using X-ray diffraction. The diffraction peak of graphene is linked to the A–B stacking
order, which correlated with the [002] reflection (Machado and Serp 2012). The [002]
reflection occurred at 2θ % 26
for pristine graphite, and after oxidation, the layers
were shifted to 2θ %11
(Machado and Serp 2012). The number of layers is evaluated
using the line broadening by the Lorentzian fitting of the [002] reflection and the
Scherrer equation (Rao et al. 2009). Currently, atomic force microscopy is among the
most effective technique used to detect few-layer and single-layer crystals (Blake et al.
2007). Therefore, the atomic force microscopy can measure elastic, magnetic, electrical, and mechanical properties of graphene (Singh et al. 2011). The scanning electron
microscopy images are used to determine the presence of defects and morphology of
graphene, as well as acquiring atomically resolved images of graphene sheets
(Machado and Serp 2012).
1.6.5 Adsorption Mechanism of Graphene
The adsorption properties of graphene are influenced by surface properties, such as
distribution, surface area, and pore size (Yusuf et al. 2015). Thus, the surface area
largely influences the adsorption of adsorbate on the adsorbent since the surface area
per unit volume of the adsorbate determines the adsorption ability of the adsorbent
(Yusuf et al. 2015). During the adsorption process, a larger surface induces a large
surface area of active sites exposed to the adsorbate (Yusuf et al. 2015). Hence, an
adsorbent with a small grain size distribution and high porosity increases the
adsorption ability and the total surface area (Mohanty et al. 2008). However,
graphene exhibited no porosity and an ultrahigh specific surface. The adsorption
capacity of graphene can be enhanced by combining with other porous materials
(Zhang et al. 2011a).
1.7 Progress on Graphene and Semiconductor Composites
There has been much interest in the fabrication of graphene/semiconductor composites due to the variety of functional semiconductor nanoparticles (Lü et al. 2012).
During the pollutant removal process, graphene can often tune the properties of
semiconductors. In particular, magnetic Fe 3 O 4 nanoparticles have been used as
magnetic separation in large-scale industrial application and to address several
problems related to gravitational separation, filtration, and centrifugation of
graphene. Coupling graphene with a semiconductor is an attractive material for
photocatalytic applications since graphene has a zero band gap, high conductivity
of electron in storage, and migration of electrons. The nanoparticles on the graphene
surface prevent the aggregation of GR sheets to some degree in the composites,
which further increases the exposed area for the elimination of pollutants from water/
wastewater resources.
1 Nanotechnology for Water and Wastewater Treatment Using Graphene. . .
13
order, which correlated with the [002] reflection (Machado and Serp 2012). The [002]
reflection occurred at 2θ % 26
for pristine graphite, and after oxidation, the layers
were shifted to 2θ %11
(Machado and Serp 2012). The number of layers is evaluated
using the line broadening by the Lorentzian fitting of the [002] reflection and the
Scherrer equation (Rao et al. 2009). Currently, atomic force microscopy is among the
most effective technique used to detect few-layer and single-layer crystals (Blake et al.
2007). Therefore, the atomic force microscopy can measure elastic, magnetic, electrical, and mechanical properties of graphene (Singh et al. 2011). The scanning electron
microscopy images are used to determine the presence of defects and morphology of
graphene, as well as acquiring atomically resolved images of graphene sheets
(Machado and Serp 2012).
1.6.5 Adsorption Mechanism of Graphene
The adsorption properties of graphene are influenced by surface properties, such as
distribution, surface area, and pore size (Yusuf et al. 2015). Thus, the surface area
largely influences the adsorption of adsorbate on the adsorbent since the surface area
per unit volume of the adsorbate determines the adsorption ability of the adsorbent
(Yusuf et al. 2015). During the adsorption process, a larger surface induces a large
surface area of active sites exposed to the adsorbate (Yusuf et al. 2015). Hence, an
adsorbent with a small grain size distribution and high porosity increases the
adsorption ability and the total surface area (Mohanty et al. 2008). However,
graphene exhibited no porosity and an ultrahigh specific surface. The adsorption
capacity of graphene can be enhanced by combining with other porous materials
(Zhang et al. 2011a).
1.7 Progress on Graphene and Semiconductor Composites
There has been much interest in the fabrication of graphene/semiconductor composites due to the variety of functional semiconductor nanoparticles (Lü et al. 2012).
During the pollutant removal process, graphene can often tune the properties of
semiconductors. In particular, magnetic Fe 3 O 4 nanoparticles have been used as
magnetic separation in large-scale industrial application and to address several
problems related to gravitational separation, filtration, and centrifugation of
graphene. Coupling graphene with a semiconductor is an attractive material for
photocatalytic applications since graphene has a zero band gap, high conductivity
of electron in storage, and migration of electrons. The nanoparticles on the graphene
surface prevent the aggregation of GR sheets to some degree in the composites,
which further increases the exposed area for the elimination of pollutants from water/
wastewater resources.
1 Nanotechnology for Water and Wastewater Treatment Using Graphene. . .
13