Hi,

I have been reading about this acid esterification stuff for a few hours now and I don't really get all the steps that are involved in it? I don't mean to ask questions that have alwready been answered, but too help us newbies and for someone who would like to see it get done, can someone post pics of the process being done?

I have lots of oil that I did not process due to the fact that it titrated really high. And I want to do the acid/base process but just don't know how to do it? So can someone (Grey, dkenny or GirlMark) show all the steps that are needed to do one step at a time (With pics please for us visual people). I know that this will help out alot of people and not just me.

Thank you,
Gab

sorry I've never taken pictures, but the steps are easy

1. titrate the oil
2. use thsis formula to determine the amount of H2SO4 needed. (Titration - 3) * 0.2 = mls of acid needed per liter of oil
3. figure out 12% of the oil volume. this is the amount methanol needed.
4. heat the oil to 140F to 150F. 60C to 65C.
5. pour the acid into the methanol. slowly is best, because it'll boil like mad.
6. add the methanol/acid mix to the oil..
7. stir for 2 to 12 hrs. the easy way to determine when its done is to titrate the mix as it processing. it'll reach 3 or so when its done. if all went well.


Base stage Steps
use 8% to 10% of the initial oil volume for the amount of methanol. plus the amount drained if you drain
if its under 14, use the titration used to determine when it was finished for the amount of caustic needed for the base stage.

if the oil's initial titration is over 14 KOH you'll want to let it settle over night then drain about 1/2 of the volume from step 3.

if its over 18. drain

if you drained, remix and recheck the titration. normally it drops from the ending titration

math example

oil titrates at 25 KOH
60 gallons of oil or 227 liters
25-3 = 22 * 0.2 = 4.4 mls of H2SO4(acid)
4.4 * 227 = 998.8 mls total acid. HANDLE WITH CARE!!!!
12% of 60 = 7.2 gallons of methanol or 27.25 liters
in this case the titration might only drop to 7.
let it settle
drain 3.6 gallons out
remix and titrate..
lets say it reached 3 for the titration after draining

for the base stage using KOH
8g (base) + 3 (titration) = 11g per liter
11 * 227 = 2497 grams of KOH total
10% of 60 = 6 gallons of methanol or 22.7 liters
now if you drained at the end of the acid stage. add that quantity in additional methanol. in this example since we drained, we would use 6 +3.6 = 9.6 gallons in the base stage

mix the KOH in the methanol. use a sturdy container. it will get HOT!!

add the methanol/KOH to the oil. this is same as a single base only stage.

test for 27/3. reprocess as needed...

good luck
ask if you have questions

-dkenny


please use good chemical handling when using this process...H2SO4 is dangerous. it worse when its added to methanol.

Ok that really cleared things up! I will go threw this this weekend and will make a batch when I come back from vacation. I more then likely have some more questions when I start going threw the steps. Thanks for your patience!

Take care,
Gab

dkenny,

re,
...4. heat the oil to 140F to 150F. 60C to 65C...

I don't understand this bit. As methanol boils at 64C why do you need to raise the temp past this point when it wll only cause boiling ?
regards
dva

because pure methanol boils at 64C, but impure methanol doesn't. just like water. pure boils at 212F or 100C but add salt or glycerin at the boiling point changes. oil and methanol boil at a higher temp temp than pure methanol.

ever looked at methanol recover from glycerin? the temp the last methanol boils out is well over 100C.

-dkenny

dKenny,
The used cooking oil I collect averages 3.5-4.5 g/l NaOH (4.9-6.3 g/L KOH) which translates to .25 to 3.1% soap or roughly 1.5-2 gallons of soap per 60 gallon batch. Currently I use the 80/20 base/base method but I am wondering if the acid/base method can be justified with this titration level.
Do you have an opinion on this?
Tx,
Rick G.

You would be wasting money on acid with oil that titrates that low, you are only going to lower it one or two points.

Rick G.

fabricator said it...it would be a waste.n you might look at switching from NaOH to KOH.. KOH is more forgiving at higher titration than NaOH and the GLy stays liquid to a lower temp.

i don't use acid unless the titration is 7 or more KOH..

I'm really happy if I get oil that's less than 7 KOH.

-dkenny

my oil titrates between 6-7 and acid esterification has been berry berry good to me.
my recipe is one i found here (sort of)
30 gals. VERY DRY oil
4 gals. methanol
170 mls. 93% sulfuric
mix meth and acid
feed to heated oil
mix for 12-18 hours
then add:
methoxide made with 2 gals. methanol
28.34 grams Naoh
mix for 3 hours
settle
almost 100% recovery and passes 3/27 easily

quote:

30 gals. VERY DRY oil
.......28.34 grams Naoh

1/4 gram NaOH per liter oil?

Ounces maybe?

What determines acid stage mixing time? Will mixing the batch more vigorously shorten the time?

I believe on my processor it does, I have a pump that will do 95 gpm on a 250 gallon processor and so far my acid stage has taken six hours at most to get as low as it is going to go, I also have an outside the processor heat system so I keep it at 135-140 degrees the entire time.

Make sure the starting oil is BONE DRY.

I know this is probably a dumb question, but is the acid process done in an appleseed prior to the normal process?

Thanks

quote:

is the acid process done in an appleseed prior to the normal process

Yes. Heat to temp, shut off element, then add methanol/acid just like in a normal process. Then either settle and drain or don't settle and drain any water, depending on if your original titration was above or below about 15ml KOH, I think is the number. Then re-titrate and add the methoxide and proceed as normal.

The only dump question is the one not answered because it wasn't asked.

holy moly!
yes provo, ounces.
i think i need a new hat!

Just a quick question. I have just successfully completed my first test batch and my first 20 gal batch using the acid/base process and an appleseed processor.
My question is this:

It took almost an hour to get the acid/meth sucked into the heater. Is this normal?

Every time I opened the valve the acid/meth would boil like crazy inside the heater. My oil was a little hot. 155 f. (My temp gauge went out during heating) Is this normal? I am hesitant to try it again. Any suggestions?

Travis,
the boiling is not normal any chance the temp was higher than that? say 170. also since the acid process is a slow process there is not need to inject it slowly. I use usually dump the methanol/acid in about 5 minutes where the methanol base will take 30-45 minutes

-dkenny

dkenny,

Well I finally got my nerve up to try it again. I installed a new temp. gauge and heated my oil to 140f and added my methanol/acid. NO PROBLEMS! I guess my oil was way too hot last time. It only took about 5 min. to load it into the processor.
Thanks for the help.

Travis

This message has been edited. Last edited by: travislangley,

Uhm, I'm quite confused guys.. what's it difference between transesterification? Is it the process of exchanging the alkoxy group of an ester compound with another alcohol?
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