A Study Aimed at Understanding the Use of Nanomaterial-Treated Filters …
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this limits the gold nanoparticles’ surface area available for contaminant uptake and
potentially affects their unique properties.
Although nanoparticles are viable options for environmental remediation, it is
important to develop simple, yet controllable, methods for water cleanup that can
be easily retrieved upon the capture of contaminants. Therefore, it is not practical to
simply release free nanoparticles into water streams because it would be difficult to
monitor individual particles and evaluate the remediation processes’ efficiency [3].
Magnetic nanoparticles that can be retrieved using magnets represent one possible
solution to this problem [12]. However, the magnetic properties of magnetic nanoparticles have been found to decrease in potency in wastewater, especially those that
have been modified with ligands [5, 7, 13]. Another viable alternative is the development of supported nanoparticles that can be used as efficient filters for contaminated water resources [1, 3, 4]. This has the dual benefit of preventing nanoparticles
from contaminating the environment and facilitating easier tracking and control of
both nanoparticles and the heavy metal uptake on nanoparticles. Murph et al. [1]
described recently a technique for the uptake of zinc vapors using nanoparticles
attached to stainless-steel filters. This technology is an environmentally safe and
effective method for the remediation of heavy metals and radionuclides that is easily
deployable and could be implemented in the field on contaminated waters. The photocatalytic activity of titania-gold (TiO 2 –Au) and silica-titania-gold (SiO 2 –TiO 2 –Au)
nano-composite mesoscale materials produced by a combination of both bottom-up
[14] and top-down approaches was demonstrated for the photodegradation of a model
contaminant, methyl orange, under ultraviolet and visible illumination [3].
This study describes the synthesis of nanoparticles on stainless-steel wool filters
that have been functionalized with an active ligand specifically designed to uptake
heavy metals. Stainless steel is nonreactive and resistant to rusting, which makes it
especially attractive for heavy metal uptake in an aqueous environment. The use of
sequestered nanomaterials instead of unbounded nanomaterials is beneficial as this
strategy eliminates any potential concerns regarding the unforeseen consequences of
environmental release of nanomaterials in the environment. Unbound nanoparticles
that are “free-flowing” in solution were also synthesized and used in this study for a
comparison of uptake efficiency.
Materials and Instrumentation
Chloroauric acid (HAuCl 4 ), sodium citrate (>99%), and L-cysteine (97%)
were purchased from Sigma-Aldrich. Zinc acetate and copper (II) nitrate
hemi(pentahydrate) were purchased from Sigma-Aldrich and used as sources for
zinc (II) and copper (II) ions, respectively. All aqueous solutions were prepared in
deionized water. Stainless-steel wool (Type 316L SSF) was used for the filters. All
mass measurements were made with a Mettler Toledo XPE105 balance. A Fischer
Scientific accuSpin Micro17R was used for centrifuging the gold nanoparticles. A
TECS USA MCS PDA with LS ultraviolet–visible was used to evaluate nanoparticle’s
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this limits the gold nanoparticles’ surface area available for contaminant uptake and
potentially affects their unique properties.
Although nanoparticles are viable options for environmental remediation, it is
important to develop simple, yet controllable, methods for water cleanup that can
be easily retrieved upon the capture of contaminants. Therefore, it is not practical to
simply release free nanoparticles into water streams because it would be difficult to
monitor individual particles and evaluate the remediation processes’ efficiency [3].
Magnetic nanoparticles that can be retrieved using magnets represent one possible
solution to this problem [12]. However, the magnetic properties of magnetic nanoparticles have been found to decrease in potency in wastewater, especially those that
have been modified with ligands [5, 7, 13]. Another viable alternative is the development of supported nanoparticles that can be used as efficient filters for contaminated water resources [1, 3, 4]. This has the dual benefit of preventing nanoparticles
from contaminating the environment and facilitating easier tracking and control of
both nanoparticles and the heavy metal uptake on nanoparticles. Murph et al. [1]
described recently a technique for the uptake of zinc vapors using nanoparticles
attached to stainless-steel filters. This technology is an environmentally safe and
effective method for the remediation of heavy metals and radionuclides that is easily
deployable and could be implemented in the field on contaminated waters. The photocatalytic activity of titania-gold (TiO 2 –Au) and silica-titania-gold (SiO 2 –TiO 2 –Au)
nano-composite mesoscale materials produced by a combination of both bottom-up
[14] and top-down approaches was demonstrated for the photodegradation of a model
contaminant, methyl orange, under ultraviolet and visible illumination [3].
This study describes the synthesis of nanoparticles on stainless-steel wool filters
that have been functionalized with an active ligand specifically designed to uptake
heavy metals. Stainless steel is nonreactive and resistant to rusting, which makes it
especially attractive for heavy metal uptake in an aqueous environment. The use of
sequestered nanomaterials instead of unbounded nanomaterials is beneficial as this
strategy eliminates any potential concerns regarding the unforeseen consequences of
environmental release of nanomaterials in the environment. Unbound nanoparticles
that are “free-flowing” in solution were also synthesized and used in this study for a
comparison of uptake efficiency.
Materials and Instrumentation
Chloroauric acid (HAuCl 4 ), sodium citrate (>99%), and L-cysteine (97%)
were purchased from Sigma-Aldrich. Zinc acetate and copper (II) nitrate
hemi(pentahydrate) were purchased from Sigma-Aldrich and used as sources for
zinc (II) and copper (II) ions, respectively. All aqueous solutions were prepared in
deionized water. Stainless-steel wool (Type 316L SSF) was used for the filters. All
mass measurements were made with a Mettler Toledo XPE105 balance. A Fischer
Scientific accuSpin Micro17R was used for centrifuging the gold nanoparticles. A
TECS USA MCS PDA with LS ultraviolet–visible was used to evaluate nanoparticle’s