Re: Fw: Bio diesel

[Keith Addison <keith@journeytoforever.org>]

>Hallo Keith,
>
>There  is  a fellow on the Energy Resources mailing list who is making
>biodiesel  (in the Netherlands) and he says the soap produced from the
>residue  is of poor quality although it cleans well and is looking for
>a  recipe  to make a decent glycerine soap.  Is there anywhere you can
>point me so I can send him the url?
>
>Thank you kindly friend.  Great pages!
>
>Happy Happy,
>
>Gustl

Hello Gustl

I'm glad you like our pages, thanks. Is that Pieter Koole? I saw his 
message on bioenergy@crest.org and was intending to post a response 
to bioenergy cc'd to him. So I'll reply to you and cc to both.

First, there's a lot of info on glycerine here:
http://journeytoforever.org/biodiesel_glycerin.html

The by-product of biodiesel manufacture - what sinks to the bottom - 
is glycerin plus saponified free fatty acids, free excess methanol, 
and lye (either NaOH or KOH). If the feedstock is used cooking oil, 
the amount of FFAs can be quite high.

That it burns the skin isn't too surprising. Generally the advice is 
to leave it exposed for about a month (as with soap) before using it. 
That would allow the lye to finish working on the glycerides, and 
allow excess methanol to evaporate. That leaves you with what's often 
called an "industrial-type" cleaner or degreaser. I don't think it 
can easily be made into a pleasant, quality soap.

Otherwise, the excess methanol can be recovered for reuse (best), or 
it can be evaporated off by heating the glycerin to 65 deg C or a bit 
more (boiling point of methanol 64.7 deg C). This needs good 
ventilation, the fumes are poisonous, and highly inflammable. 
Recovery is the same, but lead the escaping fumes through a simple 
condenser.

Adding phosphoric acid to the glycerin layer precipitates out the 
catalyst in the form of either potassium phosphate salts, which can 
be used as fertiliser, or sodium phosphate salts, less useful. It 
also converts the soaps back to free fatty acids, which float on top, 
and can be recycled back to the next batch for conversion to 
biodiesel. You're left with a light-colour precipitate on the bottom, 
glycerin/alcohol/water in the middle, and FFA/alcohol on top. Alcohol 
can be recovered (or evaporated) separately from each of the top two 
layers. The middle layer will be a purer form of glycerin (about 
95%), which can be sold (if not for much), or added to basic liquid 
soap to make a high-glycerin soap, very nice for the skin. 
(Commercial soap producers remove all the glycerin, which makes for 
harsh soap.)

Purifying the glycerin further than that so it can be sold for a 
decent price is very energy-intensive, not worth it unless you're 
already set up for that and can justify the energy use.

I hope this helps.

Best wishes

Keith Addison
Journey to Forever
Handmade Projects
Osaka, Japan
http://journeytoforever.org/

 


-
Bioenergy List Archives:
http://www.crest.org/discussion/bioenergy/200202/

Bioenergy List Moderator:
Tom Miles,  tmiles@trmiles.com
List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

Sponsor the Bioenergy List: http://www.crest.org/discuss3.html
-
Other Bioenergy Events and Information:
http://www.bioenergy2002.org
http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
http://www.crest.org/articles/static/1/1011975339_7.html Gasification
http://www.crest.org/articles/static/1/1011975672_7.html Carbon