Is it possible to split water with sound wave?

kevin_tee

I have been researching about splitting water including electrolysis, but I came across about using ultrasonic sound wave to split water, I search around and it said that water will decompose at 42000 hertz, is this true, because I am going to do it for my project. May anyone please give me a link and theory behind it because I couldn't find it. Thank you.

Bobbywhy

Cavitation in physics is the formation of vapor bubbles of a liquid in a region where the pressure of the liquid falls below its vapor pressure. The extreme pressure reduction literally “rips” the water molecules apart and creates a bubble. This bubble contains gas that had been dissolved in the liquid. Cavitation bubbles can easily be seen near the tips of a rapidly spinning propeller under water. For a good description of hydrodynamic cavitation, see: http://en.wikipedia.org/wiki/Cavitation

Cavitation in liquids may also be caused when the low pressure portion of a powerful acoustic (sound) wave "rips" the water molecules apart and causes bubbles to form. There is no specific frequency that causes cavitation; a wide range from very low frequencies through ultrasonic frequencies all will cause cavitation in water. When a cavitation bubble collapses it compresses the gas and vapor inside it to an extremely high temperature. This can be used to cause chemical reactions not possible without acoustic cavitation. Under some specific conditions the process will emit visible light called “sonoluminescence”.

An excellent technical paper authored by some of the original pioneers in the field is this:
“Acoustic cavitation and its chemical consequences”
By Kenneth S. Suslick, et al.
http://www.scs.illinois.edu/suslick/...trans99335.pdf

See these images for acoustic cavitation:
http://www.google.com/search?q=acous...w=1333&bih=648

Suggested search terms you may use in Google searches to learn more:

hydrodynamic cavitation
physics of acoustic cavitation in liquids
acoustic cavitation ultrasound
sonochemistry
sonoluminescence

Just as a side note, in high power sonar systems there is always the possibility of trying to transmit so much acoustic power that cavitation occurs at the face of the output transmitter (projector). This bubble field will damage the projector quickly and must be avoided. Worse yet, the bubble field drastically changes the acoustic impedance of that water and so the output sound field is attenuated. This is highly undesirable as well. As a result, sonar engineers always avoid allowing cavitation to occur.

Cheers,
Bobbywhy

NascentOxygen

✈ https://www.google.com.au/search?q=split+water+using+ultrasound
✈ https://www.google.com.au/search?q=decompose+water+using+ultrasound

kevin_tee

thank you so much

Bobbywhy

Thank you, NascentOxygen, for addressing the kevin tee's question.

My lesson learned: pay closer attention to what the OP is asking.

Cheers,
Bobbywhy

kevin_tee

Can hydrogen and oxygen be harvest and used? I found out that that the temperature of cavitation is more than 5000 kelvin, so will hydrogen and oxygen be combust before it can be used?

Bobbywhy

kevin tee, OOPS! Excuse me, please. I mistakenly posted all that information about cavitation without understanding your question. While it is true that acoustic cavitation bubbles, when collapsing, can generate temperatures above 5,000 degrees Kelvin, this process alone does not “split” water into Hydrogen and Oxygen.

May I suggest you begin by reading and studying this Wikipedia article?
http://en.wikipedia.org/wiki/Water_splitting
Here you will discover many various ways to split water. Please use the references at the bottom.

Here find an article about using ultrasound to generate free radicals from sonolysis of water: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171683/

Here is an article called “Direct Water Splitting Through Vibrating Piezoelectric
Microfibers in Water”.
"ABSTRACT We propose a mechanism, a piezoelectrochemical effect for the
direct conversion of mechanical energy to chemical energy. This phenomenon is
further applied for generating hydrogen and oxygen via direct water decomposition
by means of as-synthesized piezoelectric ZnO microfibers and BaTiO3 microdendrites."
http://www.geology.wisc.edu/.../Hong..._Chem_Lett.pdf

Here is a paper called “Sonophotocatalytic decomposition of water using TiO2 photocatalyst”. “In the present work, simultaneous irradiation of ultrasound and light in order to decompose water to hydrogen and oxygen continuously has been attempted. This attempt, if proved successful, will be a typical example for a hybrid effect.”
http://www.ncbi.nlm.nih.gov/pubmed/11105323

kevin tee, I encourage you to continue searching for new, energy efficient, and innovative ways to decompose water. Your research, if successful, has the potential to revolutionize our entire production of energy.

Cheers and good luck,
Bobbywhy

CWatters

Either way you can't run a car on pure water :-)