Everyone,

Note that I've been making BD for a couple of years, but yesterday did my first experiment with acid esterification on a 1 liter sample.

My question has to do with what I found this morning. My 1 liter sample was about 80% 'creamy snowflakes' and 20% oil. What are these snowflakes?

OK my process. I know it wasn't perfect, but I thought I'd ask some experts to catch all of my mistakes before repeating.

Started with 1 liter of BBQ grease drippings. Very thick at room temperatures, but not quite solid. I heated & filtered through a paper towel. Yes, my first possible mistake was not testing for water.

Titrated it twice, titrates around 10 (NaOH, not including base). One question here, when I titrate dissolving in isopropyl alcohol, it looks like there is some fat that floats (creamy colored) that I can't get to dissolve. If I heat it, it'll melt, but still won't dissolve. So is that fat? But being that it won't disolve, I may be titrating too low.

Heated in microwave to 130F and added 10% methanol and 2 ml of sulfuric acid. I don't know the concentration, this is from Lowe's the FlowEasy Drain Cleaner. It calls itself 'virgin sulfuric acid'. Yes, possible mistake #2, unknown chemical concentation. But has anyone ever heard of 'virgin sulfuric acid'? In my search, all I found was 93 & 98% pure when that term was used.

OK, continuing. Oh, note that I added the acid first, mixed gently, then added the methanol. I should have double checked the mixing sequence, does that matter?

So I put this in a sealed container with a magnetic mixer inside & put it on my mixer. Ran it about 5 hours, with maybe 3 times putting it into the microwave to reheat. Then let it settle overnight (at 70F). When I heated it, it did want to off-gas a little (methanol evaporating?). Was that a problem?

This morning it titrates closer to 7. That's good news. But what worries me is all the solid precipitation.

My guesses/thoughts. 1) Definitely need to boil off water before starting. 2) Need to hold to temperature more steady & possibly much longer. 3) May need to increase acid % to compensate for all the undissolved fat.

But my biggest concern is all the precipitates. Any suggestions?

Gotta go. Much more dangerous than sulfuric acid: teaching 6th grade Sunday School!

-tony

try warming you sample back up. please do this carefully there is methanol in the mix. you might try a hot water bath outside.
you're most likely looking at high melting fat. the acid process won't help break down the high melting point fats. it just convert them to high melting point biodiesel.

yes. making sure the oil is dry to start with helps.

-dkenny

When shopping for concentrated Sulfuric Acid ask for an MSDS(Material Safety Data Sheet) this will tell you the concentration.