carriers merge. Consequently, the accumulated electrons can confine the oxygen
present in solution and make different charged oxygen species to support the
polycyclic aromatic hydrocarbon removal (Yang et al. 2018). Composite of reduced
graphene oxide and iron oxides was used to remove naphthalene as well as
contrasted with the multi-walled carbon nanotubes/iron oxide composite. Higher
catalytic activity of graphene oxide/iron oxide composites was based upon its higher
electron donor-acceptor interaction. On the other hand, aggregation in cylindrical
multi-walled carbon nanotubes upon all random orientations resulted into congested
interstitial spaces, which resisted the entrance of aromatic compound (Yang and
Xing 2007; Yang et al. 2013a).
5.6.2 Degradation Using Functionalized Polymers
In recent times, coupling of semiconducting nanoparticles with the polymers are
fabricated in a lot worldwide due to its plenty functions. In a recent study, naphthalene was degraded under light source with the iron-doped zinc oxide and polyvinyl
alcohol nanofibers. Under ultraviolet light, 40 ppm of polycyclic aromatic hydrocarbons was kept for 4 h at neutral pH. Consequently, 96% degradation of naphthalene was achieved owing to the better semiconducting nature achieved upon doping
of Fe as well as formation of oxygen vacancies that can trap electrons and holes in
interstitial sites to prevent their recombination (Li et al. 2015a, b; Sekar et al. 2018).
Recently, the degradation of phenanthrene was utilized with the polydopamine
functionalized upon zero-valent iron and reduced graphene oxide. It successfully
degraded the 98.7% of phenanthrene at 7.74 pH via formation of SO 4•
À and HO •
radicals within the reaction mixture (Gu et al. 2018). A hybrid of zirconium oxideacetylacetonate derived from a gel was studied for the oxidative degradation of
phenanthrene in dark. The polymeric hybrid acted like a heterogeneous catalyst in
the absence of light, as the free radicals were generated via charge transfer between
metal and polymer. Moreover, the limitation of charge carriers’ recombination found
in various studies was overpowered here by the oxygen molecule scavenging the
electrons in conduction band. The presence of various radicals such as superoxide,
hydrogen peroxide, and hydroxyl initiated the oxidation and hence mineralization of
organic carbons. The identified end products here were alkanoic acids, alkanols, and
alkanes (Sannino et al. 2014).
5.6.3 Degradation Using Functionalized Metal
and Metal-Based Nanomaterials
Most of the work associated with polycyclic aromatic hydrocarbons degradation is
based upon the metals and metal-based nanomaterials. This is attributed to the vast
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Rachna et al.
present in solution and make different charged oxygen species to support the
polycyclic aromatic hydrocarbon removal (Yang et al. 2018). Composite of reduced
graphene oxide and iron oxides was used to remove naphthalene as well as
contrasted with the multi-walled carbon nanotubes/iron oxide composite. Higher
catalytic activity of graphene oxide/iron oxide composites was based upon its higher
electron donor-acceptor interaction. On the other hand, aggregation in cylindrical
multi-walled carbon nanotubes upon all random orientations resulted into congested
interstitial spaces, which resisted the entrance of aromatic compound (Yang and
Xing 2007; Yang et al. 2013a).
5.6.2 Degradation Using Functionalized Polymers
In recent times, coupling of semiconducting nanoparticles with the polymers are
fabricated in a lot worldwide due to its plenty functions. In a recent study, naphthalene was degraded under light source with the iron-doped zinc oxide and polyvinyl
alcohol nanofibers. Under ultraviolet light, 40 ppm of polycyclic aromatic hydrocarbons was kept for 4 h at neutral pH. Consequently, 96% degradation of naphthalene was achieved owing to the better semiconducting nature achieved upon doping
of Fe as well as formation of oxygen vacancies that can trap electrons and holes in
interstitial sites to prevent their recombination (Li et al. 2015a, b; Sekar et al. 2018).
Recently, the degradation of phenanthrene was utilized with the polydopamine
functionalized upon zero-valent iron and reduced graphene oxide. It successfully
degraded the 98.7% of phenanthrene at 7.74 pH via formation of SO 4•
À and HO •
radicals within the reaction mixture (Gu et al. 2018). A hybrid of zirconium oxideacetylacetonate derived from a gel was studied for the oxidative degradation of
phenanthrene in dark. The polymeric hybrid acted like a heterogeneous catalyst in
the absence of light, as the free radicals were generated via charge transfer between
metal and polymer. Moreover, the limitation of charge carriers’ recombination found
in various studies was overpowered here by the oxygen molecule scavenging the
electrons in conduction band. The presence of various radicals such as superoxide,
hydrogen peroxide, and hydroxyl initiated the oxidation and hence mineralization of
organic carbons. The identified end products here were alkanoic acids, alkanols, and
alkanes (Sannino et al. 2014).
5.6.3 Degradation Using Functionalized Metal
and Metal-Based Nanomaterials
Most of the work associated with polycyclic aromatic hydrocarbons degradation is
based upon the metals and metal-based nanomaterials. This is attributed to the vast
148
Rachna et al.