Friday, April 25, 2008

Home Biodiesel Production Part 2: Titration

I think I'm getting a little better at this video production thing. Unlike the video about making the base solution, I actually did rehearse this one, in the sense that I had actually carried out the steps in the video before. Not so much to improve the video, as simply following the instructions of the gurus on the mountains, so to speak; who recommend titrating 3 times to be absolutely sure of your results. It's no big deal to do it multiple times anyway, as it is a snap once you get everything set up.

I got the same results all 3 times, so there was no ambiguity there. I question the need for all the extreme accuracy though, because the experts can't even agree amongst themselves whether the correct amount of NaOH to use as a baseline should be 3.5 grams per liter, or 5 grams per liter. Both factions agree that extreme accuracy is necessary, they just can't agree on a starting point. Both factions do agree, however, that either starting point will work.
Allow me to point out that this 1.5 gram discrepancy covers quite a bit of inaccuracy in the titration process! In other words, we don't have to sweat it too much. Our "possum ugly" style of doing things should yield results that are indistinguishable from that of a professional-appearing laboratory, because of that built-in discrepancy!
Also, since I'm on the subject, I want to reiterate (and expound on) something I mentioned in the post about making the base solution (man, was that a fumble-fest!). Everything I read about making the solution stressed absolute accuracy in measuring the NaOH into the liter of water. What they didn't mention is that the stuff will be absorbing moisture from the atmosphere, getting heavier as you fumble around, trying to get it just right. Here's what I learned/figured out: Exact scales and graduations are irrelevant, so long as you use the same measurements throughout the process. If I take this mayonnaise jar and make an arbitrary mark on it with my magic marker at a point that "looks right", then use that mark to measure distilled water to pour into another jar; and then I make a couple of little dippers that each hold the same-sized two finger pinch of water, and use those dippers to measure the powdered base into the water, and later to measure the alcohol, base solution and oil into the test solution, and then later yet use the same dipper and jar with its measuring mark to measure the oil, methanol and base powder, I may not be able to articulate a name for those measurements (other than "jar" and "dipper"), but my proportions will be correct, anyway.

I think the process of titration is a stumbling block for a lot of people who would otherwise experiment with producing their own biodiesel. I know it was for me,initially. After all, the actual production process is not that much more difficult than simply mixing the vegetable oil with a certain proportion of gasoline, or kerosene, or petrodiesel, or mineral spirits, or acetone (all popular additives for viscosity reduction). The difficulty is in knowing how much base to add. Even the alcohol is added at a standard 20% proportion, so that's no real problem.

I must admit, I considered just skipping the titration process altogether, and guessing at 8 grams of NaOH per liter of oil. I'm glad I didn't, because that is exactly the number I came up with when I titrated! So when everything worked fine, I would have been tempted to conclude that titration was unnecessary after all. I may eventually arrive at that conclusion anyway, settling instead for a 1-liter test batch anytime something changes in my oil supply, but only after I titrate every batch for awhile and see how much the ph changes from batch to batch. I much prefer to know what I am doing, rather than guessing about it.

It's kinda' fun anyway, playing around with all this chemistry. Next up, actually producing some biodiesel!

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