Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: julianf on September 24, 2015, 09:15:10 AM
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I did a test yesterday -
500ml of SVO
2.5g of naoh (ie 5g / ltr)
50ml of meth (ie 10%)
The amount of meth would never push the reaction to full conversion, however, its the amount i use for S1 in my WVO conversions, so i stuck to what i was familiar with.
Ran the reaction, but what is now confusing me is that something has clearly happened, but not what i expected.
I have a solution now that a clear layer on top (methylester / triglyceride mix, i expect) and more like a sediment phase on the base.
The interface between the two is much more like a precipitate sedimenting out, rather than two liquids, however, the volume split is about what i would expect.
Also the lower phase is light, more like soap, not the dark brown that i expect at all.
The oil was SVO, from an unopened bottle.
The meth was from a lab - the bottle says <0.2% water (which actually sounds worse than what i buy for bio, but i guess 'less than' does not mean 2%)
The caustic was also from a lab supplier. Ive not looked at the specs.
If it is just soap, i would have thought it to be soluable in the upper phase, but, i guess, possibly not, as the reaction would have been meth limited.
Ive not yet done a 90/10 on the product.
My main question is -
Does SVO produce brown by-product, or white? (pure glycerol is, of course, a clear, colorless liquid)
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New oil certainly produces lighter coloured glycerol. I also notice that when processing at ambient the glycerol is much lighter than when at temperature.
As you have used the methanol starvation method for S1 (which I also use) I wouldn't be suprised if what you are seeing is an excess of di/monoglycerides as the lower phase.
New oil does indeed produce dark glycerol that almost has a pink tinge to it. carotenoids perhaps?
0.2% water (max) in your methanol is 2000ppm you mentioned 2%?
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Ahh, Julian's first ever Dr Pepper ;-)
When I did similar, back in 2008, the glyc. was the colour of honey.
I'd add a touch more meth to bring it up to 12.5% / 13% and see if better separation happens, effectively a single stage recipe.
5g/l is possibly overdosing the base on new oil, which may hinder things too.