Has anybody had any success reacting the FFA/oil byproduct after removal of glycerol. It's probably around 80% FFA.

I think an H2SO4 process might work, but I've got no more acid to run some tests with.

Dave, could you please tell us why we would want to do this? And how we would be able to remove the glycerol? Just curious.

My apologies, Dave, for jumping in, but I've been working on this for the last month.

The benefits of converting FFA to fuel are twofold; first, of course is the benefit of being able to convert a good portion of the byproduct into usable fuel. There may not be much to be gained from each small batch, but if one has accumulated fifty gallons or so, as I and I'm sure others have, converting approximately half that into usable fuel is nothing to be sneezed at. Second, it should be a good first step toward reducing contaminants of the crude glycerin.

For those only able to get used oil with high FFA content, the benefits should be obvious. If a single-step base reaction is used, much of the oil will not be converted in the first step. Low yeilds result. Better yield is possible by using first an acid, then a base reaction. But this can be touchy, as discussed in other threads.

The soaps and FFA in the byproduct can be converted to usable fuel. I don't think there is any need to separate the glycerin from them first. In fact, this may be the simplest way to separate the soaps and FFA from the glycerin. I've posted the citation to an article in the Journal of the American Oil Chemists' Society several times on the board, but I'll post it again: Paper no. J9282 in JOACS 77, 373-379 (April 2000). The process is fairly water-tolerant, can be done at room temperature, and can have high yield percentages. It uses a large excess of methanol, so methanol recovery will be necessary. But otherwise, little new equipment or chemistry would be needed.

Dave, the Irish have done it and described their proceedure online in general terms. It's only a paragraph or two in a much longer article, but read carefully. Very encouraging.
http://www.teagasc.ie/research/reports/crops/4321/eopr-4321.htm

V-P

I've tried the acid alkali process as described by Alecs Kak on www.journeytoforever.org. It worked OK with less waste than with a simple base reaction. However, my miles per gallon were down by a good 10% compared to base reacted ester.

More interestingly, a 50/50 mix of base reacted ester and acid-base reacted ester brought my mpg back to normal.

I would really like separate the FFA-sourced ester from the oil-sourced ester. Then a proper fuel comparison can be done.

I've recently found out that leaving the acid too long is bad. It starts to work on the tryglyceride oil and doesn't do a good job making mono and diglycerides. They were probably what messed up my "foolproof" processed oil.

The naOH can be neutralised. Glycerine and salts can be washed out. The byproduct fats could then be reacted with acid. However we really need a way to separate the FFA so that acid is only used on 100% FFA. The byproduct always contains some oil along with the FFA.

Dave,

The easiest way to separate FFAs from triglycerides is to bind them up as soap in a straight base reaction, then extract them from the glycerin/alcohol/soap layer that settles out using 85% concentrated phosphoric acid.

You will get a precipitate of three variations of potassium phosphate on the bottom, a glycerin layer laden with alcohol and a FFA layer on top with minimal alcohol.

Continually salvage the pure FFA layer until you have sufficient volume for experimentation.

Industrial processes generally implement ~100 psi for esterification reactions. So don't count on turning 100% FFA feedstock into biodiesel with but a ml or two of concentrated sulfuric in a 30 gallon whirl bath.

100 psi is not a great deal of pressure, so it's not implausible that even shade tree biodieselers could prepare a small stainless reactor that would do GE's nuclear division proud.

Todd Swearingen

Yo -- haven't been over here in awhile; how you
all doing? Todd's got the right idea, I think --
get your FFA's out of the soap and you can get
a pretty clean layer of "pure" FFA. Smells like
s**t, and it's almost BLACK, probly carcinogenic,
whatever.... I've played around with trying to
make biodiesel from this, using conc. H2SO4.
The problem seems to be there's no easy way to
separate the mess after reacting. In the usual
TRANSesterification, the glycerine falling out
helps a lot -- it pulls the equilib rium, as well
as taking the water and most of the alcohol into
a separate phase. In an acid-catalyzed reaction
using FFA instead of triglyceride, there's no
glycerine to help with separation, the equilibrium
is very half-assed (maybe only 70-80% conversio n),
and the alcohol and FFA's are both fully soluble
in the biodiesel.

There's water in there, too, so anything you do to
remove the alcohol (like distilling it out) will
drive the equilibrium backwards!

I never solved it -- maybe Neutral has some
su ggestions as to how to actually get product
OUT of there after the reaction..... -K

After distilling most of the methanol, I tried separating the gunk with acid and water.

With KOH and H2SO4 got a water/glycerol layer with fats above and a salt layer between. I guess NaOH and HCl would result in common salt dissolved with the glycerol.

The fats can be used as engine fuel, but they have to be designed to run with thick fuel oils.

I have no idea if the supposed corrosive effects of FFA is actually borne out when it's used in these engines.

Provo - Could the whole mess be acid esterified glycerol, fats, methanol and all. Or won't the reaction equilibrium support that. I'm still a bit puzzled on that point.

Dave

Esterification of pure FFAs is generally conducted under high(er) pressure and temperature. Otherwise the conversion rate is next to zip.

The same holds true for esterification of recovered FFAs from biodiesel and even esterification of extremely high FFA content WVO.

100 psi rated tanks are not at all uncommon.