I have tried two bathes with unused rapeseed oil - but without success.
The titration did not produced the expected result. The titration, with oil, was simulal to the blank titration ... Instant equalibrium.
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. No separation occured the fyrst 24 hours - it just gelled - like gelatine. After a week it looks like rapeoil on the top 20% down and milkshake from here to the bottom.
Do anybody have an idea why this not is working ??

tom

You didn't say how much lye you used, but 25% ethanol may be low. I've heard you need to use 30% alcohol or so, and more lye per liter as well.

How hot was the oil?

quote:

Originally posted by tomkruse:
. . .
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. . . .

You did not use enough alcohol.

You may not have used enough catalyst.

In round numbers the molecular weight of methanol is 32 gm/mole, and for ethanol is 46 gm/mole. The "target" amount of 25% alcohol is good if you are using methanol. The amount must be adjusted up by a factor of about 44% (46/32 = 1.4375 or 44%) when using ethanol.

So 25% x 1.4375 = 36% ethanol. But! this is for pure ethanol. Since your ethanol was denatured to 93%, then you also need to adjust for the denaturant. Again, 36%/0.93 = 38.6%.

You should have used 38.6% denatured ethanol in your reaction.

Now for the catalyst.

I interpreted your value of "0,1%NaOH" to mean "the amount of catalyst I used was equal to 1/10 of 1% of the weight of the rapeseed oil." A single liter of rapeseed oil will weigh about 880 gm/mole. So 1/10 of 1% would equal 0.88 grams of NaOH per liter of oil. This is not nearly enough catalyst to drive the reaction.

In this case both the low amount of alcohol and the low amount of catalyst worked against your reaction.

If, instead, the weight of catalyst that you used was equal to 1% of the weight of the oil, then 8.8 grams of catalyst per liter of oil would be about right.

In this case the low amount of alcohol was probably your biggest problem.

You also should determine something about the denaturant used in the ethanol. If the denatuarant was regular unleaded gasoline, then the reaction (according to posts found elsewhere on this site) should have proceeded without too many problems, provided the recipe had been correct. Other types of denaturants (I don't know what those may be) may produce an adverse reaction in the transesterification reaction.

quote:

Originally posted by producer:
So 25% x 1.4375 = 36% ethanol. But! this is for pure ethanol. Since your ethanol was denatured to 93%, then you also need to adjust for the denaturant. Again, 36%/0.93 = 38.6%.

Unless it was denatured using methanol.

-Jim

Thank you - all of you.
The 0,1% lye was user for titration only. The amount of pure lye desolved in the 93% ethanol was 6 gram.
I have not bee able to find the denaturation egent but on Wikipedia I found that diethylphthalat is used.
Can this agent disrupt the process ?
Or shoult I only use more ethanol ?

The the oil was heated to well ower 100C but the ethanol/lye mixture was not added before the oil had dropped to 55C - and the ethanol/lye mix was close to 55C also.

There is a slight error in the above calculation. The specific gravity of rapeseed oil should have been accounted for in the calculation.

One liter of pure rapeseed oil will weigh about 978 gms (880 gm/mole / 0.90 specific gravity = 978 gms).

Therefore, 1% catalyst by weight = 9.78 gm (0.01 x 978 = 9.78) catalyst per liter of oil.

You used 6 grams of catalyst (I assume you used one liter of oil). Six grams of catalyst per liter of oil would be equivalent to 0.61% catalyst by weight.

Based on all these calculations you should increase your alcohol volume. You should also consider increasing your catalyst weight, as UFO originally suggested.

I know most of this is extraneous information, but since I made the error I just thought it should be corrected.

ps: Also, if the ethanol denaturant was methanol (good call, Jim D), then the % of denatured alcohol could be a little less than 38.6%.

What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.

quote:

Originally posted by HelpingHand:
What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.

Hehehe, ethanol "denatured" with water is called Vodka

quote:

Originally posted by UFO:

quote:

Originally posted by HelpingHand:
What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.

Hehehe, ethanol "denatured" with water is called Vodka

At 186 proof we call it moonshine in these here mountains.

quote:

Originally posted by tomkruse:
I have tried two bathes with unused rapeseed oil - but without success.
The titration did not produced the expected result. The titration, with oil, was simulal to the blank titration ... Instant equalibrium.
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. No separation occured the fyrst 24 hours - it just gelled - like gelatine. After a week it looks like rapeoil on the top 20% down and milkshake from here to the bottom.
Do anybody have an idea why this not is working ??

tom

Just use methanol instead and you won't have a problem