have been used for the waste treatment (Raizada et al. 2017a, b; Raizada et al. 2019;
Jun et al. 2018; Mahto et al. 2015). Despite of their high activity, majority of
nanomaterials have certain limitations restricting utilization of 100% of their tendency. Firstly, recombination of the charge carriers has a negative impact on
photodegradation; secondly, potential effect on human health, reusability, and
restricted selectivity of nanocatalysts; and lastly, their reliability upon environmental
circumstances (Rani and Shanker 2018a, b).
So as to overcome these limitations, surface modification is believed to have an
important role in improving the overall activity of nanocatalysts (Yin et al. 2017a, b).
In recent times surface functionalization has drawn attention of researchers owing to
its potential benefits such as enhanced chemical reactivity, improved adsorption
capacity, low charge recombination, and better semiconducting properties (Rachna
and Shanker 2018, 2019a, b). List of some of the reported functionalized
nanomaterials is listed in Table 5.3.
Degradation of polycyclic aromatic hydrocarbons using some of the commonly
used functionalized nanomaterials is as described below.
5.6.1 Degradation Using Functionalized Carbon-Based
Nanomaterials
Carbon-based materials have some fascinating electronic and mechanical properties
like surface area and semiconducting behavior. Functionalization of these with other
acidic or basic groups can increase their activity in treatment of polluted water. The
decoration of carbon nanotubes with tungsten oxide significantly improved the
number of surface active sites and lowered the combination of charges. Consequently, the nanocomposite degraded the naphthalene into smaller and safer products by the attack of reactive species on the first and second position of naphthalene
(Rani and Shanker 2018). Overall degradation strategy has been given in Fig. 5.2.
Hybrid of carbon dots and fatty acid coated with magnetite nanoparticles were
successfully utilized for the photocatalytic mineralization of benzo[a]pyrene. The
nanocomposite was able to remove 93.9% of the benzo[a]pyrene from the environmental sample. The hydrophilic behavior of carbon dots enhanced the dispersibility
of the catalyst, and the hydrophobic interactions increased the removal benzo[a]
pyrene (Yang et al. 2019). Bai et al. 2017studied the photodegradation of some
polycyclic aromatic hydrocarbons using titanium dioxide-based graphene oxide
polymer. The nanocomposite possessed large surface area as well as high surface
energy sites including various defects, edges, and grooves. The contact of the
polycyclic aromatic hydrocarbons molecules with the nanocomposite was through
the pi-pi interaction. Structural similarity between the grapheme oxide and polycyclic aromatic hydrocarbons molecules caused their quick adsorption. Moreover, the
photogenerated holes, O 2
•À and •OH, formed the oxygenated and hydroxylated
5 Degradation of Polycyclic Aromatic Hydrocarbons by Functionalized Nanomaterials
143
Jun et al. 2018; Mahto et al. 2015). Despite of their high activity, majority of
nanomaterials have certain limitations restricting utilization of 100% of their tendency. Firstly, recombination of the charge carriers has a negative impact on
photodegradation; secondly, potential effect on human health, reusability, and
restricted selectivity of nanocatalysts; and lastly, their reliability upon environmental
circumstances (Rani and Shanker 2018a, b).
So as to overcome these limitations, surface modification is believed to have an
important role in improving the overall activity of nanocatalysts (Yin et al. 2017a, b).
In recent times surface functionalization has drawn attention of researchers owing to
its potential benefits such as enhanced chemical reactivity, improved adsorption
capacity, low charge recombination, and better semiconducting properties (Rachna
and Shanker 2018, 2019a, b). List of some of the reported functionalized
nanomaterials is listed in Table 5.3.
Degradation of polycyclic aromatic hydrocarbons using some of the commonly
used functionalized nanomaterials is as described below.
5.6.1 Degradation Using Functionalized Carbon-Based
Nanomaterials
Carbon-based materials have some fascinating electronic and mechanical properties
like surface area and semiconducting behavior. Functionalization of these with other
acidic or basic groups can increase their activity in treatment of polluted water. The
decoration of carbon nanotubes with tungsten oxide significantly improved the
number of surface active sites and lowered the combination of charges. Consequently, the nanocomposite degraded the naphthalene into smaller and safer products by the attack of reactive species on the first and second position of naphthalene
(Rani and Shanker 2018). Overall degradation strategy has been given in Fig. 5.2.
Hybrid of carbon dots and fatty acid coated with magnetite nanoparticles were
successfully utilized for the photocatalytic mineralization of benzo[a]pyrene. The
nanocomposite was able to remove 93.9% of the benzo[a]pyrene from the environmental sample. The hydrophilic behavior of carbon dots enhanced the dispersibility
of the catalyst, and the hydrophobic interactions increased the removal benzo[a]
pyrene (Yang et al. 2019). Bai et al. 2017studied the photodegradation of some
polycyclic aromatic hydrocarbons using titanium dioxide-based graphene oxide
polymer. The nanocomposite possessed large surface area as well as high surface
energy sites including various defects, edges, and grooves. The contact of the
polycyclic aromatic hydrocarbons molecules with the nanocomposite was through
the pi-pi interaction. Structural similarity between the grapheme oxide and polycyclic aromatic hydrocarbons molecules caused their quick adsorption. Moreover, the
photogenerated holes, O 2
•À and •OH, formed the oxygenated and hydroxylated
5 Degradation of Polycyclic Aromatic Hydrocarbons by Functionalized Nanomaterials
143