First and foremost I see a lot of people doing the Acid Esterification wrong. It should only take 5 to 10 minutes for Acid Esterification and the oil shouldn't be darkened. Most people posting on this forum is not using enough methanol or acid. Per liter of oil, one should use 4-10 liters methanol and 5 to 7 ML 98% sulfuric acid. It takes me 5-10 minutes to convert 100% FFA to bio-diesel without darkening the finish product.

1. Add 7ML per liter sulfuric acid to 4-5 liters methanol.
2. Mix this acid solution with 1 liter Oil (FFA)
3. heat to almost boiling
4. use extreme Agitation for 10 minutes
5. let settle for 5 minutes
6. drain off your oil and reuse methanol for your next batch of FFA-OIL


Now I will try to explain why this method is better. With the excess methanol, this eliminates the water issue. First of all during Esterification any water created doesn't cause a problem. Second, you can even start out with wet oil and it still works very well. You can reuse this methanol-acid mix over and over. To dry your methanol just use magnesium sulfate (epsom salt). You can even mix the magnesium sulfate right in with your batch but I dont do it this way. I can use the methanol acid mix about 5 times before having to dry it. Magnesium sulfate works very well to dry methanol. Magnesium sulfate is also recycled by heating to 450F 10-30 minutes . This removes the water. This method works so well you can even use it to dry your wet oil for the next (LYE Methanol) step. When doing the Exterification step with excess methanol the water is goes into your methanol which is easy to dry.

Depending on how wet your oil is you might not be able to used your Methanol acid solution 5 times like I do. You may have to dry it more often depending on how wet your oil is. Using 4-5 liter methanol to one liter oil prevents the acid from attacking the oil or garbage in the oil making it dark. When you start the next LYE methanol step keep in mind your oil probably around 5% methanol.


In some of my studies I used bars of soap. I shredded them up and dissolved them in water. Than I added sulfuric acid which converted the soap into 100% FFA. This was than dried and I added the methanol acid mix and heated to a near boil. This was put in a blender which was turned off and on ever 30 seconds, the on cycle being 5 seconds. In 5 minutes the Bio-diesel tritration was 1.2. I than removed the methanol from the Bio-diesel. The Bio-diesel was almost as light colored as bio-diesel made from new OIL. Since it started out with 100% FFA it was converted to Bio-Diesel using only acid Exterification. For me, the higher the FFA the better. 50% FFA = 50% less lye I need in the next Lye methonal step.

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The above method can be complicated and a little dangerous and was designed for pure FFA

I am not going to argue with anyone on my first method but rather post a better and safer method. We have 100% FFA and what I posted the first time worked well for me. but for most people the below will work better.
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Recently i found a far better and safer way for high FFA oil. Here is a scaled down version. Use one liter OIL and one liter methanol. Put in 10 Millimeters of sulfuric acid in the methanol. Mix the methanol and oil together. seal the lid. Keep at room temperature and let set for 48 hours. At this point the Titration should have dropped very low. Low enough to process into Bio-diesel. Using.Using 2 liter methanol even works better especially for 50% or higher FFA oil. I was shocked that oil didn't need continued mixing or heat. This method is cheap and safe because you don't need heat and you can use your methanol over and over again. A 55 gallon drum will allow one to process 25 gallon every 2 days with hardly any work and no need to keep an eye on it.
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

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

Samual, some interesting reading here! for 1 ltr lab type batch this process works for you. Now lets upsize to 160 ltrs of oil, are you suggesting that would require up to 800 ltrs of methanol and 1120ml of acid or did i not understand the process.
Do you concider the darkened oil a problem? My oil will be conciderably lighter if I mix the methanol with the oil then add the acid. I have a big problem with mixing the acid into the methanol first, the reaction can be extreme and the fumes given off are said to be very toxic.
The more heat you add to this oil/methanol/acid mix (our method) the faster the reaction will be. It is very possible to complete the process in one to two hours but wet oil is for sure a problem as is the water produced during the reaction. You are very correct in implying that the more methanol used the less likely water will be an issue.(this greatly increaes cost unless one can reclaim the methanol for reuse) Also I find that your suggestion that epsom salts can be used as a drying agent very interesting. Epsom salt disolves in water, what happens to this ingrediant during the process and is there any residual in the biodiesel?

quote:

Originally posted by Biotom:
For 1 ltr lab type batch this process works for you. Now lets upsize to 160 ltrs of oil, are you suggesting that would require up to 800 ltrs of methanol and 1120ml of acid or did i not understand the process.

You math is correct. Keep in mind though you will continue to use the methanol-acid mix over and over again. I am working with micro controllers so its more automated. I am able to use a small tank. X amount of Oil is pumped in and agitated for X amount of time and pumped back out and new batch oil pumped in. This cycle goes until five batches are completed. Its true though for some this might be more difficult. When using this method water is seldom a problem. If heated and agitated properly several small batches can be done very quickly. The oil also settles out fairly fast.

quote:

Do you concider the darkened oil a problem?

For selling it, yes its a problem.

quote:

My oil will be considerably lighter if I mix the methanol with the oil then add the acid. I have a big problem with mixing the acid into the methanol first, the reaction can be extreme and the fumes given off are said to be very toxic.

Yes there is a reaction when acid is added to methanol. I am careful not to pour too much in too fast. You dont have to do this very often since you will be using the methanol-acid solution over and over. With each batch you will lose a little methanol and eventually you will have to mix some more. Acid needs to be put in slowly. If I am not badly mistaken when Sulfuric acid is mixed with methanol it does not form a new chemical compound so the fumes should be methanol and possibly and very small amount of Sulfuric acid. I believe the Sulfuric acid has a stronger bound for water than the methanol so the methanol shouldn't be taken the 2% water away from the acid causing it to fume off. If this is the case than the fumes should only be methanol which isnt that bad.

quote:

The more heat you add to this oil/methanol/acid mix the faster the reaction will be. It is very possible to complete the process in one to two hours but wet oil is for sure a problem as is the water produced during the reaction. You are very correct in implying that the more methanol used the less likely water will be an issue.

Yes you are correct. Water is created during this process but with the excess methanol its not an issue even if you start out with wet oil. I used to use 2-3ML acid to 1 liter methanol for 10 dry liters of oil and still had a big problem with water. It also took forever and the finish product was very dark and i couldn't get the tritration lower than 3. When using proper heat, hard agitation and the excess Acid and methanol I can complete batch in 5 minutes and get the titration down to around 1 even when starting out with 100% FFA. I have read some commercial processes using 10 liter Methanol to one liter oil.

quote:

Also I find that your suggestion that epsom salts can be used as a drying agent very interesting. Epsom salt disolves in water, what happens to this ingredient during the process and is there any residual in the biodiesel?

Epsom salt is highly soluble in water and only slightly soluble in methanol and glycerol.
Epsom salt has a stronger bound for water than Methanol so when put in Methanol it pulls the water out of it. The only way it would devolve in the water and mix in the methanol is when not enough enough Epson salt is used. Other than this a small amount will dissolve in the methanol. If the finish product(bio-Diesel) isn't washed with water you will probably have a very small amount of Epson Salt in it. When you buy Epson Salt from Walmart or most chemical company it will normally be crystallized and contain 15% to 20% water. This is useless for drying your methanol. The water needs to be baked out of it first before using it as a drying agent.

I forgot to mention. During the Lye-methanol step water greatly reduces the yield far more than most realize. Its not hard to lose 10-20% of your product because of water.
So when doing the acid exterification with excess methanol and than removing it you are dewatering you oil. This alone is why its so important to use excess methanol during the acid exterification step.
I notice when I first started out and was only using 1 liter methanol to 10 liter oil during the acid exterification step the methanol would get so wet it'll settle to the bottom of my tank when normally the oil should be the one that settles to the bottom. I left this methanol and water in and of course got reduced yields. Even if one would start with dry oil, the acid exterification step produces enough water that its important to remove it.

well you are certainly right about water from AE reducing yields. my solution to this is to recover ffa (and fuel) from glycerin and wash water. some goes back into AE (all of it if i get some good oil) the rest is blended for use in furnace, stove, old vehicles.

this process isn't likely feasible for any small producers. you would need an enormous AE tank and an enormous methanol recovery unit. but you're right, i'm sure it's how many of the large producers would do it.

Samuel; From Wikipedia- Fisher-Speier Esterification- The reaction was first described...in 1895...Typical reaction times vary from 1-10 hours at 60-110 degrees centigrade. You wrote "When using proper heat, hard agaitation and excess acid and methanol I can complete batch in 5 minutes..." Are you saying that with 4-5 litres methanol, 7 milliliters concentrated sulfuric acid, 1 litre free fatty acids, heating 65 degrees centigrade or so, that you convert ffas to biodiesel in 5 minutes?

quote:

Originally posted by WesleyB:
Samuel; From Wikipedia- Fisher-Speier Esterification- The reaction was first described...in 1895...Typical reaction times vary from 1-10 hours at 60-110 degrees centigrade. You wrote "When using proper heat, hard agaitation and excess acid and methanol I can complete batch in 5 minutes..." Are you saying that with 4-5 litres methanol, 7 milliliters concentrated sulfuric acid, 1 litre free fatty acids, heating 65 degrees centigrade or so, that you convert ffas to biodiesel in 5 minutes?

Yes. But this is using a blender. Normally one doesn't agitate near this hard so it will take more time.
When I was using the blender I wasn't doing a full liter. But the ratio was the same as you mention above. When using 100 gallon tank it takes me much longer as I don't have a way to agitate it as hard as I do when using a blender.

I was shocked when I did a titration and it titrated out to about 1.2 1.5. in such short time. I than left this same batch on for several hours and couldn't get less than 1.2. I dont know why but making a guess it could be the methanol with sulfuric acid that IS mixed in WITH the oil. If I remove all sulfuric acid maybe it will titrate to below 1. Converting pure FFA to bio-diesel is cheaper and Faster than using brand new oil and lye stage. With this in mind i am going to try to pressure cook my oil with water in hopes to convert it all to FFA. This way I can skip the lye stage which is costly and time consuming. I got plenty of wood for a heat source so my cost will be low.

quote:

Originally posted by andyman:
my solution to this is to recover ffa (and fuel) from glycerin and wash water. some goes back into AE (all of it if i get some good oil) the rest is blended for use in furnace, stove, old vehicles.

You 100% right. Anytime you lose some of your product to soap its not a permanent loss as long as you know how to recover the soap. Little bit of good old sulfuric acid put in the waste glycerin and your wash water convert the soaps to FFA which floats to the top. FFA burns good and is easy to convert to Bio.

your putting methanol in a blender ?!!! is your life insurance paid up

Samuel; Part of what you wrote was "the fumes should only be methanol which isn't that bad". Well, did you know that as little as 10 millilitres of methanol can cause permanent blindness in a person. 40 millilitres or so can cause death. When doing chemistry it is a good idea to look up toxicity information on the chemicals you use. Breathing in methanol fumes is as bad as drinking it. Part of making biodiesel is not breathing in the methanol or biodiesel vapour.

quote:

Originally posted by Samuel:

quote:

Originally posted by WesleyB:
Samuel; Part of what you wrote was "the fumes should only be methanol which isn't that bad". Well, did you know that as little as 10 millilitres of methanol can cause permanent blindness in a person. 40 millilitres or so can cause death. When doing chemistry it is a good idea to look up toxicity information on the chemicals you use. Breathing in methanol fumes is as bad as drinking it. Part of making biodiesel is not breathing in the methanol or biodiesel vapour.

I have read all the MSD sheets for the chemicals I used including methanol. And I agree with you in that its very toxic. But there are some facts to look at. One is, the amount that would be breathed or the amount in the air. Generally this is few parts per million. You would almost have to be huffing it to get dangerous amount or breath very strong fumes for quite a while. In making bio-diesel, the mixing acid step takes but a short time. Even if you get 3 or 4 big breaths of it its not going to meet the toxic level. Another fact a lot of people don't understand. Some very deadly chemicals are not toxic under certain amounts. Methanol is one of them. In fact the stomach produces some methanol during digesting foods. The body readily breaks this down.

According to

quote:

http://www.wisegeek.com/what-i...thanol-poisoning.htm
As little as a couple of tablespoons (about 14-28 ml) of methanol can cause methanol poisoning in children. In adults, two ounces (56 ml) may cause methanol poisoning. Ingestion of methanol is cause for very grave concern and immediate hospital treatment.

Now lets take a look at beers and wine.

quote:

http://www.clawhammersupply.co...shine-make-you-blind

How is Methanol Produced?
Methanol is found naturally in certain fruits and vegetables. It may also be produced as an unintended byproduct during the fermentation process. Spirits distilled from fruits, such as apples, oranges, and grapes, are more likely to contain methanol. Both beer and wine generally contain methanol. Studies have determined that wine can contain as much as 329 mg/L and beer may contain somewhere on the order of 16 mg/L. This makes distilled wine (grappa, brandy, etc.) potentially more dangerous than all grain shine - such as corn whiskey.

Why is Methanol A Concern for Moonshiners?
If wine contains methanol but doesn't pose a risk of methanol poisoning then why is it potentially dangerous to drink once distilled? The difference is that the methanol concentration in, say, 5 gallons of wine, is evenly distributed among the 5 gallons. For someone to ingest a potentially dangerous amount they would need to ingest more than 5 gallons....or 28 bottles!

During the distillation process methanol is concentrated at the start of the run because it has a lower boiling point than ethanol and water. The boiling point of methanol is approximately 148 degrees farenheit, which is quite a bit lower than ethanol (the good stuff). This means that methanol (148F boiling temp) will start to boil before the ethanol (174F boiling temp). This is why moonshiners always throw out the first bit of shine they produce from each run (more on this below).

Keep in mind ethanol is an anti-dope for methanol. So if you are drinking while mixing your methanol acid Mix (Assuming it don't make you careless)you will be able to intake a lot more methanol without be coming ill.


Adverse effects from methanol ONLY occur when the amount that is consumed exceeds the body's ability to metabolize it completely to carbon dioxide and water. The first step in the metabolism of methanol is completed by the liver enzyme alcohol dehydrogenase, which converts methanol to formaldehyde. If the body doesn't need formaldehyde to synthesize other compounds, it converts formaldehyde to formic acid. If this occurs faster than the body can break down formic acid, it can build up and cause methanol poisoning.


Ethanol(drinking Alcohol) is metabolized by the same enzyme as methanol. So when someone comes into the emergency room with methanol poisoning (high blood methanol, high blood formic acid), the way to stop further production of the formic acid is to give ethanol, as the enzyme will preferentially metabolize it, and leave the methanol. This gives the body time to break down the formic acid before more is produced.

I hope that this has cleared up the toxicity of methanol. For the record I don't advise drinking while making Bio-diesel.

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

quote:

Originally posted by Samuel:
First and foremost I see a lot of people doing the Acid Esterification wrong. It should only take 5 to 10 minutes for Acid Esterification and the oil shouldn't be darkened. Most people posting on this forum is not using enough methanol or acid. Per liter of oil, one should use 4-10 liters methanol and 5 to 7 ML 98% sulfuric acid. It takes me 5-10 minutes to convert 100% FFA to bio-diesel without darkening the finish product.

1. Add 7ML sulfuric acid to 4-5 liters methanol.
2. Mix this acid solution with 1 liter Oil (FFA)
3. heat to almost boiling
4. use extreme Agitation for 10 minutes
5. let settle for 5 minutes
6. drain off your oil and reuse methanol for your next batch of FFA-OIL


Now I will try to explain why this method is better. With the excess methanol, this eliminates the water issue. First of all during Esterification any water created doesn't cause a problem. Second, you can even start out with wet oil and it still works very well. You can reuse this methanol-acid mix over and over. To dry your methanol just use magnesium sulfate (epsom salt). You can even mix the magnesium sulfate right in with your batch but I dont do it this way. I can use the methanol acid mix about 5 times before having to dry it. Magnesium sulfate works very well to dry methanol. Magnesium sulfate is also recycled by heating to 450F 10-30 minutes . This removes the water. This method works so well you can even use it to dry your wet oil for the next (LYE Methanol) step. When doing the Exterification step with excess methanol the water is goes into your methanol which is easy to dry.

Depending on how wet your oil is you might not be able to used your Methanol acid solution 5 times like I do. You may have to dry it more often depending on how wet your oil is. Using 4-5 liter methanol to one liter oil prevents the acid from attacking the oil or garbage in the oil making it dark. When you start the next LYE methanol step keep in mind your oil probably around 5% methanol.


In some of my studies I used bars of soap. I shredded them up and dissolved them in water. Than I added sulfuric acid which converted the soap into 100% FFA. This was than dried and I added the methanol acid mix and heated to a near boil. This was put in a blender which was turned off and on ever 30 seconds, the on cycle being 5 seconds. In 5 minutes the Bio-diesel tritration was 1.2. I than removed the methanol from the Bio-diesel. The Bio-diesel was almost as light colored as bio-diesel made from new OIL. Since it started out with 100% FFA it was converted to Bio-Diesel using only acid Exterification. For me, the higher the FFA the better. 50% FFA = 50% less lye I
need in the next Lye methonal step.

Hi,
Found your post last night and made me go straight back to my lab. The process you describe has one flaw being that methyl ester dissolves in the methanol. I run your test in my reactive distillation reactor with oil witch tritration at 60KOH and in just 120 seconds the FFA doped down to .2 (tritration done on sample after spun in centrifuge). Under the right conditions the reaction happens fast.

Testing the methanol and acid mixture i found my methyl esters, and none in the oil. Getting the ester out from the methanol and acid is not cost effective.

The two ways i know is

1.) adding water to the mixture will make the bonds stronger between the water and methanol. Esters float to the top, but the you have all the extra water to remove from the methanol.

2.) Vacuum fraction distillation to split the methanol, water from the reaction, esters and the acid.

I use a different approach, 60ml of 98% sulfuric acid slowly mixed into 350ml of methanol, Be careful when mixing large amount of sulfuric acid into methanol. It produces huge amounts of heat and fumes that you should not inhale even in the smallest quantity. Once the mixture has cooled below 35c add it to your oil not higher the 35c. close to 35c as you can but not 1deg over. mix the oil and methanol mixture until it does not separate anymore. Heat to boiling point and keep it there for one hour and tritate (settle acid and water out first). if your tritation is not below 2 (regardless of what you started with) then your oil was not dry. This process does not tolerate ANY water when you start. If no separation then you did not mix everything like you should have. Now you can run a normal base transesterification if you want. Do a 3/27 test to determine the amount of the non reacted oil.

If you do not which to do a two stage process then leave to react for 8 ours at a boil, condensing the vapor of course. Depending on the FFA's you started with it can be done in less than 6 hours (more FFA's the better, low FFA (Below 12) takes 8 hours. Separate and wash with WATER. Dry wash do not work and i have used them all. They are made for base catalyst.

Getting back to your way, Doing anything less than 100% FFA's is a problem with separating the methanol mixture accordingly.

Do you have a solution for the problem?

-Electromechanical engineer with chemistry as a hobby-

quote:

1. Add 7ML sulfuric acid to 4-5 liters methanol.
2. Mix this acid solution with 1 liter Oil (FFA)
3. heat to almost boiling
4. use extreme Agitation for 10 minutes
5. let settle for 5 minutes
6. drain off your oil and reuse methanol for your next batch of FFA-OIL

ok. I wish I was more active when this was posted.

your using 4-5 liters of methanol per liter of oil..instead of 200ml? or 40-50 times the amount of
methanol..
#3. heat to almost boiling..the methol/acid or the oil. if you heat the oil over 190 you'll never get the methanol/acid to mix in..yes I tried once..don't work..might in a blender scale(1L) but usless in the real world

#4. what's extreme? I run a 2 minute turn on a 65gallon tank..
#6..they're mixed..in 5 minutes with extreme agitation it might not settle..in 5 minutes

and you claim 100%FFA..did you make it?? since I've been making bio I've never seen oil this bad..
grease trap crap is less..ya.been there..and stinks

-dkenny

I am not going to argue my method with anyone. We have 100% FFA and what I posted worked well for me. Recently i found a far better and safer way for high FFA oil. I am going to give you a scaled down version. Use one liter OIL and one liter methanol. Put in 10 Millimeters of sulfuric acid in the methanol. Mix the methanol and oil together. seal the lid. Keep at room temperature and let set for 48 hours. At this point the Titration should have dropped very low. Low enough to process into Bio-deisel.Using 2 liter methanol even works better especially for 50% or higher FFA oil. I was shocked that oil didnt need continued mixng or heat. This method is cheap and safe because you dont need heat and you can use your methanol over and over again. A 55 gallon drum will allow one to process 25 gallon every 2 days with hardly any work and no need to keep an eye on it.

quote:

Originally posted by dkenny:
your using 4-5 liters of methanol per liter of oil..instead of 200ml? or 40-50 times the amount of
methanol..

-dkenny

that is correct. I didnt say before but one must use 7ml acid in each liter.

First of all i am no longer use this method. I posted a newer method that works better.

quote:

Originally posted by dkenny:
#3. heat to almost boiling..the methol/acid or the oil. if you heat the oil over 190 you'll never get the methanol/acid to mix in..yes I tried once..don't work..might in a blender scale(1L) but usless in the real world
-dkenny

148.5 °F is the most you can heat it.. i normally keep it to 135f. even 100f is fine but i didnt know that at the time.

quote:

Originally posted by dkenny:
#4. what's extreme? I run a 2 minute turn on a 65gallon tank..
-dkenny

Blender is extreme

quote:

Originally posted by dkenny:
#6..they're mixed..in 5 minutes with extreme agitation it might not settle..in 5 minutes
and you claim 100%FFA..did you make it?? since I've been making bio I've never seen oil this bad..
grease trap crap is less..ya.been there..and stinks
-dkenny

In a large tank it may take longer to settle.
Yes I make the FFA for testing.

well.. you should also mention that using a blender is DANGEROUS!!
sparks and methanol tend to not get along..ie bang! fire..or BOOM..ever been around a methanol BOOM/
I HAVE..it wasn't fun either..so skip the blender..

so I would suggest skipping using a blender..IE a universal motor mixing device..like BioTom ask is your life insurance up to date?

since 100% don't exist why make them..
it possible to process 80% already..done that..
it stinks..by they way..

now to counter what I've said..
conjecture this..take bad oil..make to worse to the limit..100%FFA..
then process..using AE..many stages of AE..
been there..yea many stages of AE..bang for the buck..burn it..
the return it usable fuel isn't worth the processing effort..

-dkenny

quote:

Originally posted by dkenny:
well.. you should also mention that using a blender is DANGEROUS!!
-dkenny

My blender is sealed up good.

quote:

Originally posted by dkenny:
since 100% don't exist why make them..
it possible to process 80% already..done that..
it stinks..by they way..

-dkenny

90% to 100% is more common than you think. Some companies remove the FFa From the oil before prcess it into bio. IF this is done you will have almost 100% FFA. You batch should not stink. If it does you are not using enough methanol.

quote:

Originally posted by dkenny:
now to counter what I've said..
conjecture this..take bad oil..make to worse to the limit..100%FFA..
then process..using AE..many stages of AE..
been there..yea many stages of AE..bang for the buck..burn it..
the return it usable fuel isn't worth the processing effort..

-dkenny

It is pointless and a waste of time doing many stages of AE. It can be done in a single batch using little heat and little agitation. I do it a different way now. read back on couple of my post and you will see what i am saying.

I am Praniesh, studying final year Industrial Biotechnology in Government College of Technology, Coimbatore. I am currently doing my project in "biodiesel production from mahua oil", the oil has a FFA% of 18. I did two step acid pretreatment using 0.35 v/v and 0.30 v/v methanol and 1% h2so4 to reduce the FFA but i could reduce it only to 4 not less than that. I tried it several times but still couldnt reduce it. I performed alkali transesterification reaction and it resulted in soap formation. So what should i do to reduce the FFA less than 1? should i change the quantity or is there any other alternative method? kindly reply me, thanks..

don't forget to allow for the acid you used, each ml of acid/ltr of oil will result in a titration of about 2 points. so if you use 2 ml of acid/ltr then the lowest t would be 4

You know the acid esterification step, is the Fischer esterification? Where carboxylic acid + primary alcohol + strong acid catalyst plus heat yields the ester? I see no mention of conditions in your acid pretreatment. I did it in a small amount, but with a smaller percentage of free fatty acids present. When the esterification occurs in the reaction of the carboxylic acids and the primary alcohol, water is produced in an equimolar amount to the moles of free fatty acids that become esters. That water being present after the Fischer esterification is a problem for the transesterification reaction, which relies on little water being present. Water decomposes methoxide ion which causes the transesterification reaction to occur.. There is a solution to this problem but it might not be cost effective on a large scale.