polycyclic aromatic hydrocarbons in it. In China, around ten dyeing factories were
found to contain a significant polycyclic aromatic hydrocarbons level in its sludge
(Ning et al. 2014). It has been reported that in most of the industrial areas of world,
thousands of gallons of exploited motor oil including polycyclic aromatic hydrocarbons s are disposed untreated into soil (Irland et al. 1995). Most of the polycyclic
aromatic hydrocarbons have high stability and lipid solubility causing its accumulation in organism including mankind above all. The US Environmental Protection
Agency has included 16 polycyclic aromatic hydrocarbons into its most toxic
organic pollutants (Callahan et al. 1979). In eastern Asia, the concentration of
polycyclic aromatic hydrocarbons in soil ranges between 10 and 20 g kg
À1 with
highest proportion of 102 and 104 g kg
À1 in critical areas. It was concluded through
aerial examination of polycyclic aromatic hydrocarbon content in various cities of
United States that highest level of polycyclic aromatic hydrocarbons occurs during
the winter months (Sawicki et al. 1960).
Nitrogen- and oxygen-containing derivatives of polycyclic aromatic hydrocarbons are reportedly mutagenic, carcinogenic, and estrogenic (Lundstedt et al. 2007;
Dipple 1985). Derivatives of polycyclic aromatic hydrocarbons are generally formed
through homogeneous/heterogeneous photooxidation of parent polycyclic aromatic
hydrocarbons with natural oxidants and photodecomposition along with heat
exchange (Cochran et al. 2016). It is noteworthy that few of the derivatives of
polycyclic aromatic hydrocarbons are more poisonous and possess greater danger
to human health (EHC 2003).
In view of the above facts, a simple and economic strategy is needed to be
developed for the removal of polycyclic aromatic hydrocarbons. One of the oldest
effective methods of polycyclic aromatic hydrocarbons removal is bioremediation,
where variety of microorganisms have been categorized and injected in affected soils
(Kuppusamy et al. 2017). However, bioremediation is linked to certain limitations,
such as lack of environmental support to microbial growth, little bioavailability of
desired contaminants, involvement of various unwanted contaminants, and time
consumption (Liu et al. 2017). Other well-known techniques include photo and
chemical oxidation, adsorption, filtration, volatilization, discharge, and
microorganism-based degradation (Wild and Jones 1995). Recently, heterogeneous
catalysis has exhibited successful performance in wastewater treatment owing to its
high activity and cheapness and use natural light source like sunlight (Saad Hassan
et al. 2015). Semiconductor involved in photocatalysis causes the excitation of
electron from lower energy level to higher energy level, creating a vacancy behind.
In the presence of a source of light, oxidation and reduction can take place
resulting into degradation of contaminants in relatively short time (Zhang et al.
2008). Most of such nanomaterials exhibit outstanding properties such as mechanical strength along with chemical confrontation for a broad range of pH. However,
their hydrophobic nature limits their use in water purification techniques. In recent
times, modification of nanomaterials through their surface functionalization has
gained a great attention worldwide owing to its simple fabrication, hydrophilicity,
and better dispersion (Hebbar et al. 2016; Pereira et al. 2015).
5 Degradation of Polycyclic Aromatic Hydrocarbons by Functionalized Nanomaterials
133
found to contain a significant polycyclic aromatic hydrocarbons level in its sludge
(Ning et al. 2014). It has been reported that in most of the industrial areas of world,
thousands of gallons of exploited motor oil including polycyclic aromatic hydrocarbons s are disposed untreated into soil (Irland et al. 1995). Most of the polycyclic
aromatic hydrocarbons have high stability and lipid solubility causing its accumulation in organism including mankind above all. The US Environmental Protection
Agency has included 16 polycyclic aromatic hydrocarbons into its most toxic
organic pollutants (Callahan et al. 1979). In eastern Asia, the concentration of
polycyclic aromatic hydrocarbons in soil ranges between 10 and 20 g kg
À1 with
highest proportion of 102 and 104 g kg
À1 in critical areas. It was concluded through
aerial examination of polycyclic aromatic hydrocarbon content in various cities of
United States that highest level of polycyclic aromatic hydrocarbons occurs during
the winter months (Sawicki et al. 1960).
Nitrogen- and oxygen-containing derivatives of polycyclic aromatic hydrocarbons are reportedly mutagenic, carcinogenic, and estrogenic (Lundstedt et al. 2007;
Dipple 1985). Derivatives of polycyclic aromatic hydrocarbons are generally formed
through homogeneous/heterogeneous photooxidation of parent polycyclic aromatic
hydrocarbons with natural oxidants and photodecomposition along with heat
exchange (Cochran et al. 2016). It is noteworthy that few of the derivatives of
polycyclic aromatic hydrocarbons are more poisonous and possess greater danger
to human health (EHC 2003).
In view of the above facts, a simple and economic strategy is needed to be
developed for the removal of polycyclic aromatic hydrocarbons. One of the oldest
effective methods of polycyclic aromatic hydrocarbons removal is bioremediation,
where variety of microorganisms have been categorized and injected in affected soils
(Kuppusamy et al. 2017). However, bioremediation is linked to certain limitations,
such as lack of environmental support to microbial growth, little bioavailability of
desired contaminants, involvement of various unwanted contaminants, and time
consumption (Liu et al. 2017). Other well-known techniques include photo and
chemical oxidation, adsorption, filtration, volatilization, discharge, and
microorganism-based degradation (Wild and Jones 1995). Recently, heterogeneous
catalysis has exhibited successful performance in wastewater treatment owing to its
high activity and cheapness and use natural light source like sunlight (Saad Hassan
et al. 2015). Semiconductor involved in photocatalysis causes the excitation of
electron from lower energy level to higher energy level, creating a vacancy behind.
In the presence of a source of light, oxidation and reduction can take place
resulting into degradation of contaminants in relatively short time (Zhang et al.
2008). Most of such nanomaterials exhibit outstanding properties such as mechanical strength along with chemical confrontation for a broad range of pH. However,
their hydrophobic nature limits their use in water purification techniques. In recent
times, modification of nanomaterials through their surface functionalization has
gained a great attention worldwide owing to its simple fabrication, hydrophilicity,
and better dispersion (Hebbar et al. 2016; Pereira et al. 2015).
5 Degradation of Polycyclic Aromatic Hydrocarbons by Functionalized Nanomaterials
133