Hello All,
Some time back Chris Tan presented an interesting idea: Use the glycerin
mix from BD processing to lower FFAs and decrease water in WVO.
I've begun testing the idea. Results are preliminary at best, but I have a
few observations that I'd appreciate comment on.
Process: I titrated and then loaded 90 L WVO along with 9 L glycerin mix into
the processor. The mix was pump agitated and warmed to about 75 F (25 C). I
left the pump on for about 45 minutes. As soon as I stopped the pump i removed
a sample of the mix so I could see when it had settled. I also titrated this
daily to see when the titration stabilized (2 - 3 days).
I let the mix settle for 5 days and then drained the glycerin from the
bottom. I then removed and titrated a sample of the WVO. I prepped appropriate
methoxide (20% vol/vol), and processed the oil based on the second titration
(treated WVO).
Results: - Original WVO titrated 2.7 (I use 0.1% KOH titration solution; made
from 90% KOH)
- Treated WVO titrated 1.8
(Same for oil from the reactor and from the sample removed
earlier)
- BD passed Warnvist Quality Test.
Observations:
- I noticed a distinct creamy layer between the settled WVO (top) and the
glycerine (bottom). I presume that this is tallow as it clarified upon heating
and clouded up again upon cooling. I hadn't noticed any tallow in the WVO I
loaded into the processor.
- I did not notice any difference in the amount of soap produced in the wash
test. (Less water and FFAs in the WVO should result in less soap.) This is
probably because I used good oil (2.7 using my KOH titration solution is the
equivalent of about 1.7 using .1% NaOH).
- I did notice some things different about the glycerin after "treatment".
a. It was less offensive in terms of odor. (Less methanol?)
b. Although by no means was it clear, it did appear less opaque ..... swirled
within a clear glass jar it appeared "cleaner" than the untreated glycerine.
c. I was unable to determine whether or not pH was significantly affected, but
the "treated" glycerin produced noticeably better, and more persistent bubbles
when shaken with water than the untreated glyc. I was able to approximate the
effect by adding a very small amount (a few drops) of phosphoric acid (not
enough to crack the mix) to untreated glycerine.
Comments and Questions:
I use the "primitive", but effective single stage base method for making
BD.
The WVO I typically get is of very good quality. If the oil I get titrated
above 3.5 or 4 (using KOH), I would probably go to the 2 stage acid/base
process.
This idea of treating WVO with the caustic glycerine co-product interests
me because it may make the glycerine more "compostable".
A couple of years ago I used glycerin (pH = ~5.5) split from the mix, on
my compost piles and found that it not only composted well, it seemed to
increase temp and the rate of decomposition.
I've been composting unsplit glycerine (pH = ~ 9) without problem, but am
concerned about the pH of the glyc cocktail. I also have the impression (only
the impression) that soaps in unsplit glyc. resist breakdown.
The split glycerine dissolved well in water and did not clog my sprayer.
The unsplit formed a goo (insoluble soaps??) that did clog the sprayer.
Treating the WVO with glycerine might also be viewed as treating the
glycerine with FFAs. If the glycerine contains less water-insoluble soaps, and
is of lower pH, the process might be doubly beneficial i.e. lowering water and
FFAs in WVO and improving the composting properties of the glycerine cocktail.
Questions: (Take your pick)
- FFAs are very weak acids. Is this why the WVO titration did not drop to
zero?
Would longer treatment or more glyc. cocktail be needed to further lower FFAs?
- A while back it was suggested that I add a small amount of phosphoric acid
to my first wash to help remove water insoluble soaps. Does decreasing pH
increase the solubility of otherwise water insoluble soaps?
- I didn't notice tallow in the WVO I loaded into the processor, but it was
clearly evident in the settled mix after treatment; same temp as the original
WVO was. Any explanation? (Could be I just didn't see it)
- The odor of the glycerine was distinctly less offensive after treatment. I
suspect there was less methanol present. The temp of the mix never even reached
80F (27C). I can't imagine that it was used to form methyl esters. Is the
presumed "missing" methanol now dissolved in the WVO (90 L WVO vs 9 L of
glycerine).
Any other reason for the change in odor?
My this has become quite wordy. Sorry 'bout that
Tom
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