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BioDiesel Class 101

Class # 3 - Titration

    Titration is a very simple chemical test with a complex sounding name. This test is done to determine what the pH balance of the material in question is at, in layman's terms, how acid or base the item is.

    The Transesterification process requires a slight Base pH condition. Since we use WVO, it is important for us to check the pH of the oil because the act of heating & cooking food with an oil produces acids called FFA or Free Fatty Acids. As the FFA accumulate it causes our WVO to become more & more acidic over time. If Transesterification occurs under less than ideal pH conditions we will produce less BioDiesel methyl ester & have left over unconverted fats or if we use too much Lye we will make excess soap. The process will always produce some soap, we just want to keep it to a minimum. Common pH test strips are not sensitive or reliable enough for making testing the pH with & it is questionable if a pH electrode would work well or very long when contaminated by oil, so that leaves us with the cheap but simple test called titration. We give more details than those contained below in our PGB book.

    To titrate you use a simple pH indicator solution such as phenophaline solution or red cabbage juice to give an indication how acid or base a solution is by color change. You also use a standardized (Lye) reference solution to determine how much Lye you will require.

How to Titrate (basics)

  1. Get some Iso-Heet brand isopropanol alcohol & measure out 10ml into a clean baby food jar.

  2. Place 3 drops of pH indicator solution such as Phenophaline solution into the alcohol in the jar & mix well.

  3. Start adding .1% Standardized reference solution drop by drop into the prepared alcohol/phenophaline mixture. Swirl the mixture as you add in the reference solution & watch carefully for a pink color change, stop adding the solution as soon as this occurs. This neutralizes any acid in the alcohol.

  4. Now measure out 1ml of the WVO to be tested & place it into the baby food jar with the alcohol mixture. You want this mixed up very well so make sure you swirl or stir it up until the alcohol & oil are totally mixed, this is very important!

  5. Once mixed, start swirling the mixture while you ad in the standardized lye solution drop by drop. You want to count the number of drops it takes to make the solution change it's color to pink for 10 seconds. Each 1ml of standardized solution used equals 1 gram of Lye to be used per liter of WVO you wish to process.


Brand new vegetable oil does not contain FFA from cooking so it does not need to be titrated because it has not been used to cook with & we know the ph. The amount of Lye required to reach the pH needed to process new oil into BioDiesel is between 3.5 & 5 grams of Sodium Hydroxide per Liter of oil. When using WVO, you take the number that it titrated at & add between 3.5 & 5 grams to this number, you then multiply this number times the number of Liters of WVO that you intend to process & this is the weight in grams of Sodium Hydroxide you will require to make your BioDiesel.

And you thought we forgot.....

  1. What does Titration do?

  2. Name 2 pH indicator solutions?

  3. What are you really doing when you Blank the solution?

  4. What does FFA mean?

  5. How many seconds does the standardized solution need to hold the pink color for in to know how much Lye to use per liter when making BioDiesel?

  6. What kind of alcohol is used when titrating?

  7. How many grams of Lye are required to convert the new base oil?

The next class Methoxide

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Last modified: 11/26/16