Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: beheada on May 15, 2006, 07:01:04 PM
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I'm currently working on making some biodiesel just to see how difficult it is, and also trying to figure out the cost effectiveness of making it at home in comparison to the cost of diesel fuel right now. Well, I used Red Devil Drain Cleaner (NaOH) and ACS Grade Methanol with the Kroger brand Vegetable oil (made from soybean oil). My final product after mixing the methoxide and adding it to the oil, then shaking vigorously, was light yellow colored, as opposed to a chocolate milk color that was supposed to be present after mixed. I've followed the directions to a "T", but for some reason there seems to be a difference. Perhaps it's the soybean oil?
I even blow-dried the mixing container I was using to avoid any type of hydration of the product.
The glycerin and biodiesel have separated, but the glycerin layer is clear and the biodiesel layer a misty yellow. I was under the impression the biodiesel should be a clear yellow and the glycerin a dark brown.
Where else could I have gone wrong in the process?
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Pure glycerin is clear, so that part of it should be right. I'm not sure about the rest of it. Maybe impurities from the drain cleaner or vegetable oil? Just trying to through out some possibilities.
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I have done this a few times. Did you wash the biodiesel? When I have performed this experiment I almost always end with a cloudy product just before washing.
Joe
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I washed 1 liter of biodiesel with 500ml of dH2O 5 times, and each time it got progressively clearer and less cloudy. I guess I jumped the gun on whether or not the product was correct, because I hadn't done the washes yet. The biodiesel I wound up with after sitting all night wound up looking like the pictures you see everywhere of biodiesel. The glycerin I wound up with is DEFINITELY not clear, but kind of a light brown color which settled on the bottom of the biodiesel layer because I removed it.
Is there anything constructive you can do with the extra glycerin? Any way to "clean it" and make it clear? There's alot of soap articles when you look up supplies for biodiesel, so I'm assuming it has something to do with making soap?
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A well done transesterification under nitrogen will have absolutely no color (perhaps a light yellow). Color is typically an empirical observation based upon higher temperatures and oxygen introduction that introduce impurities that partition into one phase or the other. It sounds like you're there. Wash it well to get rid of residual base and to remove the glycerine.
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This website may give you some ideas about what to do with the glycerin.
http://en.wikipedia.org/wiki/Glycerin#Applications
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I have never tried to purify the glycerin but that might make for some fun experiments.
Joe