The FFA recovery equation requires excess acid to achieve the glycerol separation. The overwhelming majority of the excess should reside in the recovered glycerol/methanol layer. On the other hand, there's apt to be a microscopic, perhaps "negligible" amount of phosphoric acid in the recovered FFAs. A simple wash would put the kabosh on that.
Todd Swearingen Keith Addison wrote: >>Ken, >> >>Acid catalysis works well. Industry often uses feedstock of 100% FFAs in >>order to achieve a "pure" or nearly pure mono-ester product. >> >>The easiest way to test the theory on a pauper's budget is to take the >>glyc cocktail from two side-by-side trials from identical feedstock and >>reaction conditions, one a/b and one strictly base, and recover the >>FFAs. To reduce sample error, larger batches would help, at least a >>galon or thereabouts. >> >>Todd Swearingen >> >> > >A question about recovered FFAs from separating the glyc cocktail. I >want to do some tests using a/b with high-FFA oil, and I don't have a >lot of high-FFA oil. I'm looking for a cut-off point where I'll have >to change the method, and ideally I'd like a range of oils with >increasing FFA content (up to about 25%), but I'm not going to get >that. What I'd really like to do is add FFA by increments to the same >low-FFA WVO. Could I use FFA separated from the glyc cocktail for >that? Does all the phosphoric acid and all the KOH end up in the >bottom layer after separation or will there still be some left in the >FFA to confuse the issue? If it's still there in the FFA, could it be >neutralised? Any ideas? > >Thanks much > >Best > >Keith > > > > > > >>Ken Provost wrote: >> >> >> >>>On Dec 30, 2005, at 11:34 AM, bob allen wrote: >>> >>> >>> >>> >>> >>>>acid/base method for conversion of wvo to FAMEs >>>>The following is my modification of that procedure >>>>which works for us, and takes less time, but requires >>>>more catalyst. >>>> >>>> >>>>Dissolve 1 ml sulfuric acid in 150 ml methanol and >>>>add to 1 liter liter dry wvo, heat to about 60 Celsius >>>>for one hour. Then dissolve 4.9gm NaOH in 50 ml >>>>methanol and add to the reaction mixture. Continue >>>>heating for an additional hour, stir for one more hour >>>>and then let set for 8 or more hours. Workup as usual. >>>> >>>> >>>> >>>> >>>> >>>Sounds right -- now as to the basic theory: Have you >>>been able to verify that the acid catalysis stage actually >>>accomplishes anything? In other words, starting from >>>some high FFA feedstock, do two experiments: >>> >>>1) Single stage with excess alkali as required to neut- >>>ralize the FFAs. This would be expected to produce >>>much soap and reduced biodiesel yield. >>> >>>2) Your method as described above, which should >>>theoretically reduce the soap formation dramatically >>>with proportionally higher biodiesel yield. >>> >>> >>>I did my best to verify this a few years back, and found >>>the acid actually didn't help much. Just curious.... >>> >>>-K >>> >>> > > >_______________________________________________ >Biofuel mailing list >Biofuel@sustainablelists.org >http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org > >Biofuel at Journey to Forever: >http://journeytoforever.org/biofuel.html > >Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): >http://www.mail-archive.com/biofuel@sustainablelists.org/ > > > > > _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
