Kavitha, You will have no visibly discernable biodiesel after conducting the acid side of an acid/base catlysis. The ethyl or methyl esters will remain homogenously mixed with the glycerides. Acid catalysis in this particular reaction, although the best method for converting free fatty acids to esters, is an extremely slow reaction in comparison to base catalysis with glycerides. Thus the call for both acid and base stages - the best of both worlds and a higher total yield.
Once you complete the acid side of the process you need to continue with the base side. Only then will you have the ethyl ester that you are looking for. Both NaOH and KOH will dissolve in ethanol, although not as quickly as you might wish. You'll have to develop a method that meets your time constraints - that, or change your time constraints. Todd Swearingen ----- Original Message ----- From: kavitha palaniappan <[EMAIL PROTECTED]> To: <biofuel@yahoogroups.com> Sent: Sunday, February 02, 2003 2:35 AM Subject: RE: [biofuel] Biodiesel using acid catalyst > > Hi Filip, > You are absolutely right! I am going through the learning curve and I used 30% ethanol to oil ratio. At the very beginning, I had tried with methanol and base catalyst (NaOH) and I also succeeded in getting good quality biodiesel. But, during my first review at college, my prof. said that I should try with ethanol as methanol is carcinogenic. So, I tried ethanol with base catalyst. Unfortunately, NaOH was not sufficiently soluble in ethanol and the process resulted only in soap formation (the whole mass solidified). This, I tried with different ratios of ethanol to oil and the result was the same. So, I switched over to acid catalyst. Moreover, I was considerably encouraged by some chemistry books which said that acid catalysts work faster than base catalysts. > So, now, do you mean to say that whatever I suspected as biodiesel with ethanol+acid catalyst is not biodiesel at all? Is it just a blend of ethanol with oil? Will I get into trouble if I use it in the engine? If yes, what sort of problems would I have to face? > How can I go about with acid-base catalysis as the base seems to be sparingly soluble in ethanol? Kindly help me! > Kavitha. > "filip.ponsaerts" <[EMAIL PROTECTED]> wrote: > Hi Kavitha, > > From your mail above, I suspect you are just going through the learning curve, > just as I did recently (and still are) > 1) Two layers, top with properties of ethanol, lower as biodiesel.... > I suspect you used +25% ethanol to oil ratio... You have most likely the > undisolved ethanol on top, with some components of the oil still dissolved, > hence the color. The oil layer will be saturated with some dissolved ethanol, > which gives the oil some properties like biodiesel (e.g. viscosity) > 2) Ethanol is much more difficult to work with. Take it from me, and I'm sure, > the rest of the people on this forum... start with methanol until you got this > up and running. > 3)If I understand correctly you are ONLY using acid. Acid transesterification > is VERY slow, and hard to get above 50-65% yield. Read in the chemistry > books... good for labs, but for industrial use, you would need +200 degrees > celsius and high pressure to get higher yield in reasonable time. > > Look for acid-base, or base only scenarios, certainly to start with. > > Regards, > Filip > > > > > 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 the Yahoo! Terms of Service. > > > > --------------------------------- > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now > > [Non-text portions of this message have been removed] > > > > 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/ > > > 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/
