18.4 Destiny of Used Nanoparticles
Fabricated nanoparticles employed in wastewater treatment are generally regarded
as consumables despite of their use in large amounts. Their fruitful lifecycle must be
measured via the working time span through which a reasonable efficiency with
regard to contaminant elimination and methodology price is assured. Because of
their nanoscale dimensions, reactivity, stability, and mobility in the water system
entail the chance of adverse effects to the living organisms; therefore used
nanoparticles must be handled appropriately. Therefore, it is vital to investigate
whether their revival, recovery, and safe discarding could be attained. Moreover,
considering their loading with lethal contaminants, any degradation, leaching, or
their conversion via chemical reactions in the ecosystem must additionally be
checked while scheming a route to treat wastewater.
Over the last few years, several theoretical and experimental researchers have
devoted their efforts to investigate the activities of inorganic nanoparticles in water
or soil and the interaction of engineered nanoparticles with living beings as a cause
of ecotoxicity (Moore 2006; Navarro et al. 2008). Likewise, an incessant attempt to
build reproducible and consistent risk testing approaches and evaluation of living
being exposure to engineered nanoparticles is still in progress. A collection of
analytical tools has been introduced to examine the effect of nanoparticle size,
shape, aggregation, and dissolution. A large number of reports demonstrate the
nanoparticle cytotoxicity corresponding to human disclosure progressing the knowledge about their performance in living systems (Lewinski et al. 2008). However, the
findings are contentious, and in majority of the reports, it is not clear which features
are responsible for the uptake of cell and toxicity. Generally, Au nanoparticles seem
to be the most stable and non-toxic when assessed with cells of freshwater algae and
fish. Based on their surface, these nanoparticles might be easily absorbed in the cells
of fish. The different adverse effects of titania nanoparticles on the mice have been
investigated via in vivo studies. It has been found that these nanoparticles aggravate
oxidative deoxyribose nucleic acid damage, inflammation, clastogenicity, and
genotoxicity in mice (Trouiller et al. 2009). Another report demonstrated that the
metabolism of pentachlorophenol in zebrafish larvae has been increased significantly
in the presence of titania nanoparticles, so it can be concluded that these
nanoparticles induce oxidative damage during the early stages of its development.
Taking the above contents into account, several researchers have devoted their
efforts to identifying the fate of nanoparticles used for the purification of wastewater.
Schwab et al. have spiked titania, silver, and zinc oxide nanoparticles in five
different samples of water, and they observed that although nanoparticles can be
removed to high extent by using techniques, such as membrane filtration, the treated
water was still found to possess noticeable metallic contents, which may present
threats to the health of human being (Chalew Talia et al. 2013). The as-Synthesized
ZnO nanoparticles may become toxic upon their dissolution and dissociation to Zn
ions and active oxygen, whereas light-induced reactions may also take part in this
course. The phytotoxicity and nanoparticle interactions with plants at seedling stage
678
B. Akram et al.
Fabricated nanoparticles employed in wastewater treatment are generally regarded
as consumables despite of their use in large amounts. Their fruitful lifecycle must be
measured via the working time span through which a reasonable efficiency with
regard to contaminant elimination and methodology price is assured. Because of
their nanoscale dimensions, reactivity, stability, and mobility in the water system
entail the chance of adverse effects to the living organisms; therefore used
nanoparticles must be handled appropriately. Therefore, it is vital to investigate
whether their revival, recovery, and safe discarding could be attained. Moreover,
considering their loading with lethal contaminants, any degradation, leaching, or
their conversion via chemical reactions in the ecosystem must additionally be
checked while scheming a route to treat wastewater.
Over the last few years, several theoretical and experimental researchers have
devoted their efforts to investigate the activities of inorganic nanoparticles in water
or soil and the interaction of engineered nanoparticles with living beings as a cause
of ecotoxicity (Moore 2006; Navarro et al. 2008). Likewise, an incessant attempt to
build reproducible and consistent risk testing approaches and evaluation of living
being exposure to engineered nanoparticles is still in progress. A collection of
analytical tools has been introduced to examine the effect of nanoparticle size,
shape, aggregation, and dissolution. A large number of reports demonstrate the
nanoparticle cytotoxicity corresponding to human disclosure progressing the knowledge about their performance in living systems (Lewinski et al. 2008). However, the
findings are contentious, and in majority of the reports, it is not clear which features
are responsible for the uptake of cell and toxicity. Generally, Au nanoparticles seem
to be the most stable and non-toxic when assessed with cells of freshwater algae and
fish. Based on their surface, these nanoparticles might be easily absorbed in the cells
of fish. The different adverse effects of titania nanoparticles on the mice have been
investigated via in vivo studies. It has been found that these nanoparticles aggravate
oxidative deoxyribose nucleic acid damage, inflammation, clastogenicity, and
genotoxicity in mice (Trouiller et al. 2009). Another report demonstrated that the
metabolism of pentachlorophenol in zebrafish larvae has been increased significantly
in the presence of titania nanoparticles, so it can be concluded that these
nanoparticles induce oxidative damage during the early stages of its development.
Taking the above contents into account, several researchers have devoted their
efforts to identifying the fate of nanoparticles used for the purification of wastewater.
Schwab et al. have spiked titania, silver, and zinc oxide nanoparticles in five
different samples of water, and they observed that although nanoparticles can be
removed to high extent by using techniques, such as membrane filtration, the treated
water was still found to possess noticeable metallic contents, which may present
threats to the health of human being (Chalew Talia et al. 2013). The as-Synthesized
ZnO nanoparticles may become toxic upon their dissolution and dissociation to Zn
ions and active oxygen, whereas light-induced reactions may also take part in this
course. The phytotoxicity and nanoparticle interactions with plants at seedling stage
678
B. Akram et al.