Biodiesel Journal

These are the major fattyacids that the two main vegetable oils Soybean and Canola contain in their triglycerides on the left. The main sequence of making biodiesel is seen below on the right.

It is 3/13/2011 and I have made about a liter of biodiesel. The major results were:

  1. Any oil works. If it has many triglycerides in it, it is fit for transesterification.
  2. Sodium Hydroxide is very dangerous, use safety gear and ventilated area.
  3. 200mL of methanol and 5.5 grams of NaOH for every liter of oil. 7.5 grams for KOH.
  4. The NaOH needs stirring to dissolve in the methanol.
  5. Heat the oil, but not above 55 Celsius before starting the reaction.
  6. Shake vigorously for ten minutes and let set. If possible use a mixer or a blender for a good hour before letting set.
  7. Glycerin settles in the bottom, biodiesel on top.
  8. Poor results include saponification where a bunch of cloudy soap forms from excess water.
  9. Wash the oil by spraying it with water and letting it separate. This cleans out the excess methanol.
  10. The 27/3 test verifies your results. Take 27mL of methanol and 3 mL of your product, mix and shake. The settled result should be clear, not cloudy, showing minimum di and triglycerides.

Pictures of results

Below on the left is a batch going in the blender for 15 minutes. It is just NaOH dissolved into methanol, then poured into vegetable oil. The next one shows what happens after you let it sit for a few hours. The top layer is the biodiesel. The bottom layers are a combo of gel biodiesel and soap and glycerin. The  third from the left shows what happens when you include too much air and turbulence in the water washing process.  The last one has been washed correctly.

Here are some other types of oil that produce the same results.  From left to right they are corn, grapeseed, canola/soybean mix, glycerin swamp and peanut.

On the left is centrifuged oil from a restaurant, it is watery and dirty with unwanted microsopic sludge.  In the middle I finally was able to get a good result using potassium hydroxide. After biodiesel conversion and careful washing with water it becomes much cleaner and leaner, seen on the right.


Tips from the Masters of biodiesel in Utah - Common Problems

  1. Using oil that is too wet - Oil water content should be 1500 PPM (0.15%) or lower
  2. Using oil that titrates too high - Anything over a 6 using NaOH based titration can be a pain
  3. Not mixing oil/catalyst/methanol long enough - Depends on reactor, but at least 2-3 hours is standard practice
  4. Not heating up oil hot enough or too hot - Heat should be between 130-140 deg. - Too hot may boil off methanol, too cold may not allow the reaction to happen in a timely manner
  5. Using methanol that isn't pure or catalyst that has gone bad (carbonated) - Methanol should be at least 99.5% pure for mixing catalyst - If catalyst has chunks in it, throw it out. It's carbonated (mixed with the air)
  6. Not measuring correctly & also not performing any tests before progressing - Can lead to not adding enough or adding way too much - Washing a batch that doesn't pass 3/27's can lead to emulsions - Making Bio w/o titrating can lead to issues as well
  7. Not adding enough catalyst because a titration wasn't done right - Leads to under-reacted fuel, 3/27 will indicate if conversion has occurred or not
  8. Referring to Journey To Forever for most Biodiesel recipes (especially acid esterification) - Most information found there is terribly outdated and doesn't ever seem to be updated
  9. Not mixing oil long enough when doing acid esterification - 6 hours of mixing is usually a good minimum, the longer the better
  10. Not being patient enough and washing too fast, not draining off all the glycerin, or trying to use the fuel before it's been completed - Add the methanol too fast and it might not mix properly - Shut the pump down too soon and full reactions may not occur - Draining glycerin too soon may lead to additional glycerin falling out later - Wash the fuel too aggressively and you'll get emulsions - Attempting to dry fuel not properly washed can lead to soap ending up in finished fuel

Titrating oil

To make biodiesel from waste vegetable oil efficiently you first must measure the level of acidity due to the broken triglycerides from the cooking. Litmus paper does not work well in this case so we turn to a rigorous titration method.  The sample on the right passed at 7mL, that is a sign of a high concentration of free fatty acids.

  1. Take 1 mL of your WVO in a small vial.
  2. Prepare the titration solution, 1 gram KOH or NaOH to 1 Liter of distilled water.
  3. Mix the 1 mL of WVO in with 10 mL isopropyl alcohol and mix it up
  4. Add 3 drops of phenolphthalein, pH indicator
  5. Prepare a syringe of 10 mL titration solution
  6. Add to oil/alcohol/phenolphthalein until the sample turns pink
  7. Make sure it stays pink for at least 30 seconds
  8. Record amount of titration solution used, a
  9. Repeat more times and take average for more accuracy
  10. Calculate the needed amount of catalyst per mL of the WVO with the formula: i=a+7.5 g

27/3 Test for ASTM standard biodiesel

ASTM(American Society for Testing and Materials) D6751 - 11 Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels.  The sample on the right below is one that barely passes with minute emulsions of triglycerides in the bottom as the arrows shows.

  1. Mix 3 mL of your biodiesel in with 27 mL of methanol
  2. Let it set for 10 minutes
  3. If the biodiesel dissolves well into the methanol you get a single clear phase of molecularly suspended fatty acid methyl esters in the methanol
  4. If the sample become cloudy it means triglycerides are still prevalent in the sample. The biodiesel did not completely dissolve as there are blobs still floating around and glycerin at the bottom. This indicates substandard ASTM biodiesel.

Ethanol biodiesel

Instead of using methyl alcohol as the ester source, I tried denatured ethyl alcohol to see what would happen.  The ethanol has not yet been seen to create a phase.  I would imagine a diesel engine would eat this stuff up whatever it is:)

Tim Wendler timoth500@yahoo.com

Manuel Berrondo   Jean-Francois Van Huele   J. Ward Moody   Scott Bergesen  Gus Hart