I added citric acid in my dish washing liquid. It stopped foaming. Iwant my liquid again to foam. because I prepared 4 litres of liquid. Please let me know how can i get back my liquid foam. please answer immediately.
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1$\begingroup$ Any acid is an anti-foaming agent (if you have an anionic surfactant, that is). $\endgroup$– Ivan NeretinCommented Nov 7, 2018 at 7:09
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2 Answers
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Citric acid is not a defoaming agent in itself. It is routinely used for pH adjustment in many commercial hand-dishwashing agents.
But it depends on the surfactant in the product. As Ivan tells, anionics will at some point be protonated by acids, and thereby loose their surface activity –and foaming capability.
Commercial anionic surfactants like ethersulfates will only do so at rather low pH, outside what is relevant for dish-washing products. But if your product is based on saponified oils it’s another story. Many fatty acids are weak acids (pK in the rage of 4-5) and will be significantly protonated at pH even as high as 5-6.
By the way: making good foam is as much an art as a science :-). If you want to dig deeper in the subject, I can recommend “Prof Steven Abbot –Surfactant Science, Principles and practice”. It is freely available on the web.
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If your dishwashing liquid is an anionic surfactant which is protonated by the citric acid, you may have noticed a precipitate of some kind, or perhaps an unusual oiliness. If you can, check the pH.
A possible cure would be to raise the pH to 8 or 9 and stir or shake. Borax should do the trick. Sodium carbonate (washing soda) could work, but would probably give some foam from evolution of CO2, so do it little by little. More alkaline materials like sodium or potassium hydroxide would be less safe for home use because of possible overdosing.
Grease removers are generally not acidic, because most greases are more dispersible/removable with alkaline aqeous surfactants.
answered Nov 7, 2018 at 14:05