Amirali Masoumi

If you prepare a foam from sodium dodecyl sulfate, and then add dodecyl isothiuronium chloride to this foam solution, then as a result of ionic and hydrophobic interaction, a water-insoluble complex is formed. The foam disappears.

You have to distinuish beteww de-fpam and anti foam. Antifoams prevent the formation of foam, de-fpamerseliminatethe foam onceis formed. Yo prent foam formation onr option is to use low foaming surfactants. These are generally hydrophobic surfactants that are unsyable at the bubble air/liquid interface, whixh is easili disrupted. Alternatively it is possible to use anti-foamers, thataezeither olatir compounds tahtagain de-stabilizes the interface byevaporating, or again hydrophobic surfacyaysntha co-micellize with the other surfactatsand limit the amountof suractant at the interface or settle atthe interface disruptinthe adsorption of the foaming surfactants. De-foaming agent(those whp eliminate the foam once fprmed) workbydisplacing hr othrt durfacyantd ftom the inetrface.

In any case foam is eliminated whenthe interface is fragile and is disrupted as bubbles collide becase of brownina motionot

Yuri Mirgorod

Thank you for your clarification. Overall, I want some explanations about the different effects of surfactants. In other words, surfactants have some effects such as wetting and emulsification. I would like to know how surfactants affect the effects mentioned above. I would be glad if you could introduce references to my problems.

Amirali Masoumi

Foams are different. Therefore, the theory for removing them also varies. I gave one example earlier. More examples can be found in these links.

https://patents.google.com/patent/US4071468A/en

https://patents.google.com/patent/US4071468A/en

https://www.coalitionbrewing.com/what-is-defoamer-used-for/

Surdactants are unique,in that there are species that produce an effect (for example wetting)abdthere are species that cause anti-effect.TI am not aware of a single publication summing the matter, Butthere is a Surfactants Series ( I cannoy rememberbthe editor, but try CRC Press) thar reports nonionic, anionic and cationic surfactants, and describe the effects.

Yuri Mirgorod Guido Bognolo

Thanks for your answers

mostly, as Guido seems to wanted to express, defoamers adsorb strongly at the air water interface and in some cases displace other surfactants, while the defoamers have low ability to form stable lamellas.