New to posting, I have recently tried a raw glycerin prewash for my crappy oil I collected this week. Hot in the past month here in LI NY.
The oil in the 250 gal container from where it came from had that smelly formented odor. Heated it, settled & dewatered it and filtered it as usuall still with that odor. Titrated at 4.5. The highest I ever had. Passed the hot pan test for moisture and still smelled. Heated 200 gallons of this oil to 120 degrees added 40 gallons raw glycerin and mixed for 45 minutes. Using NaOH as my usual catalyst, I drained the next morning and it was very thick but pourable. Yielded 5 -8 gallons less of gycerin. Heated oil back to 130 and now titrated at 4.0. Was'nt too happy!! The oil did have that methoxide odor to it but still treated it as normal 20% methanol and 6000 grams of NaOH. Seems that some hardened glycerin was on the side walls of my processor and saw it spinning in the early stages of my process. The pump and heat liquified it. The end result was no better at all. Drain out 50 gallons of glycerin. What did I do wrong, if anything??

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Originally posted by Andrew Morris:

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methanol definitely gets mixed into the oil with glycerine pretreatment.

Right. The question would be how much stays in the oil given the limited solubilities of oil and methanol? And, is that enough to have a significant effect on conversion - ie can we use less methanol and still reach the the same level of conversion?

I am a biodiesel newbie, and chemistry was a sore spot in college. With that said, i will share my observations. I have regularly been pre-treating with no less than 20% glycerin. It only costs me time and saves on KOH by lowered titration. My last batch was run with 18% methanol instead of the ususal 20% and it passed the 3/27 with flying colors. When I demeth and settle for 24-48 hours, soap is minimal. I believe that some methanol is cooked out during the mixing process, so I apply about 10 lbs of pressure to my settling tank to reduce this. I say this because I vacum my methoxide and oil through a reaction chamber into the settling tank and I always find some methanol in the air compressor tank.

One other person has indicated to me that they pre-treat and they are using 16% methanol regularly. I plan to work my way down to that percentage.

And finally, I drywash with Magnesol, but I have found that after de-mething and settling I have fuel that is almost as clear as the drywashed fuel.

I just treated 50 gallons of dry WVO with 12-13 gallons of glycerine from my 50gallons I have stored. I mixed with heat for 2 hours and settled over night about 10hours.

I then drained exactly 10 gallons of glycerine, it was thicker still able to pour, but did not smell like methonol at all!

I now have 52-53 gallons in the reactor, i'm proceeding with my acid stage using 250ml of acid and 4 gallons of meth

Inital titration - 16
After glycerine treatment - 8.5 ( happy !!! )


I'll post to let you know how I did after the acid stage

Dear Lauf
Why didn't you treat again with glycerol so you don't have to do acid treatment? It's a hell of a lot easier and safer.

Well I have a biopro so it's setup using the acid step then base. I dont understand why so many people say it's not safe? I pump out of my barrel into measureing cup and pour into reactor? easy process! wear gloves and glasses duh!


Okay anyway after I did it I ended up with a layer of white/yellow glop, kinda seemed like water? Hard to say.... My titration did not change