nature of the composite enabled easy separation of the contaminant-loaded adsorbent
from aqueous medium upon employment of an external magnetic field (Fig. 1.5).
Fe 3 O 4 /graphene oxide magnetic nanocomposite was functionalized by EDTA for the
purpose of adsorptive removal of Cu(II), Hg(II) and Pb(II) ions (Cui et al. 2015). The
adsorption capacity was found to be high, with obtained values of 301.2 mgg
À1 for
Cu(II), 268.4 mgg
À1 for Hg(II) and 508.4 mgg
À1 for Pb(II) after fitting into Temkin
and Freundlich isotherm models. Moreover, the adsorption process was found to be
pH dependent, with demonstration of the maximum removal efficiencies of 96.5% at
pH 5.1 for Cu(II), 95.1% at pH 4.1 for Hg(II) and 96.2% at pH 4.2 for Pb(II).
Wu et al. (2012) demonstrated a unique material composed of magnetic Fe 2 O 3
encapsulated in mesoporous carbon matrix for adsorptive capture and removal of
arsenic. This novel material produced 29.4 mgg
À1 of adsorption capacity with fast
adsorption pseudo-second-order rate. Moreover, it showed easy removal owing to its
magnetic nature, as well as potential to be reused. The processes of iron oxide
encapsulation and arsenic adsorption have been presented in Fig. 1.6. Other usages
of iron oxides have been as sand coated with iron oxide as well as zerovalent iron for
removal of arsenate and chromate (Mak et al. 2011); as a three-dimensional nanostructure comprising of carbon nanotube, graphene and iron oxide for adsorptive
removal of arsenic (Vadahanambi et al. 2013); as sewage sludge from municipality,
coated with iron oxide, for removal of Pb(II), Ni(II), Cd(II) and Cu(II) ions
(Phuengprasop et al. 2011); and polymer/iron oxide hybrid nanocomposites for
removal of chromate, arsenate, Cu(II), Cd(II) and Pb(II) ions from aqueous solutions
(Peter et al. 2017; Pan et al. 2010).
Several other metal oxides have been tested as potential decontaminating agents.
Among them, TiO 2 has gained some popularity owing to its performance efficiency.
For instance, Lee and Yang (2012) fabricated a hybrid composite constituting TiO 2
and graphene oxide. Upon using exfoliated graphene oxide nanosheets for
supporting TiO 2 nanoparticles, the formed hybrid presented a flower-like morphology. This nanohybrid adsorbent were used to adsorb Zn(II), Cd(II) and Pb(II) ions
Fig. 1.5 Easy separation of
contaminant-loaded
magnetic adsorbent from
aqueous medium upon
employment of an external
magnetic field. (Reprinted
with permission from
Chandra et al. (2010).
© 2010 American Chemical
Society)
10
K. Dutta
from aqueous medium upon employment of an external magnetic field (Fig. 1.5).
Fe 3 O 4 /graphene oxide magnetic nanocomposite was functionalized by EDTA for the
purpose of adsorptive removal of Cu(II), Hg(II) and Pb(II) ions (Cui et al. 2015). The
adsorption capacity was found to be high, with obtained values of 301.2 mgg
À1 for
Cu(II), 268.4 mgg
À1 for Hg(II) and 508.4 mgg
À1 for Pb(II) after fitting into Temkin
and Freundlich isotherm models. Moreover, the adsorption process was found to be
pH dependent, with demonstration of the maximum removal efficiencies of 96.5% at
pH 5.1 for Cu(II), 95.1% at pH 4.1 for Hg(II) and 96.2% at pH 4.2 for Pb(II).
Wu et al. (2012) demonstrated a unique material composed of magnetic Fe 2 O 3
encapsulated in mesoporous carbon matrix for adsorptive capture and removal of
arsenic. This novel material produced 29.4 mgg
À1 of adsorption capacity with fast
adsorption pseudo-second-order rate. Moreover, it showed easy removal owing to its
magnetic nature, as well as potential to be reused. The processes of iron oxide
encapsulation and arsenic adsorption have been presented in Fig. 1.6. Other usages
of iron oxides have been as sand coated with iron oxide as well as zerovalent iron for
removal of arsenate and chromate (Mak et al. 2011); as a three-dimensional nanostructure comprising of carbon nanotube, graphene and iron oxide for adsorptive
removal of arsenic (Vadahanambi et al. 2013); as sewage sludge from municipality,
coated with iron oxide, for removal of Pb(II), Ni(II), Cd(II) and Cu(II) ions
(Phuengprasop et al. 2011); and polymer/iron oxide hybrid nanocomposites for
removal of chromate, arsenate, Cu(II), Cd(II) and Pb(II) ions from aqueous solutions
(Peter et al. 2017; Pan et al. 2010).
Several other metal oxides have been tested as potential decontaminating agents.
Among them, TiO 2 has gained some popularity owing to its performance efficiency.
For instance, Lee and Yang (2012) fabricated a hybrid composite constituting TiO 2
and graphene oxide. Upon using exfoliated graphene oxide nanosheets for
supporting TiO 2 nanoparticles, the formed hybrid presented a flower-like morphology. This nanohybrid adsorbent were used to adsorb Zn(II), Cd(II) and Pb(II) ions
Fig. 1.5 Easy separation of
contaminant-loaded
magnetic adsorbent from
aqueous medium upon
employment of an external
magnetic field. (Reprinted
with permission from
Chandra et al. (2010).
© 2010 American Chemical
Society)
10
K. Dutta