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Bubbles Experiment

  1. Aug 20, 2014 #1
    I am doing an experiment in which I have to remove gas bubbles within a liquid medium. The liquid is contained within a small plastic mould of about 2cm diameter. The conditions of the experiment cannot be changed. My question is, can I practically remove the bubbles.

    I cannot stir the liquid or make contact. My main thought was trying to use ultrasound in the hope of collapsing the bubbles. I made a quick ultrasound transmitter with an arduino module. The frequency was 40kHz but failed to cause any bubble formation or collapse. Does anyone know if a higher frequency would result in bubbles forming or collapsing or any practical ways that I can use.

    Thanks in advance
  2. jcsd
  3. Aug 20, 2014 #2


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    Hello and welcome to PF.
    It's a common technique to use a partial vacuum. If you get the bubbles to increase in size under reduced pressure, they are more likely to rise to the top and burst. The Vacu-vin is a device that works well on wine bottles. It takes most of the air out of a bottle and will dispel the small bubbles, formed by secondary fermentation much quicker than decanting or leaving the wine to stand (breathe).
    The reduced pressure technique is also, commonly used to get rid of the bubbles in plaster of Paris used in fine metal casting (jewellery).
    If you have access to a vacuum pump and a bell jar, it would be easy to try.
  4. Aug 22, 2014 #3

    Simon Bridge

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    Collapsing the bubbles by ultrasound would be much the same as stirring the liquid - actually much more violent if you are relying on ultrasonic cavitation - and you said you could not do that. Is it just the physical contact you cannot have - say: the walls get in the way? Then, if stirring would otherwise be an option, how about electromagnetic stirring?

    Possibly you just need to remove the bubbles before carefully putting the liquid into the mould.
    Whatever you choose, you'll need to do some experimentation to sort out a good solution.
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