Ok,
I have a batch of oil that needs the acib/base process. It titrates at 24ml + 7g KOH ( ouch 31g/l). I think this is too high for base only processing.

I understand the 100ml methanol and 1ml H2SO4/ liter to start with. then I need to wait 1-4 hours and check the titration again. Ok lets say its still too high. Do I just add more H2SO4 to the mix or do I need to mix the additional H2SO4 with methanol? The processor is a closed setup.

Ok if the titration is the desired value do I have to start the base process immediately or can I wait?

-dkenny

Myself, I bought a fryer oil filter off of ebay and plan to filter my WVO with magnesol to remove the FFA's before making biodiesel.
Terry

dkenny, the most accepted recipe suggests the amount of H2SO4 to use should be equal to 5% of the amount of FFA present. I think there may be some advantage in adding the acid slowly or in several small parts rather than all at once. After addition of acid is finished you will need to continue heating and gently stirring for at least 5 hours. Continue until two tests give the same result.

dkenny,
If you follow this procedure, you will get good results.

Terry,
I don't think you will get the magnatude of FFA reduction that you hope for from the use of Magnasol or Dalsorb. You might want to check w/ the factory tech/sales reps. Good luck though!
Diff

Thanks for the help.

just to make sure I got this right before making a mess.
titration using 0.1% KOH is 24
use 500g of oil
the math is
%FFA = 24 x 0.546 -> 13.104%
500g x 13.104% = 65.52g FFA
65.52 x 2.25g = 147.42g methanol
65.52 x 0.05g = 3.276g H2SO4

does anyone know what 147.42g methanol is in ml?
and the same for H2SO4 ?

does this look right?

-dkenny

Your calculation of the FFA % and amount of H2SO4 is correct. The amount of methanol seems high. It is more than you would use for the base stage. Say you were going to use 250ml methanol per litre in the base stage this would be 125ml, then if you used 60% of this in the acid stage it would be 75ml.

The density of methanol is 0.787 and of 98% sulphuric is 1.836.

Don't forget to add the sulphuric to the methanol and not the other way round.

neutral,
So during the acid stage the amount of methanol is not as critical as the amount H2SO4. just as long as there is some reasonable amount. Like you suggested.
tomorrow if I get time I try it

-dkenny

You could use a bit more methanol in the acid stage but you need to have sufficient left over to easily dissolve the KOH for the base stage. I've never tried the reaction with such high FFA oil but when the esterification nears completion you will have a mole ratio of methanol to water of about 10 to 1. If the affinity of methanol and water for the FFA is equal you would get equilibrium at about 90% conversion. I don't know the relative affinities and suspect water has a slightly higher affinity which means a slightly lower conversion. This oil is probably about as bad as you would want to go in a single acid stage process.

dkenny
excuse my brevity. I've got about 30 seconds.
Did you note the relationship of AV to % FFA in the KO's (ISU) recipe?
Your results looks about right at first read.
Dont worry about "making a mess" of a 500ml lot.
That's what 500ml lots are for.

It has been mentioned here that biodiesel production is an excercise of methanol management.
For experimental batches, to learn the processes, no harm done to pocketbook nor planet, draining from a seperatory funnel or boiling off excesses of methanol from 1/2L WVO lots.
But as soon as you see that this method works well, and you begin to scale up your production, you will turn your mind to methanol recycling.
One can work wonders to WVO w/ enough methanol.
For example: take the same WVO that you used above, and "wash" it violantly w/ an equal part of methanol.
When the two have seperated, measure the Acid Value of your WVO.
Do this a few times, sequentially to the same lot of WVO.
In the end you will have WVO w/ the same AV as virgin VO, and a LOT of methanol.
What does one economically do w/ all that methanol which is mixed w/ a miniscule amount of FFA?
Please share your results.

neutral,
As always, thank you.
Diff

The Diff,
Yes I did note the relationship. I used a different method to arrive at the FFA number. In another post Neutral gave the relationship between FFA and titration nubmer using the common standard of 0.1% KOH. He might have also included NaOH as well. I'd have to check.. Making a mess with 500g sample is not my big concern. its the 160+liters sitting in my reactor waiting for me to understand how the acid/base process works so I can make BD out of it. too much to do and not enough time...you might think only people with jobs have this problem, but no I the boss and I have this problem...and I need to get more OIL!!!

at the moment I cannot make enough BD to meet my needs even thouth I start with 200+liter of oil in a batch. just to be fair most of my current oil is considered "BAD". I use to think that a titration of 18 was bad until the last batch that measured 24 + 7 base for KOH in both cases... way too much KOH. also I think the yeild is lower..

I have a setup that my Dad used for transfering propane from a large tank to a small tank to play with for methanol recover. time will tell.
the basis is vacuum on the glycerine, compress the vapor, cool thru a cooling coils back into a liquid. for propane to condensate back into a liquid is done only under pressure. I think for methanol I won't need pressure??? More plumbing changes...

ps I the titration is not using phenol red!!! its using phenolpthanline(sp)

-dkenny

Any news, have you progressed at all?.

My oil starts at 3.5 (NaOH) and finishes at 1.5 after about 12 hours using 1ml / litre H2SO4 with 80ml Methanol / litre of oil. No where near as bad as your situation. I can only warn you of the water that is going to be produced in this stage as it will form some soap in the next stage (why is beyond me as there is supposed to be none or litle FFA left to form soap).

Matt

For every molecule of FFA which is esterified in the acid process one molecule of water is formed. So it is already there.

I haven't tried a large batch yet. I did make a 500g sample...and it worked!! the titration after the acid stage wasn't as low as I would have liked but I took the titration number and some more..I forgot the exact nubmers. I am going to male more test batch before making the large batch.
thanks for asking

-dkenny

Neutral, yes I know the bonding of FFA and methanol forms a molecule of water.

My question was rather, after acid esterfication, is there any aftty acid left to make soaps? Mine titrates nicely at 1.5 (several times in fact so I gave up doing this and just wait 12 hours mixing occaisionally) and then use the base catalyst. Having some issues with what appears to be soaps, is this possible to any large extent?

Pardon me hijacking the thread a little but it is pertinent to this thread as it standds in my mind.

Matt

Matthew,
I don't think Neutral will be upset at my answering your question.

With the acid reaction no soap is formed by the FFA. One water molecule is released in the esterification of each FFA molecule, which can form one soap molecule from one oil molecule in the base stage.

With a single stage base process, the FFA is converted to soap, releasing a water molecule, causing a molecule of oil to form a molecule of soap. - 2 soap molecules.

So, there should be half of the soap formed in an acid/base process than in a single stage base process, for a given oil. This will be a significant reduction for high FFA oils.

So here is the big question:
How can the water be removed after the acid stage to reduce or eliminate the soap formation?

Neutral, If I have misinterpreted the process, please educate me in the correct interpretation.

Tony, my experiments have shown that not all the water that is produced or present to start with will form soap in the base stage. I presume the glycerol has such an attraction for it that its availablity is reduced. So you can't calculate the amount of soap by a simple equation. After a prolonged acid stage there will be very little FFA left to make soap but there will be water and acid as you know. All the FFA left makes soap in the base stage and some of the water does. The sulphuric acid is still there unchanged, which is the main thing measured by the next titration. The losses in a base-only reaction can be reduced to about one third in a acid-base reaction but cannot be eliminated when done in this simple way because of the presence of water.

So it makes an intriguing question as you say: how to reduce the water content. There are quite a few ideas. Use a large excess of methanol which will float up and can be separated. Trouble with that is what will you do with the wet methanol containing sulphuric acid in a back yard operation?

Another approach is to accept the losses initially, then acidify the glycerine to release the FFA and trapped esters, separate them and add them back into the next batch and so regain the losses. This might be easier to do in the garage.

Would the use of dessicant materials (accusorb? or other matter) perform this function?

for water removal.
what about using the same setup as methanol extraction?
of course the methanol would come out first. just collect this and add it the base steo methanol. keep extracting and the water should come out.
just theories for me at the moment. I need to build my methanol extraction.

how critical is removing the water?

in my 2nd test batch there's a thin layer at the top.
should this be removed of left in and shaken before doing the titration for the base step?
its colored like coffee with lots of cream where as the bottom is coffee with just little bit of cream. I hope this help since it FTP login failed again.

-dkenny

I have used the 2 stage method on oil that titrated at 12.5 KOH. using 1 ml of acid for 1 ml of oil I was able to drop the titrated level down to 7 KOH.

I did not worry about water. I immediately added the remaining methanol (20% total by volume: both stages added together) and KOH (7+7 KOH per liter) as I would have in a single stage process and made biodiesel. The biodiesel separated out fine, but it did take more washing to get the biodiesel clean.

I'm 5 hours into 200liter batch in the acid
stage of the 2 stage process. Titration has dropped from 20+ to 9mls (KOH). so far so good.

other details
200 liters of oil
5.5-6 gallons methanol. I'll add 6+ gallons in the base stage. for a total of 25%.
400ml H2SO4
temp was 130 F or so ..limits of therometer.. at the start
heat turned off
pump run continuously since turning heat on.
current temp 150F with a pressure of 6psi. even though I released 1 psi in the middle of the processing.
the unit is sealed.
pressure was 0 after adding methanol/H2S04
I'm using an 80 gallon water heater (new 12/04) as the processor.

more later.
I'm hoping that I'll get 5-6 mls for the final titration

-dkenny