I am trying to prepare an antifoaming agent which consists of a mineral oil (a), aluminum stearate (b), and a mineral oil-soluble emulsifier (c). Here the problem is: When I store the mixture at least for 1 month, some of the ingredients start to precipitate increasing the viscosity which avoids pumping of the agent during the industrial operation. How can I increase the lifetime of the antifoaming agent by eliminating the drawback caused by the abovementioned precipitation problem ?
Emulsified defoamers are es a kind instable emulsions and makes many chemists like me, grey hairs.
To improve stabilty, same dispersing aid like sodium naphtalene sulphonate and also
thickener like CMC, carbomers, xantane gum, often in combination.
Viscosity on the final product between 800 to 2000 centipoises is fine,
good luck Roland.
Dear Roland,
I appreciate your kind answer. You're totally right in that emulsified defoamers make many chemists grey hairs, and I've begun including into this category.
The only agents we've been using to generate an emulsified defoamer are a base oil (a), a hydrophobic dispersing agent (aluminum stearate) (b), and an emulsifying agent (c). I could not understand why you aim at increasing the viscosity of the final product. An increase in viscosity could be undesirable since it could avoid pumping the reagents within a typical process scheme. Hence the typical viscosity of our emulsified defoamer is in the range 70-90 cPs at 20 degrees Centigrades. On the other hand, I read from the scientific literature that increasing viscosity of an emulsified defoamer decreases the risk caused by the sedimentation of dispersing agent during storage. So maybe I should increase the overall viscosity of the product a little bit more but 800 - 2000 cPs sound me too high. Do I think correct ?
Akin, wellcome to our grey hair society, you are right on make the emulsion a little thicker.
Here in Mexico, the users still likes the higher, the better products.
On the other side, the thickeners like CMC, xantan gum as colloids helps in the stabilty, xantan gum the best in our products.
Wy not going up from 70 to 90 cps to maybe same 150 to 200 cps, this should not comprise the pumpability.
Dear Roland,
Thanks for your answer. What is the typical amount of xantan gum which could be added to improve the stability of an emulsified defoamer ?
Another question of mine: Sodium naphthalene sulphonate acts in the same way as aluminum stearate works in an emulsified defoamer, or it is advisable to add it in combination with the metal soap to improve the emulsion stability ?
Akin, 2 questions:
1. xantan gum mostly 0.05 to 0.2 % weight emulsion
2. sodiumnaftalensulfonate helps in dispersing same bad dispersed Al-stearate.
Btw. Al stearate here in Amerika has 3 tipes, LG low gel (to me best, MG medium gel and HG high gel
Thank you, Roland. So I understand that sodium naphthalene sulphonate is added in combination with aluminum stearate to improve its dispersion stability. I should also check if there is another type of aluminum stearate with a lower gelling potential in our market. If there is any, it could work very well for our issue.
I am confused about adding naphthalene sulphonate into the aluminum stearate-in-oil solution though since naphthalene sulphonate is more soluble in water than in oil, and hence, it could decrease solubility of aluminum stearate in mineral oil instead of increasing it. Our intended product is composed of 100% oil.
hai Akin Karci , did you know how to make anti-foaming agent such as Simethicone (polysiloxane group compound) in liquid detergent not separate again after storage? Thank you. I have this question from my lecturer to solve
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