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S. E. H. Murph and A. Goriounova
by-products into the environment. The adverse effect of heavy metals and radionuclides on the environment has been recognized by the scientific community. While
numerous strategies have been developed for decades, [1, 2] new, cost-effective, and
efficient technologies are still being developed and implemented [3].
In recent years, there has been a growing interest in the fields of nanomaterials and
nanotechnology [1, 3–7]. Nanotechnology is the cutting-edge branch of technology
that deals with the manipulation of matter on the nanometer scale (1–100 nm). A
nanometer is one-billionth (10
–9 ) of a meter [4, 8]. Why are we captivated by nanomaterials? At the nanoscale, materials have unusual properties and behave differently
than both bulk matter and their constituent atoms or molecules [4, 8]. Furthermore,
their properties are tunable as a function of nanoparticle’s size, shape, aggregation
state, and local environment [8]. This makes them fascinating and highly valuable
for applications across many fields from engineering to medicine. Given the myriad
of emerging applications in the field, nanotechnology will likely revolutionize the
future and have a paramount impact on our society.
The first nanomaterial, buckminsterfullerene, was discovered in 1985 by Richard
Smalley and Bob Curl. This discovery influenced scientists to consider the world
at an atomic level [8]. Since then, a large variety of novel nanomaterials have been
produced and developed, including metallic, metallic oxide, polymers, quantum dots,
among many others [3–8]. In the last decades, these nanomaterials have been successfully applied to the medical field, computer engineering, enhancement of instrumental
analysis, material development, and environmental remediation [4, 5]. Due to the
unique properties of nanomaterials in terms of reactivity, size to surface area ratio,
and tunability, [1, 4, 8, 9] they are prime candidates for the uptake of heavy metals
from the environment.
There have been multiple studies that focus on the use of nanoparticles for
the uptake of heavy metals in the environment. For example, Dupont et al. [6]
demonstrated the ability of ethylenediaminetetraacetic acid (EDTA)-functionalized
magnetic, iron oxide (Fe 3 O 4 ), and nonmagnetic, silica (SiO 2 ) and titania (TiO 2 ),
nanoparticles to selectively uptake earth metals from aqueous solutions. Recently,
Warner et al. [7] showed the ability of nanoparticles functionalized with five different
ligands to serve as sorption agents for lead, mercury, copper, silver, cadmium, and
cobalt. It was reported by Ojemaye [10] that nanoparticles functionalized with thiols,
carboxylic acids, silanes, or nitrogen-containing ligands are most efficient in the
uptake of heavy metals due to the functional groups’ ability to bond with the heavy
metal ions. All these techniques are effective at adsorbing heavy metals present in
aqueous environments onto their surface. However, these strategies lack the capability of being practically implemented for widespread water remediation as the
fabrication of nanomaterials in large quantities is still limited. Moreover, nanomaterials’ impact on the environment is currently unknown. Recent studies show
that gold nanoparticles stabilized with labile ligands (e.g. citrate or cetyltrimethylammonium bromide) aggregate irreversibly in groundwater, potentially reducing
their environmental mobility. As a result, gold nanoparticles’ movement through
different ecosystem compartments might be better considered as the movement of
large heteroaggregate species, rather than as individual nanoparticles [11]. However,
S. E. H. Murph and A. Goriounova
by-products into the environment. The adverse effect of heavy metals and radionuclides on the environment has been recognized by the scientific community. While
numerous strategies have been developed for decades, [1, 2] new, cost-effective, and
efficient technologies are still being developed and implemented [3].
In recent years, there has been a growing interest in the fields of nanomaterials and
nanotechnology [1, 3–7]. Nanotechnology is the cutting-edge branch of technology
that deals with the manipulation of matter on the nanometer scale (1–100 nm). A
nanometer is one-billionth (10
–9 ) of a meter [4, 8]. Why are we captivated by nanomaterials? At the nanoscale, materials have unusual properties and behave differently
than both bulk matter and their constituent atoms or molecules [4, 8]. Furthermore,
their properties are tunable as a function of nanoparticle’s size, shape, aggregation
state, and local environment [8]. This makes them fascinating and highly valuable
for applications across many fields from engineering to medicine. Given the myriad
of emerging applications in the field, nanotechnology will likely revolutionize the
future and have a paramount impact on our society.
The first nanomaterial, buckminsterfullerene, was discovered in 1985 by Richard
Smalley and Bob Curl. This discovery influenced scientists to consider the world
at an atomic level [8]. Since then, a large variety of novel nanomaterials have been
produced and developed, including metallic, metallic oxide, polymers, quantum dots,
among many others [3–8]. In the last decades, these nanomaterials have been successfully applied to the medical field, computer engineering, enhancement of instrumental
analysis, material development, and environmental remediation [4, 5]. Due to the
unique properties of nanomaterials in terms of reactivity, size to surface area ratio,
and tunability, [1, 4, 8, 9] they are prime candidates for the uptake of heavy metals
from the environment.
There have been multiple studies that focus on the use of nanoparticles for
the uptake of heavy metals in the environment. For example, Dupont et al. [6]
demonstrated the ability of ethylenediaminetetraacetic acid (EDTA)-functionalized
magnetic, iron oxide (Fe 3 O 4 ), and nonmagnetic, silica (SiO 2 ) and titania (TiO 2 ),
nanoparticles to selectively uptake earth metals from aqueous solutions. Recently,
Warner et al. [7] showed the ability of nanoparticles functionalized with five different
ligands to serve as sorption agents for lead, mercury, copper, silver, cadmium, and
cobalt. It was reported by Ojemaye [10] that nanoparticles functionalized with thiols,
carboxylic acids, silanes, or nitrogen-containing ligands are most efficient in the
uptake of heavy metals due to the functional groups’ ability to bond with the heavy
metal ions. All these techniques are effective at adsorbing heavy metals present in
aqueous environments onto their surface. However, these strategies lack the capability of being practically implemented for widespread water remediation as the
fabrication of nanomaterials in large quantities is still limited. Moreover, nanomaterials’ impact on the environment is currently unknown. Recent studies show
that gold nanoparticles stabilized with labile ligands (e.g. citrate or cetyltrimethylammonium bromide) aggregate irreversibly in groundwater, potentially reducing
their environmental mobility. As a result, gold nanoparticles’ movement through
different ecosystem compartments might be better considered as the movement of
large heteroaggregate species, rather than as individual nanoparticles [11]. However,