composite was fabricated and used to remove Congo red and MB dyes from
wastewater media (Yao et al. 2012). The magnetic iron composite showed enhanced
adsorption capacities of 33.66 and 45.27 mg g
À1 for Congo red and MB dyes,
respectively. Thus, the composite had a high potential as an efficient adsorbent for
removing dyes from aqueous solution. A magnetic nanocomposite was reported to
have a high adsorption of fuchsine dye with about 96% of fuchsine dye adsorbed
(Wang et al. 2011a). This enhanced adsorption was due to the van der Waals
interactions between the honeycomb packed C atoms and the aromatic backbone
of fuchsine dye molecule, as well as the delocalized π-electron of the graphene sheet
and the π–π stacking interactions of the aromatic part of fuchsine dye. A magnetic
CoFe 2 O 4 /graphene composite was prepared by the hydrothermal treatment of exfoliated GR monolayers and inorganic salts (Li et al. 2011a). The as-prepared
nanocomposites showed adsorption high capacity (71.54 mg g
À1 ) to effectively
remove methyl orange (MO) dye. The SiO 2 /graphene composite, which was fabricated via a two-step technique, exhibited a high adsorption capacity (113.6 mg g
À1 )
toward Pb
2+ ion removal with reference to divalent ions, such as Cd
2+ , Ni
2+ , Co
2+ ,
Cu
2+ , and Cr
3+ (Hao et al. 2012). Nonetheless, the adsorption capacity of SiO 2 /
graphene composite was suppressed by the addition of KNO 3 . The effect of hydrothermal treatment period on the adsorption performance of TiO 2 /graphene composite
was investigated by Lee and Yang (2012) for the effective elimination of Pb
2+ , Cd
2+ ,
and Zn
2+ ions. They found that the exposure area of the composite was improved
from 88.97 to 132.74 m
2 g
À1 and the adsorption capacity from 45.0 Æ 3.8 to
65.6 Æ 2.7 mg g
À1 for Pb
2+ , 44.8 Æ 3.4 to 88.9 Æ 3.3 mg g
À1 for Zn
2+ , and
65.1 Æ 4.4 to 72.8 Æ 1.6 mg g
À1 for Cd
2+ upon prolonging the hydrothermal
treatment period from 6 to 12 h. A graphene nanosheet/Fe 3 O 4 composite, which
was synthesized by a facile one-step solvothermal route, showed fast adsorption
rates and excellent removal capacity of MB dye in water (Ai et al. 2011). This
enhancement was ascribed to the π–π interaction between the aromatic ring of
graphene and the MB dye, as well as electrostatic attraction between the cationic
MB and the negative surface of oxygen-containing groups. This study shows that the
as-synthesized composite could be used as efficient adsorbents for water purification. A detailed investigation of the δ-MnO 2 /graphene composite before and after
adsorption of lead and copper ions was performed by Ren et al. (2012), and they
found that the metal ions not only interpolate in the interlayer of δ-MnO 2 but also get
adsorbed on the composite surface. Moreover, the δ-MnO 2 /graphene composite
displayed high cycling, and the as-prepared composite can be utilized for at least
four times, without any significant loss in the adsorption capacity. The adsorption of
Ni ions on graphene/δ-MnO 2 composite showed enhanced adsorption capacity from
46.55 to 60.01 mg g
À1 , and this was 15 and 1.5 times higher than graphene
nanosheets and δ-MnO 2 , respectively (Ren et al. 2011).
A graphene-based Fe 3 O 4 magnetic nanoparticle was used as adsorbent for magnetic solid-phase extraction of prometon, atrazine, prometryn, and propazine (Zhao
et al. 2011). They established that the adsorbent was efficiently removed from
aqueous solution by an external magnet. A magnetic graphene/Fe 3 O 4
nanocomposite, which was fabricated by chemical precipitation method, had been
1 Nanotechnology for Water and Wastewater Treatment Using Graphene. . .
15
wastewater media (Yao et al. 2012). The magnetic iron composite showed enhanced
adsorption capacities of 33.66 and 45.27 mg g
À1 for Congo red and MB dyes,
respectively. Thus, the composite had a high potential as an efficient adsorbent for
removing dyes from aqueous solution. A magnetic nanocomposite was reported to
have a high adsorption of fuchsine dye with about 96% of fuchsine dye adsorbed
(Wang et al. 2011a). This enhanced adsorption was due to the van der Waals
interactions between the honeycomb packed C atoms and the aromatic backbone
of fuchsine dye molecule, as well as the delocalized π-electron of the graphene sheet
and the π–π stacking interactions of the aromatic part of fuchsine dye. A magnetic
CoFe 2 O 4 /graphene composite was prepared by the hydrothermal treatment of exfoliated GR monolayers and inorganic salts (Li et al. 2011a). The as-prepared
nanocomposites showed adsorption high capacity (71.54 mg g
À1 ) to effectively
remove methyl orange (MO) dye. The SiO 2 /graphene composite, which was fabricated via a two-step technique, exhibited a high adsorption capacity (113.6 mg g
À1 )
toward Pb
2+ ion removal with reference to divalent ions, such as Cd
2+ , Ni
2+ , Co
2+ ,
Cu
2+ , and Cr
3+ (Hao et al. 2012). Nonetheless, the adsorption capacity of SiO 2 /
graphene composite was suppressed by the addition of KNO 3 . The effect of hydrothermal treatment period on the adsorption performance of TiO 2 /graphene composite
was investigated by Lee and Yang (2012) for the effective elimination of Pb
2+ , Cd
2+ ,
and Zn
2+ ions. They found that the exposure area of the composite was improved
from 88.97 to 132.74 m
2 g
À1 and the adsorption capacity from 45.0 Æ 3.8 to
65.6 Æ 2.7 mg g
À1 for Pb
2+ , 44.8 Æ 3.4 to 88.9 Æ 3.3 mg g
À1 for Zn
2+ , and
65.1 Æ 4.4 to 72.8 Æ 1.6 mg g
À1 for Cd
2+ upon prolonging the hydrothermal
treatment period from 6 to 12 h. A graphene nanosheet/Fe 3 O 4 composite, which
was synthesized by a facile one-step solvothermal route, showed fast adsorption
rates and excellent removal capacity of MB dye in water (Ai et al. 2011). This
enhancement was ascribed to the π–π interaction between the aromatic ring of
graphene and the MB dye, as well as electrostatic attraction between the cationic
MB and the negative surface of oxygen-containing groups. This study shows that the
as-synthesized composite could be used as efficient adsorbents for water purification. A detailed investigation of the δ-MnO 2 /graphene composite before and after
adsorption of lead and copper ions was performed by Ren et al. (2012), and they
found that the metal ions not only interpolate in the interlayer of δ-MnO 2 but also get
adsorbed on the composite surface. Moreover, the δ-MnO 2 /graphene composite
displayed high cycling, and the as-prepared composite can be utilized for at least
four times, without any significant loss in the adsorption capacity. The adsorption of
Ni ions on graphene/δ-MnO 2 composite showed enhanced adsorption capacity from
46.55 to 60.01 mg g
À1 , and this was 15 and 1.5 times higher than graphene
nanosheets and δ-MnO 2 , respectively (Ren et al. 2011).
A graphene-based Fe 3 O 4 magnetic nanoparticle was used as adsorbent for magnetic solid-phase extraction of prometon, atrazine, prometryn, and propazine (Zhao
et al. 2011). They established that the adsorbent was efficiently removed from
aqueous solution by an external magnet. A magnetic graphene/Fe 3 O 4
nanocomposite, which was fabricated by chemical precipitation method, had been
1 Nanotechnology for Water and Wastewater Treatment Using Graphene. . .
15