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Nano sand filter with functionalized nanoparticles embedded in anodic aluminum oxide templates

View Article: PubMed Central - PubMed

ABSTRACT

Since the ancient Egyptians had used sand as filter media for water purification, its principle has been inherited through generations and it is still being used now in industries. The sand filter consists of sand literally, and the voids within the sand bed are the pores for filtration. Here we present a filtration principle using nanoparticles, so that the voids between the nanoparticles can be considered as effective pores in nanoscale dimension. Anodic aluminum oxide (AAO) membrane has been used as the working template, and the nanoparticles have been injected and embedded within the pores of the AAO template. Nanoparticles with multiple sizes have been used in order to obtain smaller voids. Moreover, the nanoparticles have been functionalized, or electrically charged, with arginine/phenylalanine (RF) peptide group. In this way, filtration performance for charged particles or molecules, such as methylene blue, has been enhanced. Consequently, this study is expected to provide a new principle for fabrication of nano voids, or nano pores, and for filtration in nanoscale dimension.

No MeSH data available.


Hydraulic pressure drops across the working templates for various flow fluxes.Differential pressure of water flow was measured to obtain the pressure drop across the AAO template embedded with nanoparticles (Supplementary Fig. 2).
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f6: Hydraulic pressure drops across the working templates for various flow fluxes.Differential pressure of water flow was measured to obtain the pressure drop across the AAO template embedded with nanoparticles (Supplementary Fig. 2).

Mentions: One of the major purposes of this study is to fabricate voids in nanoscale dimension. However, geometry of the voids between the nanoparticles is complicated and they cannot be evaluated on the cross sections. Therefore, we measured hydraulic pressure drop across the nanoparticle-embedded AAO templates so that we could compare the voids relatively for various combinations of the nanoparticles (Supplementary Fig. 2). Deionized (DI) water was pumped with a syringe pump and differential pressure across the AAO template was measured (Romemount 3051TG Transmitter, Jackwell Inc.). Figure 6 shows the hydraulic pressure drop for various fluxes and various combinations of nanoparticles in the AAO templates. As smaller nanoparticles are embedded, the voids between the nanoparticles are expected to be narrower, which means that hydraulic passages become narrower. Accordingly, the results are showing that the AAO templates with smaller nanoparticles have produced higher pressure drop for the same flux than those with larger particles. Therefore, this hydraulic measurement suggests that the voids between the nanoparticles, which are the hydraulic passages, could be modulated by embedding nanoparticles with different sizes. And this result also shows that the nanoparticles are trapped, or confined, stably inside the pores. The hydraulic characteristics vary consistently with the flow flux, so it can be inferred that there was no serious loss of the particles during the tests. For this reason, further treatment for stabilization of the particles was not necessary as long as the flow is applied from the top side of the AAO. And it is also remarkable that the particles with (RF)4 produced higher pressure drops than those without it for the same size of the nanoparticles. As discussed in the above paragraph, denser embedment is expected when the particles have the same charge with inner wall of the template. Accordingly, this result is showing that the particles with (RF)4 are embedded more densely, making smaller voids than those without it.


Nano sand filter with functionalized nanoparticles embedded in anodic aluminum oxide templates
Hydraulic pressure drops across the working templates for various flow fluxes.Differential pressure of water flow was measured to obtain the pressure drop across the AAO template embedded with nanoparticles (Supplementary Fig. 2).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120303&req=5

f6: Hydraulic pressure drops across the working templates for various flow fluxes.Differential pressure of water flow was measured to obtain the pressure drop across the AAO template embedded with nanoparticles (Supplementary Fig. 2).
Mentions: One of the major purposes of this study is to fabricate voids in nanoscale dimension. However, geometry of the voids between the nanoparticles is complicated and they cannot be evaluated on the cross sections. Therefore, we measured hydraulic pressure drop across the nanoparticle-embedded AAO templates so that we could compare the voids relatively for various combinations of the nanoparticles (Supplementary Fig. 2). Deionized (DI) water was pumped with a syringe pump and differential pressure across the AAO template was measured (Romemount 3051TG Transmitter, Jackwell Inc.). Figure 6 shows the hydraulic pressure drop for various fluxes and various combinations of nanoparticles in the AAO templates. As smaller nanoparticles are embedded, the voids between the nanoparticles are expected to be narrower, which means that hydraulic passages become narrower. Accordingly, the results are showing that the AAO templates with smaller nanoparticles have produced higher pressure drop for the same flux than those with larger particles. Therefore, this hydraulic measurement suggests that the voids between the nanoparticles, which are the hydraulic passages, could be modulated by embedding nanoparticles with different sizes. And this result also shows that the nanoparticles are trapped, or confined, stably inside the pores. The hydraulic characteristics vary consistently with the flow flux, so it can be inferred that there was no serious loss of the particles during the tests. For this reason, further treatment for stabilization of the particles was not necessary as long as the flow is applied from the top side of the AAO. And it is also remarkable that the particles with (RF)4 produced higher pressure drops than those without it for the same size of the nanoparticles. As discussed in the above paragraph, denser embedment is expected when the particles have the same charge with inner wall of the template. Accordingly, this result is showing that the particles with (RF)4 are embedded more densely, making smaller voids than those without it.

View Article: PubMed Central - PubMed

ABSTRACT

Since the ancient Egyptians had used sand as filter media for water purification, its principle has been inherited through generations and it is still being used now in industries. The sand filter consists of sand literally, and the voids within the sand bed are the pores for filtration. Here we present a filtration principle using nanoparticles, so that the voids between the nanoparticles can be considered as effective pores in nanoscale dimension. Anodic aluminum oxide (AAO) membrane has been used as the working template, and the nanoparticles have been injected and embedded within the pores of the AAO template. Nanoparticles with multiple sizes have been used in order to obtain smaller voids. Moreover, the nanoparticles have been functionalized, or electrically charged, with arginine/phenylalanine (RF) peptide group. In this way, filtration performance for charged particles or molecules, such as methylene blue, has been enhanced. Consequently, this study is expected to provide a new principle for fabrication of nano voids, or nano pores, and for filtration in nanoscale dimension.

No MeSH data available.