May 02, 2009, 03:08 PMrl303
How Much Ethanol?
Has anybody tried centrifuging out the suspended glycerin proir to a drywash?
The reason for this is of course that ethanol is a great cosolvent that keeps glycerine droplets from settling, and soap along with them. I had no way to test the glycerine content but I'm pretty sure it'll be abnormally high.
I'm looking into going with ethanol instead of methanol because I was doing a little research and the VOC's released into the air with the methanol are huge compared to ethanol and could get expensive on commercial scale with the new 'Cap and Trades' coming down the pipeline. Besides, whats the point of making biodiesel with methanol if your going to become a gross polluter in the manufacturing process and harm the environment anyway?
April 27, 2011, 02:00 PMWesleyB
I got a quick, clear separation of ethyl biodiesel from glycerine layer by adding half a molar equivalent of concentrated sulfuric acid of the lye catalyst I used, to the reaction product of the transesterification reaction, with shaking the bottle it was in. After decanting the crude ethyl biodiesel, I purified it with magnesium silicate, heat and stirring. Prior to using magnesium silicate I removed most of the excess ethanol with vacuum distillation. Initially I used 99.5% anhydrous ethanol in the transesterification reaction. I don't have my notes with me right now.
June 07, 2011, 10:03 AMWesleyB
I reacted 200 mililiters new corn oil with 48 mililiters 99.5% ethanol that had 2.4 grams of lye in it, for about 2 hours at a temperature of 60-72 degrees C, in a hermetically sealed, one liter, single neck, round bottom boiling flask with magnetic stirring. I removed the teflon coated magnetic stirbar, replaced the stopper and let the reaction product sit about 24 hours. It separated nicely, forming two phases. I don't know what "the literature" says about the optimum amount of excess dry ethanol to use for a similar transesterification reaction, but this seems to be close to the correct amount to use for new, dry corn oil. The upper phase product is liquid at about 70 degrees farenheit. I haven't yet done a 27/3 test on it. After making ethyl biodiesel several times, it seems to me that the biggest factor in achieving a two phase separation is that the starting materials are dry (without water, almost anhydrous). I figured corn oil to average 876 grams per mole for the triglyceride, based on information in an old organic chemistry book. About 36.5 mililiters of anhydrous ethanol would be the 100% stociometric amount to use for new, dry corn oil. So I used about a 31% excess of dry ethanol for this reaction. It worked just fine.
June 08, 2011, 03:05 PMWesleyB
I maybe should clarify things in my last post. I figured the average corn oil triglyceride to be 876 grams per mole. So for new, dry corn oil 182.6 mililiters of dry ethanol would be the 100% stociometric amount to use per liter of new corn oil. I titrated (for the first time) new corn oil to be 0.66 grams of NaOH per liter to deal with the free fatty acids in the new corn oil. I did the titration in 95% grain alcohol using 5% phenolpthalein indicator solution, but at room temperature of about 75 degrees farenheit. I used about a 31% excess of commercial grade anhydrous ethanol, 199 proof, in the transesterification reaction.