I currently have an oil that titrates at 6 with NaOH. I have done the base transesterification with good success but I decided to try my hand at acid esterification on a small scale. I used the Fatta method which was recommended by Girl Mark. I added .5ml to a 500 ml batch and titrated immediately. It titrated at 7 as it should. However after processing for hours (sampling periodically) the titration result did not change. I added an additional .5ml and it titrated at 8 which did not change after 4 hours. I am using Liquid Lightning as my source of sulfuric acid (from walmart). I eventually went ahead with the base step and the batch turned out beautifully (although alot darker than I am use to). Any suggestions??? Thanks!

how much methanol did you use?
at what temperature did you process ?
how long is 'hours'? I had some take 48 hours..
any idea of the purity of the H2SO4?

-dkenny

How did you mix a half liter for hours? That would drive me nuts, especially after measuring a half mililiter of sulphuric acid. Of course, if you are set up with the beakers, flasks, and other assorted equipment, you probably have an advantage over us farm boys with our five gallon buckets and peanut butter jars.

Norman

I used 10% on step 1 (Ac Est) and 10% on step 2 (base trans). So that is 50ml on each step. I processed at temperatures that varied from 48 to 58 degrees C (hard to get my burner to set). I processed it for 3 hours and took samples every 30 minutes to an hour. I have no idea about the purity. I read another post about someone using this brand from walmart with success but I am thinking that it isnt strong enough to drive the reaction foward. I will get a couple milliliters from work and try again.

Stormin,

Yeah it was kinda nerve racking. But it is what I do for a living. I watch reactions all day long as a chemist. I work with batches ranging from 5 mL to 500 gallons. Btw, ebay sells alot of glassware for fairly cheap.

What is Liquid Lightning and what department is it in at Walmart?

liquid lightning is a drain clog remover and it is in the plumbing department at walmart. It uses sulfuric acid to dissolve alot of organic materials. However I do not know the strength of it so I wouldnt recommend using it at this point.

Just add glycerol and mix. Much easier, safer and is a good use for a "waste product". I washed chicken fat that titrated 11 and after two glycerol washes titrated 0.3.

quote:

Originally posted by funnyfidel:
Just add glycerol and mix. Much easier, safer and is a good use for a "waste product". I washed chicken fat that titrated 11 and after two glycerol washes titrated 0.3.

What do u do the glyc wash in..a separate drum..ur reactor tank? Or could i use my dewatering tank for this too?

reactor tank, you're going to put oil into it anyhow. As long as you can remove glycerol from the oil.

quote:

Originally posted by funnyfidel:
Just add glycerol and mix. . . . I washed chicken fat that titrated 11 and after two glycerol washes titrated 0.3.

What mechanism is responsible for the glycerol being able to remove FFA from the WVO/Tallow/Chicken fat?

Do you use glycerol that still contains methanol, soap, water, etc. Or, did you first process your glycerol by, say, methanol removal and/or acid cracking of soap to FFA followed by settling and separation?

Since FFA are not soluble in "pure" glycerol, then how does the glycerol reduce FFA in your feedstock?

quote:

Originally posted by producer:


What mechanism is responsible for the glycerol

quote:

Originally posted by funnyfidel:
Just add glycerol and mix. . . . I washed chicken fat that titrated 11 and after two glycerol washes titrated 0.3.

being able to remove FFA from the WVO/Tallow/Chicken fat?

Do you use glycerol that still contains methanol, soap, water, etc. Or, did you first process your glycerol by, say, methanol removal and/or acid cracking of soap to FFA followed by settling and separation?

Since FFA are not soluble in "pure" glycerol, then how does the glycerol reduce FFA in your feedstock?

Is it not the excess catalyst in the glycerol that saponifies the FFA so that it is removed that way.
If that is the case than I assume there is quite a loss in yield, with saponification there is normally a neutral oil loss as well.

There is a commercial Biodiesel equipment supplier in Austria who supplies a containerised module that does just this. They take the G phase from the transesterification and add it to the high FFA feedstock and basically remove the FFA as soap, the only down side is the yeild is crap and they have now contaminated what could have been a saleable g phase with soap and neutral oil.

Who the hell know how it works, it just does. No purification of glycerol, just bung it in with the oil, mix it and there you have it.

How do you dispose of the waste glycerol after this procedure?
What kind of yield do you get?
Thanks,
DD

quote:

Originally posted by fireinthelab:
liquid lightning is a drain clog remover and it is in the plumbing department at walmart. It uses sulfuric acid to dissolve alot of organic materials. However I do not know the strength of it so I wouldnt recommend using it at this point.

I don't know the strength either but I use it with great results. (180L & 265L batches) I first made a test batch with 15% methanol and 1.1ml acid to 1L oil. Added acid direct to oil heated to 60C slowly, then mixed.

Killed heat (open top tank) them added the methanol and mixed with a sheetrock mud mixer and a drill, with a fan blowing the fumes away from the drill motor (could be explosive!). Started pump, covered & continued to stir once/hour or so, vigorously.

Titration (NaOH) drops 1 point/hour. Latest batch started at 10.25 & dropped to 6 in four hours. Reheated to 50C, stirred and left over night with no heat or pump on.

Next day (+ 14hrs from start) titrated at 2.5.
First 180L batch started @9.0 and ended at 2.0 with virtually same treatment. All using Liquid Lightning ___% acid from Wal-Mart.

If still in doubt, do a test batch. If it goes south, no biggie. That's why we do a mini brew...

PS From what I'm seeing, it seems the extra 5% methanol speeds up the reaction vs. 10% initially and the methanol supposedly increases the yield/quality of fuel.

Greetings,

I have been doing chemistry research on Biodiesel for 4 years now. I have done some kinetics studies on the effectiveness of the acid catalyzed method and have found it to not be as "good" as it is advertized to be. I will be glad to share the paper I wrote and all of my data. They guys at journeytoforever.org totally rejected it, but they aren't chemists I guess.

I have found that the acid catalyzed method doesn't eliminate all of the FFA in the waste oil, but it does reduce it. I am (as I type) at a biodiesel facility that I am the consulting chemist for and I am trying to work out a method for some oil that was purchased...it titrates at 33 mL. (I'm using KOH instead of NaOH, but the stiochiometry is the same the way I have it mixed) I have found that the acid esterification method is effective in reducing the amount of titrant by approximately 6-8 mL when it is cooked for about 2 hours at 60'C.
If you dont' see much in the way of results after the first hour, I would say there is a problem with your H2SO4 because that is the time where the most of the reaction occurs.

Hope this helps some, I'm glad I happened across this forum..now I have another one to keep up with !!!!

www.plant-diesel.com

Richard A. Smart
University of Arkansas
Fayetteville, AR
Peng Group

analyticalchemist,
have you tried plotting the titration values for the acid stage over time? I guess that the majority of titration drop is as you said, but the titration continues to drop. the rate of the drop slows down, I think.

33ml is bad oil. good luck. my quick calc of the amount of H2SO4 is 6ml/L of oil using 12% methanol by volume, but I never tried this on oil this bad. I still wonder what the upper limit of my quick calc is? also I don't drain the mix between the acid and base stages.

what effect have you seen of water on the acid stage?
at times I haven't gotten the results I expected and suspect the oil contained more water than I thought.

I'm sure this board would like you share your results.

-dkenny

Just thought that I'd add my findings re acid-base. I tried running a 1L mini-batch, my oil titrated at 13.5ml NaOH and I used 10% methanol mixed with the required H2SO4 (lab grade). I ran it for 18 hours (my mini batch processor uses a 3kg lpg cylinder with a stirrer on a shaft powered by a small motor). After all this time, much of it at 56-60deg C, it only reduced the FFAs to ~11g. Rather disappointing.

I then worked up the courage to try a 50L batch in my Appleseed reactor. I ran it for 4 hours and the result was 1.3g NaOH which was plenty good for me. The oil was the same in both cases - canola, with no water content (I get it straight from the fryer).

I believe the difference was the agitation - my main reactor uses a pump that can shift up to 90L / min, and as you are only adding small amounts of acid, thorough mixing is essential. I now introduce the acid at about 45-50deg C as my pump will raise the temperature of 100L of oil by about 2deg/hr.

dkenny - isn't 6ml of H2SO4 / L oil too little for 33ml oil?

Shane
Wellington, NZ.

nzumimogger, I don't know for sure. I've never used oil that bad. but I have used my quick formula with oil upto 20KOH. you can bet that if I had some oil that bad, I'd start at 6ml it might take more??

-dkenny

quick formula
(titration using KOH - 3)*0.2ml/L = amount fo H2SO4
for NaOH use 0.28ml/L instead of 0.2 -> I have never tried this so your on your own...

dkenny

Where did you get your quick formula from?

The following is my interpretation of some posts by nuclear a couple of years ago. I could use a simple conversion of 0.193ml H2SO4 per ml NaOH titrated: => 13.5ml oil requires 13.5 x 0.193 = 2.6ml H2SO4 / L WVO. This is a bit less than the number you are using, but the original theories may have changed over the last 2 years (like 3g to 5g base catalyst).

How I got to the above (courtesy of those who know immensely more that I!):

My WVO titrated at 13.5ml NaOH.

1L WVO = 920g (this is an approximation as it assumes WVO specific gravity is equal to that of oleic acid
SG oleic .914-.920 @ 25 deg C)

Note that the formula contains 28.2 which is the molecular weight of oleic acid divided by ten. Oils are not made of only oleic acid hence this formula results in small errors, normally accepted. The range of molecular weights encountered in the used oil trade is from 270 for palm to 281 for canola.


The FFAs in Canola Oil are approx. 75% oleic acid)

So if my oil titrates at 13.5g NaOH, then the % FFA can be calculated as follows:

0.766 x 13.5 = % FFA

FFA Content = 10.34 %


To neutralise the FFA content we add H2SO4, the quantity being 5% of the FFA by weight. So, converting the quantities to liquid measures ....

Weight of FFAs = 920g x 10.34 %

= 95.13 g

Weight of H2SO4 Required / L = 95.13g x 5.0 %

= 4.8 g / L

Converting to liquid measure = 4.8 g / 1.84 SG

= 2.6 mL / L WVO

where SG = specific gravity of H2SO4

Therefore, for 50L of WVO, H2SO4 required would be:

= 2.6 mL x 50 L

= 130 mL
(or 260ml / 100L WVO)

Add the acid to the methanol. CAUTION: this is a violent reaction.

I've had good results at reducing the FFAs to about 1%, but as I said, I don't have water issues.

I had some oil that titrate at 128.5ml. I treated it for 1 hour at 60C with 2% sulphuric acid, 4:1 methanol and got to 28ml and 3ml after a second treatment. I finally treated the oil with 20% glycerol and it titrated at 0.7ml. I do not seem to have any problems with acid esterification, however, I am looking at solid acid catalysts to use. Any ideas, Amberlyst 15 is supposed to work.