A Study Aimed at Understanding the Use of Nanomaterial-Treated Filters …
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The functionalization of gold nanoparticles with citrate occurs during their synthesis,
as sodium citrate acts as the reducing agent in the reaction.
Heavy Metal Uptake of Gold Nanoparticles
The L-cysteine-functionalized gold nanoparticles and citrate-capped gold nanoparticles in solution (1 mL aliquots) were incubated while rotating at room temperature
in a zinc (II) (1 mM) solution at different concentrations (0.05, 0.1, and 0.12 mM).
The functionalized gold nanoparticles on stainless-steel wool filters were incubated
without stirring at room temperature in a zinc (II) solution (1 mL) and 10 mL of deionized water with a 10:1 solution to heavy metal ratio. For comparison and testing of
the selectivity of L-cysteine and citrate, the functionalized gold nanoparticles, in
solution and on stainless-steel wool filters, were also incubated in the same manner
with a copper (II) (1 mM) solution.
Results and Discussion
Synthesis and Characterization of Unbound Gold
Nanoparticles in Solution and Bound on Stainless-Steel Wool
Support
Gold nanospheres were prepared in solution through a wet chemical approach [4, 5].
In this approach, sodium citrate served as both a reducing and capping agent. The
solution turned a ruby red color, which is indicative of production of gold nanospheres
[4, 15]. The scanning electron microscopy was collected to elucidate nanoparticles
morphology, distribution and size. Scanning electron microscopy images depicted
in Fig. 1 confirmed the production of spherical shape of the gold nanoparticles of
approximately 21 ± 1 nm in diameter. The gold nanoparticles in solution were
highly monodisperse in size and shape. The hydrodynamic radius of the nanoparticles investigated by the dynamic light-scattering analysis, in their aqueous environment, was 24 ± 0.1 nm. These results are in agreement with the dimensions
collected from the scanning electron microscopy studies on dried gold nanoparticles. Ultraviolet–visible spectroscopy was employed to evaluate the optical properties of gold nanoparticles. The results show the presence of a sharp, single peak at
524 nm (Fig. 2), which is indicative of monodisperse and spherical gold nanoparticles. This peak at ≈524 nm corresponds to the plasmon band (collective oscillation of
electrons) for individual (i.e. not aggregated) spherical gold nanoparticles [16]. The
distinctive localized surface plasmon resonance can be used to probe environment
for colorimetric sensing applications.
97
The functionalization of gold nanoparticles with citrate occurs during their synthesis,
as sodium citrate acts as the reducing agent in the reaction.
Heavy Metal Uptake of Gold Nanoparticles
The L-cysteine-functionalized gold nanoparticles and citrate-capped gold nanoparticles in solution (1 mL aliquots) were incubated while rotating at room temperature
in a zinc (II) (1 mM) solution at different concentrations (0.05, 0.1, and 0.12 mM).
The functionalized gold nanoparticles on stainless-steel wool filters were incubated
without stirring at room temperature in a zinc (II) solution (1 mL) and 10 mL of deionized water with a 10:1 solution to heavy metal ratio. For comparison and testing of
the selectivity of L-cysteine and citrate, the functionalized gold nanoparticles, in
solution and on stainless-steel wool filters, were also incubated in the same manner
with a copper (II) (1 mM) solution.
Results and Discussion
Synthesis and Characterization of Unbound Gold
Nanoparticles in Solution and Bound on Stainless-Steel Wool
Support
Gold nanospheres were prepared in solution through a wet chemical approach [4, 5].
In this approach, sodium citrate served as both a reducing and capping agent. The
solution turned a ruby red color, which is indicative of production of gold nanospheres
[4, 15]. The scanning electron microscopy was collected to elucidate nanoparticles
morphology, distribution and size. Scanning electron microscopy images depicted
in Fig. 1 confirmed the production of spherical shape of the gold nanoparticles of
approximately 21 ± 1 nm in diameter. The gold nanoparticles in solution were
highly monodisperse in size and shape. The hydrodynamic radius of the nanoparticles investigated by the dynamic light-scattering analysis, in their aqueous environment, was 24 ± 0.1 nm. These results are in agreement with the dimensions
collected from the scanning electron microscopy studies on dried gold nanoparticles. Ultraviolet–visible spectroscopy was employed to evaluate the optical properties of gold nanoparticles. The results show the presence of a sharp, single peak at
524 nm (Fig. 2), which is indicative of monodisperse and spherical gold nanoparticles. This peak at ≈524 nm corresponds to the plasmon band (collective oscillation of
electrons) for individual (i.e. not aggregated) spherical gold nanoparticles [16]. The
distinctive localized surface plasmon resonance can be used to probe environment
for colorimetric sensing applications.