Surfactant

[TidalPete]

I have five litres of 70% Phosphoric Acid on hand & want to add a food-grade surfactant of some description.

Need to know ---
1 -- The name of a decent (non-foaming) food-grade surfactant
2 -- How much to add to five litres of Phos
3 -- Where to purchase a small quantity if that's possible?

Any help greatly appreciated.

 

[labels]

Sodium Dodecylbenzene Sulfonate

 

[Lyrebird_Cycles]

If you insist on low foam*, IIRC all the Tweens would fit the bill but they are expensive because they are mostly available in lab grade.

If you can relax your foam requirement, buy some sodium dodecyl sulphate 70% solution here , take 2.3 litres of it and add 0.75 litres of water then add your 5 litres of phosphoric to the mix slowly. You will end up with a mix of 50% phosphoric and 15% SDS***.

* since the primary effect of a surfactant is to lower interfacial energy, a "no foam" surfactant is an oxymoron. See here for why.

** wear glasses, use gloves. Phosphoric causes lovely third degree burns, I know this from personal experience.

*** I know this doesn't look like it adds up: remember that 70% phosphoric has a density of about 1.53

 

[MHB]

If you add it too fast it will look like snot - and have about the same consistency.
Personally I hate dodecylbenzenesulfonic, what they use in StarSan and don't think of it as no rinse.
The unbranched surfactant like SDS are better, probably a lot more biodegradable and do less harm to beer, still not no rinse!
Mark