There are different varieties of nanomaterials applied for eliminating contaminants
from environmental matrices (Goutam et al. 2018). These nanomaterials can be
classified into nanotubes, nanofibers, nanoshells, nanoclusters, and nanocomposites
depending on their shape, size, structure, and composition. These nanomaterials have
demonstrated successful removal of hazardous pollutants from ground/surface water,
soil, and sediments. For instance, carbon nanotubes are reported to successfully
remove organic contaminants and metal ions from wastewater through adsorption
process (Hadavifar et al. 2014). Nanofibers have also shown their potency in removing
toxic compounds. Nylon 6 electrospun nanofibers not only remove estrogens from
aqueous solution but could be repeatedly used as long as seven times for removal
purposes (Qi et al. 2014). Titanate nanofibers also demonstrated 96% of phenol
degradation (Barrocas et al. 2017). Nanoshells referred to spherical particles having
a dielectric core and a thin metallic shell. Among nanoshells, Ag nanoshells have been
applied efficiently to catalyze the degradation of organic dyes in industrial effluents
(Vellaichamy and Periakaruppan 2016). Nanomaterials like nanoclusters and
nanocomposites have also shown their efficiency in environmental remediation. The
degradation efficiency of nonylphenol was found to be 96.2% within 120 min with
initial dosage of 0.4 g/L and 5 mM persulfate by nZVI nanocomposite (Hussain et al.
2017). Heavy metals like Ni, Zn, Pb, Cd, and Cr are also reported to be successfully
removed from water bodies using nanostructured graphite oxide and silica/graphite
oxide nanocomposite (Sarkar et al. 2018).
One of the significant advantages of using nanoparticles is that it can be used for
both in situ and ex situ remediation of harmful pollutants. In ex situ remediation, the
contaminated soil and water are brought to the treatment plants and treated with
nanoparticles methodically removing the toxic contaminants, whereas in in situ
treatment methods, nanoparticles are either directly injected to the contaminated
site or are introduced inside a permeable reactive barrier (PRB) where it successfully
treats the contaminant plume and removes it (Karn et al. 2009).
Nanoscale zerovalent iron (nZVI) has shown enormous potential in contaminant
reduction and can be successfully used in groundwater remediation either through
direct injection or through permeable reactive barriers (PRBs) (Singh et al. 1998; Oh
et al. 2001). A case study in Czech Republic reported that when nZVI was injected
into a metal fabrication industrial area contaminated with chlorinated ethylenes, it
showed 50% removal of the contaminant within 5–6 months (Lacina et al. 2015).
When an aquifer contaminated with trichloroethylene (TCE) was treated with nZVI,
it successfully removed 95.7% of TCE within 1 month without generating any
chlorinated intermediates. It was also found that nZVI can be reused several times
even after being aged for 5 months (Ahn et al. 2016).
Since the nanoparticles tend to agglomerate easily and oxidize fast, the surface of
nanoparticles can be coated with suitable stabilizers to increase its stability and
reduce agglomeration (Sakulchaicharoen et al. 2010). The surface coatings increase
the adsorbing capacity of nanoparticles decreasing their agglomeration. A report
showed that phosphate can be efficiently removed from water with humic acidcoated magnetite nanoparticles (Rashid et al. 2017). Titania-coated silica
nanoparticles degraded 93.29% of safranin-O dye from aqueous solution at optimal
7 Nano-bioremediation: An Innovative Remediation Technology for Treatment. . .
169
from environmental matrices (Goutam et al. 2018). These nanomaterials can be
classified into nanotubes, nanofibers, nanoshells, nanoclusters, and nanocomposites
depending on their shape, size, structure, and composition. These nanomaterials have
demonstrated successful removal of hazardous pollutants from ground/surface water,
soil, and sediments. For instance, carbon nanotubes are reported to successfully
remove organic contaminants and metal ions from wastewater through adsorption
process (Hadavifar et al. 2014). Nanofibers have also shown their potency in removing
toxic compounds. Nylon 6 electrospun nanofibers not only remove estrogens from
aqueous solution but could be repeatedly used as long as seven times for removal
purposes (Qi et al. 2014). Titanate nanofibers also demonstrated 96% of phenol
degradation (Barrocas et al. 2017). Nanoshells referred to spherical particles having
a dielectric core and a thin metallic shell. Among nanoshells, Ag nanoshells have been
applied efficiently to catalyze the degradation of organic dyes in industrial effluents
(Vellaichamy and Periakaruppan 2016). Nanomaterials like nanoclusters and
nanocomposites have also shown their efficiency in environmental remediation. The
degradation efficiency of nonylphenol was found to be 96.2% within 120 min with
initial dosage of 0.4 g/L and 5 mM persulfate by nZVI nanocomposite (Hussain et al.
2017). Heavy metals like Ni, Zn, Pb, Cd, and Cr are also reported to be successfully
removed from water bodies using nanostructured graphite oxide and silica/graphite
oxide nanocomposite (Sarkar et al. 2018).
One of the significant advantages of using nanoparticles is that it can be used for
both in situ and ex situ remediation of harmful pollutants. In ex situ remediation, the
contaminated soil and water are brought to the treatment plants and treated with
nanoparticles methodically removing the toxic contaminants, whereas in in situ
treatment methods, nanoparticles are either directly injected to the contaminated
site or are introduced inside a permeable reactive barrier (PRB) where it successfully
treats the contaminant plume and removes it (Karn et al. 2009).
Nanoscale zerovalent iron (nZVI) has shown enormous potential in contaminant
reduction and can be successfully used in groundwater remediation either through
direct injection or through permeable reactive barriers (PRBs) (Singh et al. 1998; Oh
et al. 2001). A case study in Czech Republic reported that when nZVI was injected
into a metal fabrication industrial area contaminated with chlorinated ethylenes, it
showed 50% removal of the contaminant within 5–6 months (Lacina et al. 2015).
When an aquifer contaminated with trichloroethylene (TCE) was treated with nZVI,
it successfully removed 95.7% of TCE within 1 month without generating any
chlorinated intermediates. It was also found that nZVI can be reused several times
even after being aged for 5 months (Ahn et al. 2016).
Since the nanoparticles tend to agglomerate easily and oxidize fast, the surface of
nanoparticles can be coated with suitable stabilizers to increase its stability and
reduce agglomeration (Sakulchaicharoen et al. 2010). The surface coatings increase
the adsorbing capacity of nanoparticles decreasing their agglomeration. A report
showed that phosphate can be efficiently removed from water with humic acidcoated magnetite nanoparticles (Rashid et al. 2017). Titania-coated silica
nanoparticles degraded 93.29% of safranin-O dye from aqueous solution at optimal
7 Nano-bioremediation: An Innovative Remediation Technology for Treatment. . .
169