Is there a "Microbubble Self-Collapsing Phenomenon” ?
When microbubbles are made, does the Self-Collapsing Phenomenon occur ?
We receive many inquiries about the “Microbubbles self-collapsing phenomenon due to self-shrinking" because of one incorrect
assertion by one researcher that “microbubbles self-shrink then self-collapse”. Unfortunately many microbubble generator
manufacturers use this incorrect assertion in their advertising.
The researcher's claim that when microbubbles are made in water, microbubbles shrink automatically due to the "surface
tension of the bubble" so the pressure inside the bubble becomes infinite and then the bubbles are crushed by water pressure
creating very high temperatures and very strong energy.
Based on this claim, many manufacturers of microbubble generators advertise "microbubbles can make free radicals that kill
viruses" or "wastewater can be treated with only microbubbles because organic matter is decomposed by microbubbles".
This researcher from an authoritative national research institution in Japan made this claim so many people who hear this claim
think "they can solve their technical problems with microbubbles only" or "microbubbles have unlimited possibilities ".
"Microbubble Self-Collapsing Phenomenon due to self-shrinking" has not been replicated elsewhere.
It is a phenomenon that only a very few people insist on.
“Microbubble Self-Collapsing Phenomenon due to self-shrinking” is a phenomenon that only a very few people claim
to be true as far as we know.
If it is true that microbubbles self-shrink automatically and emit high energy from microbubbles only there would be many papers
written about this unprecedented chemical reaction method using this energy and published worldwide.
But there is no such thing.
Talking about this phenomenon, Mr. Akira Serizawa who is professor emeritus at Kyoto University in Japan says the following.
- This phenomenon is not consistent with the laws of physics.
- Microbubbles do not automatically shrink and collapse.
- If it’s true that many microbubbles in water automatically self-shrink and self-collapse the shock waves produced would
synergistically influence each other creating very high energy that would increase the water temperature. However, in reality
the temperatures don’t rise.
The "Collapsing phenomenon" of the bubble is an accepted phenomenon in ultrasonic chemistry.
However, without an external force such as "ultrasonic power", the bubbles will not collapse.
"Microbubble collapsing phenomenon" is an accepted confirmed phenomenon in the field of "ultrasonic chemistry".
However, this is completely different from the story of "microbubbles self-shrinking automatically ...".
When ultrasonic waves are irradiated into the liquid, dissolved gasses are pulled
in by the negative pressure and a bubble is created.
Continuing to apply ultrasonic waves to this bubble, the bubble gradually
grows because of the ultrasonic wave energy.
However, when the bubble grows up to a certain stage, it becomes unstable
and can not maintain its shape, so liquid enters into the bubble crashing and
At this moment, the inside temperature of the bubble reaches 5,500 °C, which is
comparable to the surface temperature of the sun, and a high-speed jet stream
of 400km/h will come out.
The right photo shows the moment the bubble is crushed.
(*The above content is an excerpt of Professor K. S. Suslick's report published in
Nikkei Science magazine of April 1989 issue. It is hard to obtain now, so if you
can contact us, we will give you a copy of the report.
In other words, "Microbubble collapsing phenomenon" is caused by a super elite bubble that has been continuously receiving
ultrasonic energy. Various reports have been issued around the world about this phenomenon in the field of ultrasonic chemistry,
and they are being replicated. This phenomenon is definitely accepted as true.
Erosion/corrosion of the ship propeller is a commonly well-known “bubble collapsing phenomenon”. It is also called cavitation
phenomenon. When the propeller rotates at high speed in water, local negative pressure is created and dissolved gas changes
to bubbles. When the bubble crashes due to water pressure, a large shock wave appears and the metal propeller will be damaged
or vibration will occur.
In order to apply this shock wave energy to chemical reaction, ultrasonic wave energy is used as a method to artificially induce
bubble collapsing phenomenon.
Large size bubble causes collapsing phenomenon.
It is wrong to think the smaller the bubble the better.
The size of bubble that caused the collapsing phenomenon by the irradiation of ultrasonic waves that appears in the above
report is about 150microns to 170microns.
The size of microbubble is generally defined as 10microns to several tens of microns, so you can see that the size of the bubble
that causes collapsing phenomenon is very large. Large size bubbles that can keep the maximum energy such as ultrasound will
crash, generating enormous energy.
In the microbubble / nanobubble industry, there is a trend that the smaller bubble is better. For example, we frequently see
advertisements that "xx thousands of nanobubbles are contained in 1mL of water". However, as you can see from the above
example that the large bubble causes collapsing phenomenon. The assumption that “a smaller bubble is superior” is wrong
because it limits the potential of the bubble.
We are warning against the current microbubble industry competing to create small bubbles. We should explore the technology
from the stance that the optimal bubble size is different depending on the use.
If the microbubble self-shrinks, it can not be used for flotation separation (DAF).
We think that it is clearly incorrect that just producing microbubbles only automatically means the collapsing phenomenon will
happen. Microbubbles have been generated in wastewater from a long time ago as a part of “flotation separation” (DAF). If the
microbubble self-collapsing phenomenon is true, the BOD/COD values in wastewater inexplicably reduce. But it is not confirmed
because it is impossible to decompose BOD/COD values by simply generating microbubbles. In addition, if microbubbles really
self-shrink, microbubbles would not rise and would not be usable for DAF.