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

Tsutomu Uchida1*, Seiichi Oshita2, Masayuki Ohmori3, Takuo Tsuno4, Koichi Soejima5, Satoshi Shinozaki5, Yasuhisa Take6 and Koichi Mitsuda6

Author Affiliations

1 Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan

2 Department of Biological and Environmental Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan

3 Department of Biological Science, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan

4 Tsuno Rice Fine Chemicals Co., Ltd., Wakayama 649-7194, Japan

5 R&D Center, Mayekawa MFG. Co., Ltd., Ibaraki 302-0118, Japan

6 Mixing Project, Nikuni Co., Ltd., Kanagawa 213-0032, Japan

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Nanoscale Research Letters 2011, 6:295  doi:10.1186/1556-276X-6-295

Published: 5 April 2011


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