Natural Science Forum / Chemistry / Organic Synthesis / November 2005

Take the wet algal sludge and heat it in a closed pressure container
above 350C. Hydrothermal conditions are best for what you are trying to
do.

It would be really nice if someone could find a mutant strain of algae
which pushes the oil out ttrough its cell wall instead of storing it. The
oil could just be skimmed off the top of the water.
Of course the mutant would have to be dependant on some nutrient or factor
which isn't found in the wild, otherwise oil slicks could develop if it
escapes.

What about steam distillation?  I just set up a steam still to extract
oils from plant materials.  I don't see that is matters whether the
plants are one celled, small colonies or angiosperms.  If you
concentrate them as muha suggests in the word sludge, you can then
handle them as you choos from several methods.  I

I'd consider steam or vacuum-steam rather than having to mes with a
lot of expensive solvents.  Another technique, more expensive but fast
and effective is critical butane extraction.  Build a chamber that is
long    and narrow and able to hold some pressure.  provide a standard
gas inlet at the top and a cock at the bottom or perforations at the
bottom.  Fill it with dried algae sludge and fill it with liquid
butane.  The butane will come out the other end carrying all the
solvated compounds nd then release tham by evaporating off.  You might
run it through a fractionating column at the end to reduce any
co-distillants.  I'm typing while I think so bear with me .  You could
set the butane extraction so that the mix of critical butane and
hydrcarbons is released to a refluxing column of methanol or hexane to
capture volatiles and azeotropes.  I can sketch this.

I like the butane idea but will the process rupture the cell walls? is
that even necessary?  The steam concept sounds good and very strait
forward but the energy cost could be higher. how could a comparison be
made?