I'm working on a project and I need to reduce the surface tension of water. I want you to tell me a way in order to reduce surface tension of water except changing the temperature.
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2$\begingroup$ The first idea that comes to mind is putting some drops of soap or detergent in the water. $\endgroup$– Shivam SarodiaCommented Nov 27, 2015 at 7:26
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$\begingroup$ yes find something that is able to interfere with the intermolecular attraction of the water molecules. Detergent works well for this. Introducing another pollutant like salt may work as well. $\endgroup$– JaywalkerCommented Nov 27, 2015 at 7:42
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$\begingroup$ Any soap, detergent, surfactant or emulsifier will achieve this. $\endgroup$– Arif BurhanCommented May 15, 2016 at 16:47
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3 Answers
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Reduction of surface tension of water can be done in several ways. A few of them are as follows:
Surfactants are compounds that lower the surface tension of a liquid like water, the interfacial tension between two liquids, or that between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
- Surface tension can change with the change with medium that is just above the liquid. For instance, If the medium is air the surface tension of water is $72 \times 10^{-3}\,\mathrm{N/m}$, but if the medium is vapour that will be $70 \times 10^{-3}\,\mathrm{N/m}$
- If there is any oil or oily compounds on the free surface of the water, then surface tension will be reduced.
- If you mix something to the water, then the surface tension will be changed.
- If you electrify the water then surface tension will be reduced.
Quoting from this link,
Existing surfactants can lower it either as a monomolecular layer on water surface (Langmuir monolayers) or by forming microemulsions. In the former, the bulk water composition is unchanged but the surface tension can be reduced from $72\,\mathrm{mN/m}$ to only about $20\,\mathrm{mN/m}$. The microemulsion can make the interfacial tension go to $1\,\mathrm{\mu N/m}$ but changes the water composition. We have shown, through measurement of capillary wave amplitudes using diffuse scattering of X-rays, that a bi-molecular layer of a three-tailed amphiphile, preformed ferric stearate (FeSt), on water surface , lowers the surface tension to about $1\,\mathrm{mN/m}$.
answered Nov 27, 2015 at 7:48
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A simple method is to lead the water with a another fluid with very low IFT ie. wets the material readily such as IPA. This is a standard method used where hydrophobic filter membranes will not wet with water initially, but with the addition of IPA initially it prewets eg PTFE or PVDF and then allows water to displace the IPA and flow without the classic high (2 Bar) bubble point being generated at the interface of the tightly woven polymeric material. Hope this helps as it is very good lab cheat method of wetting the almost unwettable. Caustic solutions like detergents also may demonstrate very low IFTs (interfacial tension) with other substances, forming very stable emulsions in oils and so forth. RD.
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When the surface of aquarium water is disturbed, the rate of gas exchange between the water and the air is increased; more carbon dioxide is released into the atmosphere and more dissolved oxygen is taken by the water. The surface tension of the water must be broken for sufficient gas exchange.
Fortunately, creating surface agitation is easily done with aeration, or pumping air into the water so that it forms bubbles. The bubbles rise to the surface and burst, thus breaking the surface tension.
