Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater | Uchida et al. Nanoscale Research Letters 2011 6 295 http content 6 1 295 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access 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 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 Introduction Small bubbles such as microbubbles MBs usually range from 10-4 to 10-6 m in diameter and nanobubbles NBs less than 10-6 m in diameter have various properties that differ from macroscopic bubbles greater than 10-3 m in diameter . For example smaller bubbles have lower buoyancies so they take longer to reach the liquid surface and thus they have longer residence times. Also micro- and nanobubbles MNBs have either negative or positive zeta potentials 1 2 . This property inhibits the easy agglomeration or coalescence of bubbles and results in the relatively uniform size distribution of MNBs. Additionally the smaller the bubble the larger the specific interfacial area. Thus the efficient physical adsorption of impurities included in the solutions on the bubble surface is expected. MNBs have now
