The holy grail of ethyl esters- using waste oil.

I know it can be done using some other methods (saponification of the bad oil and then breaking up the soap and esterifying the fatty acids that result).

Has anyone done anything with the regular ol' esterification/transesterification process that we know and love?

Hello again, everyone -- been busy for a few years building my off-grid strawbale house. My, you all have been doing some great work since 2003

I just did my first ever acid-base on some oil that titrated at 7.5 ml. This time I used methanol both steps, but I'm thinking it would be very easy to use ethanol (even with some water?) for the acid stage, and methanol for the base step.

The advantage is all the methanol in there would guarantee a good glycerine separation in the base stage. Also, I think the tendency of the ethanol to go into solution in the oil might give a quicker esterification. Anybody tried this?

I'll report back when I have results.

Gonna try a couple of ethyl esters acid base batches this weekend, and I'll let you all know the results.

No luck so far with acid-base process using ethanol. Here's some results:

300 ml WVO, titrates 7.6 with NaOH
50 ml anhydrous denatured ethanol (2% gasoline)
0.5 ml 96% H2SO4 (1.7 ml per liter oil)

Add acid to ethanol, mix with oil, heat to 54C in sealed pressure vessel,
constant heat and periodic agitation (every 1/2 hour or so) for 6 hours,
let cool overnight. One cloudy phase titrating at 4.0 Na, of which approx 2.5 is due to the H2SO4.
Make alkoxide with:

85 ml ethanol (same stuff)
15 ml methanol
4.5 g KOH (9.4g + titr. per liter oil)

Add to WVO phase, heat to 50C, agitate for 3 hours, no separation. At this point, mixture is VERY sudsy, like there's a lot of soap.

Forced a separation with 50 ml of old glycerine phase from a 10% prewashed
methanol batch. Separation started almost immediately, but ended up with
255 ml of a "glycerine" phase, and 175 ml of "biodiesel" phase.

The biodiesel phase was LOADED with soap and/or mono- and diglycerides, and formed an emulsion immediately when I tried to bulk wash it with hot water.

Seems clear that conversion was poor and way too much soap was formed. WVO was dry enough to make fine methyl esters, methanol was 99%, and ethanol was 99+% with the hydrometer. I'm thinking maybe the water formed during acid esterification, plus the water formed during the alkoxide reaction, plus the water formed neutralizing the H2SO4 and remaining FFA, was all just too much for an ethanol-based reaction.

I'll keep hammering at it....

Sorry -- typo in the recipe. Alkoxide mix used 35 ml ethanol , not 85 ml.

-Ken

Found an interesting pdf -- they made biodiesel using an acid-base process much like FATTA, in which mixtures of ethanol and methanol were used to get better results than straight ethanol:

U Saskatchewan 2006 Biodiesel Paper