Here's one posted on the infopop site:


The FATTA method
- Development by Kevin Tidball and Michael Fox

First stage acid catalyst (to esterify the FFA)
Oil 1000ml (1 litre)
CH3OH 100m (Methanol)
H2SO4 (conc. 98% 18M) 1-2ml
React at 48- 54C until titration falls to a minimum hopefully 2.6 ml could take longer than 2 hours. Greater levels of acid will raise the titration end point.

Second stage alkali catalyst (transesterification of the oil)
100ml methanol
6.4grams of NaOH
(3.5grams for catalyst + 2.9 grams for acid neutralisation if titration of 2.6ml achieved)
React at 48- 54C for 1 hour.
Settle and separate

A two step process that always works, but is not fool proof.

Before Acid Pretreatment of High Free Fatty Acid WVO Feedstocks, it is necessary to determine the Acid Value of WVO

Equipment needed:
Sulpfuric Acid, KOH, phenolphthalein, Methanol, High FFA Feedstock
Scale (accurate to 0.01G)
Glass containers w/ tight lids
Acid Value Measurement:
1) Prepare a beaker by adding ~ 125 solvent. Ideal solvent consist of combination of 100% isopropyl alcohol and toluene
2) To the beaker add ~ 2 ml phenolphthalein
3) Titrate the beaker with 0.1 KOH to first permanent pink
4) Add about 5 grams of sample (weigh to get exact amount) to the beaker
5) Titrate the beaker with 0.1 KOH to first permanent pink
6) Calculate the Acid Value (AV) of the WVO from the following:
AV= A x N x 56.1/W
Where: A = (Titration in ML of KOH)
N = normality of KOH (0.1)
W = sample of WVO in Gram
7) % FFA =~~ 1/2 (AV)
Procedure:
1) Measure the AV of the feedstock. Remember that FFA% is equal to approximately 1/2 of the AV.
2) Put 1,000G of the feedstock heated to 140 deg. F in ~2L container
3) Measure out in another container an amount of methanol = to 2.25 g of methanol for every gram FFA in the flask.
4) Add an amount of concentrated sulfuric acid equal to 0.05g for every gram of FFA in the
ALWAYS ADD THE ACID TO THE METHANOL AND NOT THE OTHER WAY AROUND
Procedure (continued):
1) Agitate the methanol/acid mixture until well mixed.
2) Add to the feed stock
3) Agitate at 140 deg. F for one hour
4) Let cool
5) Separate the two layers
6) Measure the AV of the WVO
7) Repeat until the AV value comes close to Virgin Oil Stock:~ 3~4

Then proceed as normal with base transesterification using NOH or KOH amounts determined by titration of the treated WVO.

Note: water is created by this process.
Water stops the process.
Therefore, especially high FFA content WVOs will need to be treated several times to get them from say 90%FFA to AV of 3 or 4.
But generally, using 93% sulfuric acid, I can change the AV of WVO from 14 to 3 in one step.

Thanks for the info. I don't generally have high ffa oils. My sources usually leave me in the 0.5 to 1.0 range. I still would like to increase the yield as I am only getting 90-93% conversion although I think that in the mix there must be some pork fat (bacon from the breakfast sandwiches lol). If that is true the mix of bacon to veggie is about 2.5 or 3 to 1 and could be causing the low titrations. I feel it must be higher but have no proof. Being winter here the fat isn't freezing as lard would so I can't tell which load is which. Any shared thoughts on raising the conversion would be helpful. I'm using KOH at a base of 6 plus titration. Lower numbers seemed to produce more soap in the first wash. Now I have very little soap, easy wash and fast drying not to mention emulsion free, which is an ugly mess.

Thanks again for the help and any help that can be offered is a question away.

Rich D.

Rich, yield and conversion are two different things. Conversion is the percentage of the oil that was converted from oil to biodiesel. Yield is the amount of fuel you get from the reaction.

You can have a low conversion reaction that contains a higher percentage of oil which will give you a high yield of fuel for the reaction. Some people use a lower amount of methanol in order to save money. The fuel may only be 85% biodiesel (the rest triglycerides, diglycerides and monoglycerides), but in many vehicles that level of conversion will never give any trouble.

How are you measuring the yield? Do you decant the resulting biodiesel and then measure it? You shouldn't attempt to make visual comparisons with the amount of glycerin that settles out as the glycerin contains most of the excess methanol. So if you use a higher percentage of methanol, that excess methanol will end up in the glycerin layer.

If you want to increase the conversion rate, then make sure you are using an adequate amount of catalyst, say 25% methanol, keeping the brew warm during processing and also continuing to keep it aggitated during the process. However, you may find that although your conversion has increased, your yield may decrease a bit.

Guys,
I have just posted some enquiries under methanol recovery that would have been better posted here because I am trying to find out how best to deal with the glycerine residue after reflux distillation to recover methanol. Please bear with me. Projects even remotely technical here in the Solomon Islands are a nightmare so I must have everything set up properly from the word go without any margin for error or review. Please help. I need a cheap and safe treatment for the post methanol residue (glycerine, and NaOH). But!!! Nobody has mentioned water although geewizztoo is adding it (I think) as a glycerine prewash. I will be using 600 ltr batches of low FFA pure filtered dried coconut oil with 120 ltrs Methanol and 2.1 kg NaOH. Theoretical residue 48 ltrs glycerine and 72 ltrs methanol/NaOH. I understand that some water will also be produced that will mix with the glycerine and methanol/NaoH. So will any prewash water. My dilemma is the easiest way to deal with this mixture. My gut reaction is to neutralise the NaOH with HCL because this would be cheap and environmentally acceptable. I understand that there is a good market for glycerine but I am not sure how to separate the brine solution from it. Any ideas please? I don't think KOH and H3PO4 is attractive here because of the higher cost of these reagents and the phosphate salt has no value in the Solomon Is. Has any biodiesel guru out there done any research on this? I would welcome your advice.
Best regards
Vernon Smith

Guys,
I have to make batches of biodiesel from 600ltr pure filtered dried coconut oil with 120 ltrs methanol and 2.1 kg NaOH. Theoretically I should get 48 ltrs glycrine and 72 ltrs Methanol/NaOH residue but some water will be present in the solution. Nobody has mentioned water although geewizztoo says he uses it (I think) as a glycerine prewash. My dilemma is what to do with the glycerine/NaOH residue after reflux distillation to recover the methanol. Using KOH and H3PO4 is too expensive here in the Solomon Is. My gut feeling says neutralise the NaOH with HCl - cheap and environmentally acceptable - but I am unsure how I would remove the brine from the glycerine so the latter can be sold. Has anyone done any work on this? I would welcome any guidance. Perhaps there are better ways of removing the water and NaOH from the glycerine. Please let me know you gurus.
Regards,
ffice:smarttags" />lace w:st="on">Vernonlace> Smith

Vernon,
I feel that your NaOH amount is too low. The currently agreed amount of NaOH for catalysis of the reaction is 5.0 g/l. To this must be added the titration amount of NaOH.

Has the CNO been titrated?
What was the titration amount of NaOH?
Remember that even freshly pressed oils can have high FFA%.

Your problems of use/disposal of the byproduct lead me to suggest that you read the paper "Glycerol as a by-product of biodiesel production in Diets for ruminants". Enter that phrase into Google to locate the paper. You may be able to use the copra meal and the glycerol to feed animals, creating a new industry and disposing of your byproduct.

Tony,
Thanks for that information. I already use all the spent copra meal for feeding pigs but there are no ruminants here. I will have to check on suitability of glycerine in pig feed. Thanks for the Google lead. Pigs usually digest anything that ruminants can but I will check. Lab equipment has not arrived yet to I can't titrate until it does. Various FFA levels in CNO is acknowledged, thanks for that tip too. Assuming I can feed the glycerine to pigs how do you suggest I get rid of the NaCl I propose making from the NaOH? Your input would be greatfully received. If all else fails perhaps it can go into the pig feed too but I will have to cdheck on that. My pig feed here is 47% spent copra 45% millrun from a local mill and 8% fishmeal from a local cannery. Gives very good results. My piggery is an important part of the project.
I will also look at an increase in the catalyst percentage.
Thanks and regards,
Vernon

Vernon,
NaCl will be present in the byproduct if you neutralise the NaOH in the byproduct with HCl. If you are using 5 g/l of NaOH and your byproduct is 15% of the oil volume, then you will have a NaOH concentration in the byproduct of 5g/litre /0.15 = 33 g/l of NaOH on the byproduct.
I am not up with the chemical niceties, but from a quick check of the Periodic Table, it would seem that Na is 11, O is 16, Cl is 17 and H is 1, thus NaOH MW is 28 (11+16+1) and NaCl is also 28 (11+17), therefore I believe that you would have a total of 33 g/l of salt in the byproduct. If the byproduct was mixed with solids (grain, coconut press cake) then this percentage would be an even smaller percentage of the feed.

Just a thought - so, do you need to remove the NaOH?

Hi Tony,
I agree with your calculations based on the MW of NaCl produced, in the region of 33g/ltr glycerine. Simply, no, there is no need to remove it. The recommended amount to add to stock feed is 10% of the dry feed weight so we will end up with 3.3g per kg feed. Insignificant I would say.
I have contacted the university of Keil for advise on feeding to pigs but haven't received a reply yet. I still don't know what to do with the FFA though. Any ideas? Looking at geewizztoo's photos from the JTF website FFA would be easy to decant if the glycerine and salt settles down beneath it. I am not sure if the same result would occur with NaOH/HCl as KOH/H3PO4. Has anyone tried? Please let me know.
Thanks for all your help,
Vernon

Hi Vernon,
If you are using hi FFA oil (used oil etc) then you will need to do a two stage acid base conversion.

Apart from that if your using good quality stuff like urr coconut oil then perform regular titrations to find out the percentage of it and make sure it dosn't get to high.

So basically if you get a good crop ie no infestations, good weather, your FFA level will be low and if your handling (processing) of your oil and biodiesel is good it will stay low and remain within the limits of good quality biodiesel.

I don't know what FFA percentage level will exceed the copper strip corrosion test but it would also be a combination of other factors aswell which you seem to be dealing with so make sure your FFA stays below 5%.