290
remaining are being released into atmosphere (0.1–1.5%), soils (8–28%), and water
bodies (0.4–7%) (Keller et al. 2013). Thus, despite multifaceted benefits for commercial purpose, their presence may cause hazardous biological effects in the
nature. The unique properties of these nanoparticles leading to detrimental effect in
environment mainly comprises of (i) high specific surface area, (ii) sufficient reactive sites on the surface, and (iii) their easy mobility (Wiesner et al. 2006). In this
direction, researchers have reported the interactions of nanoparticles with living
organisms and little, if any, information is available on the fate and behavior of these
nanoparticles within the environment and on human health (Handy et al. 2008).
Thus, to narrow the scope of this review, the present chapter aims to emphasize the
widespread contamination of the environment due to nanoparticles manufacturing
and waste disposal, and highlights the importance of econanotoxicity of engineered
nanomaterials to the waste management community.
11.2 Naturally Occurring and Engineered Nanoparticles
With increased anthropogenic activities along with the technological advancements,
nanoparticles generate enormous waste materials contaminating the biosphere and
pose serious ecological risks. However, nanoparticles still existed and leached into
the environment even before the formal emergence of the field of nanotechnology.
Naturally occurring nanoparticles are ubiquitous in nature. Several geological processes are known to produce natural nanoparticles such as in the form of combustion
by-product,
automobile
exhaust,
aerosols,
and
volcanoes
(Bystrzejewska-Piotrowska et al. 2009). Further, in biological processes, biomolecules like protein, nucleic acids, ATP, membranes, cells, organelles, etc. are directly
released into the environment from the organisms, leading to the formation of
nanoparticles as a result of degradation of biological matters (Bhatt and Tripathi
2011). However, many of these natural and incidental nanomaterials also have certain distinctive characteristics that cannot be denied from an environmental chemistry perspective (Bernhardt et al. 2010).
Unlike the naturally occurring nanoparticles that are formed heterogeneously
and disseminated in the environment, ENPs are mostly homogeneous in terms of
size, shape, and structure. The two approaches for the production of ENPs are topdown and bottom-up fabrication method (Bhatt and Tripathi 2011). In the first
method, lithographic techniques cut large materials into sizes less than 30 nm.
Alternatively, macromaterial are ground in a ball mill for producing NPs having size
less than 30 nm (Borm et al. 2006). In contrast, bottom-up synthesis process is a
more suitable method to convert extremely small molecules or atoms to nanometer
level (Christian et al. 2008). The diameter-tuning of nanoparticles is especially
imperative and is regulated with media in which they are synthesized. While temperature and reaction time are important within the realms of wet-phase synthesis
protocol, precursor concentration, as well as reaction temperature, controls the
diameter of ENPs in gas phase. Moreover, dispersing additives are used to stop
D. Kundu et al.
remaining are being released into atmosphere (0.1–1.5%), soils (8–28%), and water
bodies (0.4–7%) (Keller et al. 2013). Thus, despite multifaceted benefits for commercial purpose, their presence may cause hazardous biological effects in the
nature. The unique properties of these nanoparticles leading to detrimental effect in
environment mainly comprises of (i) high specific surface area, (ii) sufficient reactive sites on the surface, and (iii) their easy mobility (Wiesner et al. 2006). In this
direction, researchers have reported the interactions of nanoparticles with living
organisms and little, if any, information is available on the fate and behavior of these
nanoparticles within the environment and on human health (Handy et al. 2008).
Thus, to narrow the scope of this review, the present chapter aims to emphasize the
widespread contamination of the environment due to nanoparticles manufacturing
and waste disposal, and highlights the importance of econanotoxicity of engineered
nanomaterials to the waste management community.
11.2 Naturally Occurring and Engineered Nanoparticles
With increased anthropogenic activities along with the technological advancements,
nanoparticles generate enormous waste materials contaminating the biosphere and
pose serious ecological risks. However, nanoparticles still existed and leached into
the environment even before the formal emergence of the field of nanotechnology.
Naturally occurring nanoparticles are ubiquitous in nature. Several geological processes are known to produce natural nanoparticles such as in the form of combustion
by-product,
automobile
exhaust,
aerosols,
and
volcanoes
(Bystrzejewska-Piotrowska et al. 2009). Further, in biological processes, biomolecules like protein, nucleic acids, ATP, membranes, cells, organelles, etc. are directly
released into the environment from the organisms, leading to the formation of
nanoparticles as a result of degradation of biological matters (Bhatt and Tripathi
2011). However, many of these natural and incidental nanomaterials also have certain distinctive characteristics that cannot be denied from an environmental chemistry perspective (Bernhardt et al. 2010).
Unlike the naturally occurring nanoparticles that are formed heterogeneously
and disseminated in the environment, ENPs are mostly homogeneous in terms of
size, shape, and structure. The two approaches for the production of ENPs are topdown and bottom-up fabrication method (Bhatt and Tripathi 2011). In the first
method, lithographic techniques cut large materials into sizes less than 30 nm.
Alternatively, macromaterial are ground in a ball mill for producing NPs having size
less than 30 nm (Borm et al. 2006). In contrast, bottom-up synthesis process is a
more suitable method to convert extremely small molecules or atoms to nanometer
level (Christian et al. 2008). The diameter-tuning of nanoparticles is especially
imperative and is regulated with media in which they are synthesized. While temperature and reaction time are important within the realms of wet-phase synthesis
protocol, precursor concentration, as well as reaction temperature, controls the
diameter of ENPs in gas phase. Moreover, dispersing additives are used to stop
D. Kundu et al.