Different approach to 'Jelly'.

[DavidA]

I recently over did the NaOH in a test batch. And after it had stood for half a day I noticed no glyc drop out, but a definite jelly forming.

So, I reasoned that as I had messed up the ration of svo to NaOH, I could correct this by adding more svo.

I added a further 100 mL of oil and the jelly has gone away.

Is this an approved method of 'de-jellyfing' bio ?

[dgs]

I recently over did the NaOH in a test batch. And after it had stood for half a day I noticed no glyc drop out, but a definite jelly forming.

So, I reasoned that as I had messed up the ration of svo to NaOH, I could correct this by adding more svo.

I added a further 100 mL of oil and the jelly has gone away.

Is this an approved method of 'de-jellyfing' bio ?

Not a normal method. Can't see that it was a reverse reaction, more that the soap was neutralised because of ffa's in the added oil?

[countrypaul]

Jelly is normally caused by soap, soap is normally formed from neutralising FFA with NaOH. If there is insufficient NaOH (or a high amount of FFA) then there will be soap formation but little transesterification with little resultant glycerol so the soap will remain in the oil making it jelly like. If you use too much NaOh then there will be hydrolysis of the oil (think of creating FFA from the oil) which will neutralise the NaOH and form soap  which can form jelly.  Adding more oil might simply mean there is enough liquid that the amount of soap present does not result in jelly. I would expect this to be temperature sensitive, in that if this was done as a Dr Pepper reaction at ambient temperature a jelly being more likely. Did any glycerol drop out after adding the extra oil?

Any FFA from the additional oil would form more soap with the NaOH (assuming there was some unreacted left) - in order to get a reverse reaction you would need to trigger esterfication of glycerol and FFA - something that would typically require the presence of conc. sulphuric acid (See acid base reaction).

There was a recent thread on ambient processing http://biopowered.co.uk/forum/index.php?topic=3347.msg41017#msg41017

[DavidA]

Paul, dgs,

Just checked the offending test (Dr Pepper, two Litre in a three Litre bottle) and after standing overnight there is about 2'' of bio on top of the remaining liquid. This appears to be darkening as it goes down, so it may be on the point of dropping glyc. I'll add another 100mL oil and see what happens.
Hopefully I won't have to resort to the acid.

[DavidA]

More bio appearing in the bottle. Also some glyc dropping out.

[DavidA]

Just checked the drop-out.

Indicates 3.

[dgs]

so how much sodium did you add?

[DavidA]

I didn't add any NaOH. Just the 100mL of oil that I mentioned above.

[dgs]

Originally, to your 2 litres of oil?

[countrypaul]

Just checked the drop-out.

Indicates 3.

May be me being slow but what do you mean "Indicates 3."?

[DavidA]

Paul,

Sorry, I meant 3mL drop-out.

dgs,

Thanks for the pump, the coffee, and for the opportunity to acquire some bit of glassware.

Re the sample I showed you.
When I got home I drained off the glyc, warmed up the sample  to around 50C, gave it a good shaking and left it overnight. In the morning there was drop-out was now 2 mL drop-out. So the warming and shaking seems to have done some good.

I am assuming that I used 5 G/Litre NaOH in the original mix.
So that would give me 10G for the two litre. Re heated the sample. I mixed 2 Gram NaOH with 20mL Methanol and added this to the original, Now waiting for the drop-out.

Dave.

(note to self. Must keep more accurate records)

[countrypaul]

David,

Different people use different quantities for dropout tests, 3/27, 10/90, 25/225, 30/270 etc. What did you use, presumably not a 3/27!

[DavidA]

It was a 10/90 test.

[DavidA]

I forgot to mention.

After the troublesome sample had cooled down overnight, the glyc dropped out leaving a clear 1.5 litre of bio.

I'll do another 10/90 later and decided what to do from there. I'm a bit leery of adding more meth/NaOH.