Bubbles contained in a liquid are visible to the eyes when the bubble sizes are large enough to see, as we can see bubbles in carbonated drinks or those coming from the air diffuser in a water tank.
Bubbles with the size of a few millimeters in diameter show visible surfacing action in a liquid, and the presence of fine bubbles of dozens of microns in diameter can be confirmed with white turbidity in a liquid, because these bubbles are scattering substances.
Bubbles in diameter smaller than the wavelength of light are called ultrafine bubbles, and they are too small to see.
Ultrafine bubbles have many other remarkable features that ordinary bubbles do not possess.
For example, these bubbles can stay in a liquid for a long time, and are electrically charged, and are extra highly pressured as well.
These special features of ultrafine bubbles have attracted attention from many industries such as food, cosmetics, chemical, medical, semi-conductor, and agriculture.
Fine bubble (micro, nano-size)
||Ordinary bubbles rise in the water rapidly and burst on the water surface. Fine bubbles, on the other hand, stay in water because they are so small in size and extremely slow to rise. Bubbles in diameter of 10µm rise only 3mm per minute.
||An interface is a surface forming a common boundary among two different phases of matter; gas and liquid, liquid and liquid, liquid and solid, and solid and solid.
Pressure is generated between the surfaces with surface tension. As the bubble size becomes smaller, the higher the inner pressure becomes due to surface tension.
The bubbles are further compressed, which makes the inner pressure even higher. Logically, the pressurization process is infinite. Pressurization also promotes dissolution of gas into the water (Henry's Law).
|Surface Potential Characteristics
||Because fine bubbles have a colloidal characteristic and are negatively charged, they repel each other. For this characteristic, fine bubbles are not bonded to each other, and bubble density is not reduced.
||Fine bubbles are self-pressurized to burst, dissolving water and nitrogen, and radicals are generated. There are several theories for the formulation mechanism, and no consensus has been made yet.
Ultrafine Bubbles (nano-size)
||Ultrafine bubbles have been confirmed to stay in a liquid for over six months.
||Nano-size bubbles do not scatter visible light, making the water solution look transparent.
Participation in international symposiums and tradeshows
International Symposium of Fine Bubbles
POWTECH 2013 (international trade show for powder, granule, and bulk solids technologies), April 23-25, 2013, Nuremberg, Germany
Presented FBI international standardization activity at POWTECH 2013, April 23-25, 2013, Nuremberg, Germany
Fine bubble and ultrafine bubble technologies video by FBIA (16 min.)