Has anyone ever utilized any type of commercially available antifoam for reduction of foaming during methanol recovery?

Good idea, chief. I had thought about using the stuff sold for carpet cleaning machines, but have not got round to it yet.

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Originally posted by David L. Teal:
Good idea, chief. I had thought about using the stuff sold for carpet cleaning machines, but have not got round to it yet.

Hot tub foam killer may work also.

-Jim

Hydrochloric acid should work... kills the foam by desoaping...

If you use the correct amount of acid it will turn all the soaps into FFA. After you have boiled off the methanol you can float the FFA off and put them in the next acid stage, thereby recovering most of your losses and reducing the waste stream. Why don't we all do it?

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Why don't we all do it?

1. Often an acid stage is not needed
2. Water in dilute acid spoils glyc as a burner fuel

Hell, let's do it anyway :-)
To determine the 'correct amount', I suppose one would titrate, but as the glyc is so dark coloured this might be difficult.

Follow the soap test from soap test

You use 0.5 g disolved in 100 mL isopropyl and bromophenol blue indicator. I have been testing my BD and glycerine. I find that my unwashed BD usually has 2000-3000 ppm (depends on the starting FFA) and the glycerine has 10000-20000 ppm soap.

I have been recovering the methanol by distilling it. I have had foaming issues on some of the BD samples (usually doing a acid/base/base method), but that was when the MeOH was almost gone. To my surprise though, I have not had my glycerine foam.

I would guess the antifoam would have to perform well at high temperatures and not interfere with the bp of the solution. I work at a lab with lots of access to equipment and chemicals so I may try it.

I have been distilling the MeOH off from the acid/MeOH layer removed before performing the base stage on an acid/base procedure. I have noticed that the left over liquid separates into two layers. Is this ffa (dark brown, not see through) on top and purified glycerine (looks like dark tea, not as dark as the top) on the bottom?

Yes I think most of the top layer would be FFA. FFA is more soluble than triglyceride in methanol. Underneath that layer would be glycerine and sulphuric acid if you ran the acid stage for a long time, but if for a short time mainly sulphuric acid.