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Abstract
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Herein, a novel, efficient and inexpensive adsorbent based
on graphene quantum dots (GQDs) coated on quartz sand
(GQDs|QS) for removal of Hg21 and Pb21 from aqueous solutions
was reported. The GQDs|QS was characterized by
scanning electron microscopy, energy-dispersive X-ray spectroscopy,
Fourier transform infrared spectroscopy, and X-ray
powder diffraction techniques. To optimize operation parameters
and study removal efficiency of the prepared adsorbent,
a batch removal system followed by anodic stripping voltammetry
technique was used during the experiments. The maximum
adsorption capacity of GQDs|QS for Hg21 and Pb21
were calculated 24.65 and 24.92 mg g21, respectively, which
reveal more improved adsorption capacitance of the
GQDs|QS in comparison with nontreated QS. According to
experimental results, adsorption of Hg21 and Pb21 on the
developed adsorbent follows pseudo-second order kinetic
model. In addition, equilibrium experimental data appropriately
fit with the Langmuir isotherm (R2>0.99). It was
found that the stability and removal performance of the
GQDs|QS strongly depend to the particle size of GQDs. Due
to low cost, stability and effectiveness of the GQDs|QS, it
could be used as a suitable choice for water treatment in
industrial scale.
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