Hi all.
I'm in the first stages of processing and ran into a titration problem. I
don't seem to be able to get the wvo to mix properly with the rubbing
alcohol. I've stirred vigorously but just end up with little beads of oil
in the alcohol, any ideas?.
Warm it up. Stand the beaker or whatever in a bowl of hot water.
Generally, titrate at the same temperature you process at, about 55
deg C, 131 deg F. Are you using 99%+ isopropanol? 70% is said to
work, but I tried it and didn't think it worked as well as 99%+. The
WVO will not dissolve as easily in 70% as in 99%+.
If your WVO has a lot of Free Fatty Acids (FFA) you'll have to add
quite a lot of 0.01% NaOH solution for it to reach the desired pH of
8.5; it's mostly water, and the more you add the less inclined the
WVO will be to stay dissolved in the alcohol. So stir! It doesn't
make too much difference if it comes out of solution, you can still
get an accurate pH reading.
Most of the info I've read suggest that the correct amt of Na0H is between 6
and 6.25g per litre, and 15 to 20% methanol.
That information is wrong. The correct amount is the amount indicated
by titration plus the basic amount of 3.5 gm/litre v/v oil.
http://journeytoforever.org/biodiesel_make2.html#lyeamount
How much lye to use?
15% methanol is too little: some oils need that or more for the
stoichiometric amount, and excess is needed to push the reaction
towards completion. See:
http://journeytoforever.org/biodiesel_meth.html
How much methanol?
I went ahead and blended three 1 litre batches with differing methanol and
Na0H contents and here's what I got.
#1......1 L.wvo 6.2g Na0H 15%methanol== Light honey colored after
settlement, glycerine looked clear colored and like wax in the bottom of the
jar.
#2......1 L.wvo 6 g Na0H 15% methanol...... looked the same as the mix of
6.2g Na0H
#3......1 L.wvo 6g Na0H 20% methanol.... light honey colored but appeared
to be more glycerine and the glycerine was a darker almost brown color.
Is there anything to be learned from the amount or color of the glycerine
after the reaction?
Not directly, and not really at that stage.
I tried the wash test mixing equal parts H20 and finished product,on all
three, but none of them separated cleanly.
That's here:
http://journeytoforever.org/biodiesel_vehicle.html#quality
Take another sample from each of the test batches and do the next
test, below the first one, which starts like this:
"Todd Swearingen of Appal Energy in the US offers some useful D-I-Y
tests: "The barnyard tests for your fuel are to take a liter of
finished fuel, process it again as if it were virgin veg oil. If any
more glycerine drops out, then you know it wasn't as good as it could
have been..."
Virgin veg oil
http://journeytoforever.org/biodiesel_make.html#biodnew
Start again, at the beginning.
"Where do I start?"
http://journeytoforever.org/biodiesel_make.html#start
Then focus on getting the titration right so your test batches pass
the two quality tests above. Be meticulous about it. Check that your
scales are accurate as well as your measuring flasks, syringes or
pipettes, that you're using high-grade lye, it's fresh, you've kept
it dry, that whatever you're using to measure pH is up to the job: a
good pH meter that can be calibrated (and is, regularly), or fresh
phenolphthalein solution (keep it in the dark) - but NOT phenol red.
When you check out Luc's processor page have a look at what he says
about test batches. Read everything at this page about titration,
lye, etc:
http://journeytoforever.org/biodiesel_make2.html
Best wishes
Keith
Scratchin' my head on this one.
Buck
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