficient adsorbent in water
treatment.
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