Hello Filip I've done quite a lot of work with this, though not as much as Todd, but it was with phosphoric acid, not sulphuric acid - I don't know if Todd's used sulphuric, but I think not. I do know that acidifying soapstock is usually done with sulphuric acid, so, since this is very similar, I don't see why it shouldn't work. But I haven't tried it (and I don't know from molecular weights - unlike Ken!), so I can't help you with the amounts you've used.
However, since you're having trouble with sulphuric, I suggest you change to phosphoric acid and see if you still have trouble. If so maybe we'll be able to help you, or at least discover something worthwhile, with one less variable to deal with. I think, for a start, tell us a bit more about your biodiesel process - you used 5g NaOH, but did you titrate the oil? What was the titration? How much methanol did you use? How long did you agitate it and at what temperature? Did you dewater the oil first? If so, by boiling it off, or by heating and settling? >Hello, > >I'm new in making Biodiesel, and while trying, I came up to something I do not >understand. >From one of the one-liter batches I'm trying, I tried to split the soap again >into FFA. >So the deposits of the trans-esterification, I seperated, and mixed with >H2SO4. > >The oil source was WVO, animal fat based. (French fries) For the BD proces, I >used 5g NaOH. >Now in advance I calculated I would need 3,5 ml of my 95% h2so4 to get the >mixture to ph7. >(Am I right?) > >I now already added 10ml of H2SO4, and still no sign of seperating glycerine. >Who can help me in this? >Is the H2SO4 reacting with anything else but NaOH and soap? > >Thanks >Filip >follow-up on my question, see answers below >Who can help me on this??? > > >> > >>From one of the one-liter batches I'm trying, I tried to split the > >>soap again into FFA. So the deposits of the trans-esterification, > >>I seperated, and mixed with H2SO4. > > > > > >both phases, or just the glycerine phase that had already settled out > >using an NaOH catalyst? It's not clear (to me at least) if you have > >even produced biodiesel here. If you already have a biodiesel phase > >and a glycerine phase, obviously separated, subsequent extraction > >of FFA should involve acidifying ONLY the glycerine phase. > >I first separated de Biodiesel from the deposits (glycerine+soap+NaOH+...) >Only the lower phase was used to add acid. > > >>The oil source was WVO, animal fat based. (French fries) For the > >>BD proces, I used 5g NaOH. Now in advance I calculated I would need > >>3,5 ml of my 95% h2so4 to get the mixture to ph7. I now already > >>added 10ml of H2SO4, and still no sign of seperating glycerine. > > > > > >Here's where I get confused. If you've successfully made biodiesel, > >you should have already seen glycerine separation after the NaOH > >step. Perhaps you're confusing the separation of glycerine with the > >separation of FFA, which requires acid rather than base. > >From step one, the trans-esterification process, I separated the esters from >the lower phase. >The lower phase, once acid is added, should separate into salt, glycerine and >FFA. This separation does not occur! >I keep on having a blackisch glop, and the more I add acid, the more it >stinks...but not different phases (salt-glyc-FFA), already added 25ml H2SO4 > >This is in the case I use animal fat based WVO from the french fries shop >around the corner. I also did the same with WVO (vegetable based) from a >different source, >I get about the same amount of Biodiesel, and from the lower phase, after >adding acid, I get a more or less clean split of the glyc. and FFA, but not >noticable salt layer. I would expect Na2SO4. I'm going to try to dry the glyc. >layer, to see if the Na2SO4 is still dissolved in the water in the glycerine. > > >If, on the other hand, it's I that is confused (often the case :-)), and > >you are acidifying just the glycerine phase, after separating it from > >a successful biodiesel reaction, then I would agree with Mark -- keep > >adding acid. The FFA will eventually float up to the top as a dark > >reddish-brown, odd-smelling oily layer. > >I already added 25ml H2SO4! It is smelling very badly and giving fumes... > >Filip >It sometimes takes time for you to see the results (24 hours?) . I don't >know enough aobut this to know if the calculation is correct, however you >can do a trial and error test series to figure out how much acid to use. >The first time I did this, I did a small test batch and with no results >after a couple of hours it seemed to be a failure and I set it aside and >forgot about it. the next time I picked up the jar a few weeks later, I had >to do a serious doubletake- it looked like biodiesel in reverse with the >dark stuff (looking for all the world like glycerine) floating on top. It >took a minute to realize it was the ffa recovery test jar! >Mark Todd was making this point earlier Mark, re using less acid - once you find out how much is needed for a fairly quick split, then cut back on the acid. I also found if you left it longer you could use less, but I haven't yet got as far as figuring out what the limits are. It's worth doing I think, phosphoric acid is expensive. Best Keith Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
