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Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater.

Uchida T, Oshita S, Ohmori M, Tsuno T, Soejima K, Shinozaki S, Take Y, Mitsuda K - Nanoscale Res Lett (2011)

Bottom Line: Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly.MNBs in pure water and in 1% NaCl solutions were spherical or oval.When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.PACS: 68.03.-g, 81.07.-b, 92.40.qc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan. t-uchida@eng.hokudai.ac.jp.

ABSTRACT
Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.PACS: 68.03.-g, 81.07.-b, 92.40.qc.

No MeSH data available.


Related in: MedlinePlus

Various TEM images of freeze-fractured replica of the wastewater containing MNBs. Each scale bar indicates 500 nm. An ice crystallite with a faceted smooth surface was located in the center of each picture (a, b), and surrounded by a rough surface composed of fine particles (impurities). The remaining area around the particles is the glass state of the solution.
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Figure 4: Various TEM images of freeze-fractured replica of the wastewater containing MNBs. Each scale bar indicates 500 nm. An ice crystallite with a faceted smooth surface was located in the center of each picture (a, b), and surrounded by a rough surface composed of fine particles (impurities). The remaining area around the particles is the glass state of the solution.

Mentions: The replica observations for the wastewater with MNBs exhibited obviously different images from those mentioned above. Several parts of the replica samples prepared from the wastewater had a rough surface including many fine particles (less than 10-7 m in diameter) as depicted in Figure 4a, b. These fine particles resulted from either invisible small particles or from the agglomeration of the condensed soluble impurities such as glucide or calcium sulfate, both of which are considered to be included in the original wastewater. In addition, we sometimes found micron-sized ice crystallites among the fine particles, and found that they had crystalline facets with a smooth surface (center of Figures 4a, b). These ice crystallites are considered to be formed in the polluted solution during the sample quenching. The remaining area around the fine particles is the glassy body. The smooth surface of ice crystallite suggested that the observed rough surface surrounding the ice did not come from any artifacts on the replica during the sample preparation, such as frost deposit. The analogous features for disaccharide solutions [20] suggested that the original solution included a relatively high concentration of impurities because the crystallites were small and faceted, which indicated they grew slowly due to the impurities.


Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater.

Uchida T, Oshita S, Ohmori M, Tsuno T, Soejima K, Shinozaki S, Take Y, Mitsuda K - Nanoscale Res Lett (2011)

Various TEM images of freeze-fractured replica of the wastewater containing MNBs. Each scale bar indicates 500 nm. An ice crystallite with a faceted smooth surface was located in the center of each picture (a, b), and surrounded by a rough surface composed of fine particles (impurities). The remaining area around the particles is the glass state of the solution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211361&req=5

Figure 4: Various TEM images of freeze-fractured replica of the wastewater containing MNBs. Each scale bar indicates 500 nm. An ice crystallite with a faceted smooth surface was located in the center of each picture (a, b), and surrounded by a rough surface composed of fine particles (impurities). The remaining area around the particles is the glass state of the solution.
Mentions: The replica observations for the wastewater with MNBs exhibited obviously different images from those mentioned above. Several parts of the replica samples prepared from the wastewater had a rough surface including many fine particles (less than 10-7 m in diameter) as depicted in Figure 4a, b. These fine particles resulted from either invisible small particles or from the agglomeration of the condensed soluble impurities such as glucide or calcium sulfate, both of which are considered to be included in the original wastewater. In addition, we sometimes found micron-sized ice crystallites among the fine particles, and found that they had crystalline facets with a smooth surface (center of Figures 4a, b). These ice crystallites are considered to be formed in the polluted solution during the sample quenching. The remaining area around the fine particles is the glassy body. The smooth surface of ice crystallite suggested that the observed rough surface surrounding the ice did not come from any artifacts on the replica during the sample preparation, such as frost deposit. The analogous features for disaccharide solutions [20] suggested that the original solution included a relatively high concentration of impurities because the crystallites were small and faceted, which indicated they grew slowly due to the impurities.

Bottom Line: Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly.MNBs in pure water and in 1% NaCl solutions were spherical or oval.When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.PACS: 68.03.-g, 81.07.-b, 92.40.qc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan. t-uchida@eng.hokudai.ac.jp.

ABSTRACT
Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.PACS: 68.03.-g, 81.07.-b, 92.40.qc.

No MeSH data available.


Related in: MedlinePlus