Environmental Engineering Reference
In-Depth Information
resulting nanocomposite is not merely the sum of the individual compo-
nents, but instead a new material with new functionalities and properties
[150]. The NMO/polymer anchored on graphene two-dimensional struc-
tures not only arrests the agglomeration and restacking but also increases
the available surface area of the graphene sheet alone, leading to high
adsorption activity. The incorporated material also provides high selectivity
and strong binding of the desired contaminant depending on its structure,
size and crystallinity. In contrast, the graphenic materials provide chemi-
cal functionality and compatibility to allow easy processing of the depos-
ited NMO/polymer in the composite. The ultimate goal is to maximize the
practical use of the combined advantages of both the components as active
materials for improving the adsorption performance and potential.
Wa n g
et al.
[125] synthesized a graphene-based magnetite nanocom-
posite (G/Fe
3
O
4
) by
in situ
chemical co-precipitation of Fe
2+
and Fe
3+
in
alkaline solution in the presence of graphene and investigated its potential
as an adsorbent for the removal of Fuchsine dye from aqueous solution.
Adsorption isotherm and kinetics of Fuchsine on G/Fe
3
O
4
were studied
employing a batch experimental set-up. The effects of adsorbent dose
(0.2-0.5 g L
-1
), pH (3.0-10.0), and ionic strength (0-20% w/v NaCl) on the
removal efficiency of Fuchsine were investigated. The experimental data
obtained showed that the dye uptake process was very fast; about 96% of
the dye was adsorbed within 10 min and 99% of the dye was adsorbed
within 30 min. The amount of dye adsorbed increased with an increase in
pH from 3.0 to 5.5. Further increase in pH did not significantly change the
adsorption yield. Ionic strength did not show any direct influence on the
dye removal efficiency. The adsorption equilibrium data was best described
by the Langmuir isotherm model, with a maximum monolayer adsorption
capacity of 89.4 mg g
-1
. The adsorption process was found to be a pseudo-
second-order reaction. Furthermore, maximum desorption of 94% was
achieved at pH 2.0 using ethanol as the eluent. The adsorption capacity
of G/Fe
3
O
4
for Fuchsine did not show any significant decrease even after
five regenerations. Thus, G/Fe
3
O
4
proved to be a highly efficient adsorbent
for removal of color from dye-bearing wastewater. Graphene/magnetite
composites have also been prepared and successfully employed as adsor-
bent for the removal of Methylene Blue [126,127], Congo Red [127] and
Pararosaniline [128].
Wa n g
et al.
[129] synthesized a magnetic-sulfonic graphene nano-
composite (G-SO
3
H/Fe
3
O
4
) and explored it as adsorbent for the batch
removal of three cationic dyes: Safranine T, Neutral Red, Victoria Blue, and
three anionic dyes: Methyl Orange, Brilliant Yellow, Alizarin Red, from
their aqueous solutions. The G-SO
3
H/Fe
3
O
4
adsorbent showed excellent
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