An Introduction to Biodiesel

First things first: the information contained below on making biodiesel is not meant to provide you with a complete and thorough enough education on the subject for you to go out and make your own biodiesel without any further study. It is imperative that you recognize from the outset that making biodiesel involves chemicals and chemical reactions which can be quite dangerous if dealt with improperly.

With that in mind, please consider the following to be a general introduction to the process of making biodiesel, with the implicit agreement that if you decide to make your own biodiesel, you do a bit more research on the subject before beginning.

That said, we start with your ingredients, divided into the stages of the process of making biodiesel in which you will need them:

Mixture

• Waste Vegetable Oil (WVO) – used cooking oil, lard, animal fat, fryer grease;

• Sodium Hydroxide (NaOH) – that’s lye or caustic soda, dry only;

• Methanol (CH3OH) – at least 99% pure;

Titration

• Isopropyl/Rubbing Alcohol – again, at least 99% pure;

• Phenolphthalein Solution – kept out of the sunlight and no more than 1 year old;

• Distilled Water;

Washing

• Water

• Vinegar

Here is a brief rundown of the process of transterification, also known as making biodiesel:

1. Filter WVO; Warm it up to about 95° F or until it runs freely. Then run it through a canteen- or restaurant-type coffee filter or a double layer of cheesecloth set into a funnel. This removes any food scraps and other solids.

2. Remove water; This is an optional, but highly advisable, step in making biodiesel. Leaving in the water in your WVO can slow down the chemical reaction and cause the formation of soap. Heat your WVO to 212° F (100° C) and let the water boil off. As the boiling begins to slow, raise the temperature up to 265° F (130° C) and let it stay there for 10 more minutes. Then remove it from the heat, and set it aside to cool.

3. Titration (revealing how much catalyst will be needed); This is an integral step in making biodiesel as it will tell you how much sodium hydroxide (lye or caustic soda) you’ll need to use. It is this step alone that is the most critical and complicated part of making biodiesel, so do not begin until you feel confident that you understand titration completely.

In summary, you’ll make a solution out of 1 g completely dry lye thoroughly dissolved in 1 l distilled water. Being vigilant that this sample remains uncontaminated, place it in a reaction vessel where it can be warmed and stirred.

Meanwhile mix in a separate container 10 ml rubbing alcohol and 1 ml of your filtered, heated, and cooled WVO. Add 2 drops phenolphthalein (a pH tester indicating the acidity or alkalinity of a given substance).

Now’s where making biodiesel gets really delicate. You’ll next add a single drop at a time of this mixture into your mixed and heated titration sample, keeping careful count of each and every drop. You’re looking for the combination that gives you a pH of 8-9 (a light purple color).

A mathematical equation comes next, in a nutshell:

• # of ml titration derives X # of liters of WVO being transterified + 3.5 g lye for every liter of fresh (unused) vegetable oil to be used

Then, once you’ve determined the ratio, do the titration again to confirm your results. Remember, measure twice and get the mix right the first time.

4. Prepare Sodium Methoxide; Mix an amount of methanol equal to about 15-20% of the weight of your WVO with sodium hydroxide (lye) to make sodium methoxide. If the previous step was the most complicated and intricate, this step is the most dangerous. Avoid inhaling any vapors and protect your skin, which this chemical can burn.

Also be careful what type of container you use to hold your sodium methoxide mixture as it can corrode paints, while lye reacts poorly with tin, zinc, and aluminum. For the purposes of making biodiesel, stick with glass, stainless steel, or enamel.

5. Heat WVO again, stirring in Sodium Methoxide; Heat WVO to 120-130° F and mix in Sodium Methoxide stirring (preferably with a machine like a paint stirrer) for the better part of an hour.

6. Let the biodiesel mixture settle (removing the glycerine); Making biodiesel properly requires that you let it sit and cool for no less 8 hours. Your mixture will separate into 2 layers:

• your esters (biodiesel)

• soap (waste)

7. Wash and dry biodiesel; Removing the soap waste.

8. Check the quality of your biodiesel

See our companion article to “Making Biodiesel” on “How to Test the Quality of Biodiesel [http://biodiesel.biogreenlife.com/20/how-to-test-the-quality-of-biodiesel/]”.

Once you make your own biodiesel for the first time, you will surely discover how rewarding an experience it can be. And once you start using the biodiesel you make, you’ll find it even more so. Making biodiesel can liberate you from oil dependency and rising gas costs. Just remember to learn more about the process than the summary information contained in this article before you get started making biodiesel for the first time.