A new graphene oxide
(GO) nanocomposite that contains chitosan,
a biological polymer, combined with a magnetic nanoparticle inorganic
material (Fe3O4) was successfully prepared and
applied for the adsorption of Pb(II) from aqueous solutions. The structural
and morphological properties of the GO/Fe3O4/CS (GFC) nanocomposites were characterized by X-ray diffraction,
scanning electron microscopy, and energy-dispersive X-ray spectroscopy.
Influent factors for Pb(II) adsorption, including the contacting time,
pH of the working medium, working temperature, and adsorbent dosage
on the adsorption efficiency, have been optimized. Under optimized
conditions, the adsorption isotherm results indicated that the Langmuir
model provided a better description for the adsorption of Pb(II) onto
the GFC nanosorbent than the Freundlich model. The maximum adsorption
capacity (q
max) was 63.45 mg g–1. The pseudo-second-order kinetic model (R
2 = 0.999) was fitted with the experimental results, implying that
the adsorption of Pb(II) onto GFC is a chemical process. The thermodynamic
studies demonstrated the exothermic nature of the adsorption process.
Another advantage of the GFC nanosorbent for Pb(II) removal is its
capability to be easily recovered under the use of an external magnet
and subsequently regenerated. Our work demonstrated that the removal
efficiency was stable after several regeneration cycles (i.e., approximately
12% reduction after four successive adsorption–desorption cycles),
implying that the GFC nanosorbent exhibits satisfactory regeneration
performance. Therefore, with high removal efficiency, high adsorption
capacity, and stable reusability, the GFC nanocomposite is a remarkable
application potential adsorbent for the in situ treatment of Pb(II)
ion-containing aqueous solutions.