Hello Everyone,

Can any of you experienced BD makers explain what the foam is that appears
on top of the BD while stirring??

Is that the glycerol on top??

BD Batch:
1 litre Tallow
200 Ml Ethonal (pure 99%)
10 Grams of lye (caustic soda)

Stirred in the ethonal and lye
at 135F for 1/2 hour and got about 2 inches of foam on top
of the liquid, is the liquid actually BD??

Any ideas??

Cheers!

Almost everyone on here will be using Methanol, not Ethanol to make biodiesel.

If you are using Ethanol you will most likely need more like 250 ml/litre oil.

Also usually 5 grams NaOH is about the right amount for new oil.

Glycerol will settle to the bottom. The foam may be the actual reaction happening or it could be something that's unique to using Ethanol.

Agree with Qwarla, above, but think you may even need closer to 300ml ethanol for your tallow. Did you premix your ethanol and lye before adding to the oil?

I've had this foam before both when making biodiesel and dry bubble drying.

In the first instance I believe its water, enough to promote soap making but not enough to stop the reaction. Maybe there is a majic number. Also maybe its the level of aggitation thats causing the bubbling.

When bubble drydrying, bubbling can also happen. I've removed this inch or two of bubbles and then its just reduced to fluid. I wont use it though as I believe is more than just biodiesel. I'd like to test it and see what the heck it is.

__________________
Joe Morgan
Brisbane Biodiesel Site Admin
http://www.brisbanebiodiesel.com

Searching tips using Google - SVO Dual tank systems
SVO, Common Rail and Direct Injection - Vehicles converted to Used Cooking Oil

I fully back joes comments as they are identical to many of my eperiences.

__________________
Cheers
Nick.

Roidio 2001 Holden Rodeo 4x4 2.8L TD. 2.5" Straight through exhaust sytem, heat exchanger shower system. 2" Body Lift,
And lots of fruit, B100 for 25,000 no problems.

Elsa 1983 Mercedes-Benz W123 300D. The Fastest Merc in Oz, Loving B100 Burgers

QUOTE (Agree with Qwarla, above, but think you may even need closer to 300ml ethanol for your tallow. Did you premix your ethanol and lye before adding to the oil?)

Yes the ethonal was premixed with the lye and added to the oil
at a temp of 140F.

This is what I have found so far:
Wwith tallow I have tried so many different ways to aviod this foam stuff and have found that to little lye causes the issue, to much lye
makes it into gel.

However I have tried WVO from a local resturant
and I have tried this various times and got foam everytime.

I really don't know what the stuff is, however
with tallow I had good seperation and tried to re-heat
the tallow to make it liquid again as it did harden,
when it liquified again it seemed that the glycerol layer
had boiled through the oil and became the foam.
I scoped the foam off, let it settle again
and had no glycerol layer in the same batch at all.

Maybe it's just glycerol????

Don't know will keep trying to figure it out.

Required ethanol amount would increase by about 45% over that of methanol to have the same numbers of alcohol molecules present in the batch.

Ethanol readilly abosorbs water from the air - more so than methanol. It is possible that your ethanol is 'wetter' than you think. The presence of water would 'poison' the extent of conversion to ester leaving partially reacted oil. The mono-glyceride form of partially reacted esters is used in industry as a surface active agent that can cause foaming and the formation of emulations. Can you perform the 3/27 (Jan Warnqvist's Conversion) Test on your product?

Jan Warnqvist's Conversion Test- Outstanding! (3/27) - Topic Powered by eve community

Cheers

Was the container sealed that you stirred it in? If not, you probably lost a bit of methanol at 135ºF due to evaporation.

What colour is the foam? Is it like a light soapy froth or is it a thick dense yellow/brown substance. Does it form as soon as you add the sodium ethoxide or does it form slowly over time?