Titrating your oil:

 

Some Scientific crap for non-scientists!

Simply speaking, waste vegetable oil has some "bad stuff" in it that hinders the production of biodiesel.  This "bad stuff" consists of fatty free acids, food particles, water and other contaminates present from cooking the food in it. Pre-Filtering/ de-watering and settling the contaminates of the waste oil will go a long way in helping to perform a successful reaction.

To make Biodiesel, you have to identify how much Lye and Methanol to use to transesterfy the vegetable oil.  This "identification" process is called Titration.

The transesterfication process can be defined as : the  heavy alcohol bonded in the fat esters (Glycerol)  is replaced with a lighter one - Methanol.  The Glycerol precipitates to the bottom of your reactor and is drained off - leaving unwashed biodiesel. During the reaction phase, contaminates such as soap, monoglycerides and diglycerides are also formed as unwanted reactions.   Titration is done to determine how much methanol and Lye to use to minimize these "side reactions" and to give the best results of a mixture needed to perform the transesterfication process.

Esters (a class of acid chemicals) are bound to heavy alcohol (glycerol)-  and are chemically the building blocks of all fats.  The acids in the fats tend to give the fat its flavor and viscoscity/ solidity.  Vegetable oils are also constructed from esters and Glycerol.  

Biodiesel is made of 3 fat esters (triglycerides), but instead of them being bonded to glycerol molecules, they're bonded to another alcohol - Methanol.  Essentially in a nutshell, biodiesel is methyl esters.

To determine the amount of free acids inside your waste vegetable oil, we perform a "Titration" - nothing more than a chemical test that you'll do on a sample of the WVO oil that comes from your reactor (after you've brought the oil up to 200 degrees and boiled off any residual water and drained at least a liter from the bottom (for safe measures to rid  your reactor of  as much precipitated water as possible).

Phew... now that that scientific stuff is over with --- There is some dude on the internet that had his own buttocks liposuctioned , then  transesterfied it and ran his speedboat partially on "Ass diesel"- now that's a really dedicated Biodieseler!  What a great way to lose weight and solve our energy problems. Why bother drilling in Alaska when you can start with your own butt?-  Just look around at your local buffets-  America really does have some untapped reserves of fuel! :)

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Prerequisites

Chemicals needed:

Measurement tools:

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Procedures

Procedure to make an Alkali solution: (note you will only have to make this alkali solution ONCE - it will last for many titrations!)

  1. Pour exactly 1 litre of distilled water into a bottle that will hold it.
  2. Measure out exactly 1 gram of lye of your choice (on your small scale)- can be either KOH or NAOH
  3. Dump all of your 1 gram of lye in the 1 liter of distilled water into the bottle in step 1.
  4. Shake vigorously until all the lye is dissolved (shouldn't be that difficult)

Preparation for your Titration: (label your cups as described below!)

  1. Measure 50 milliliters of Isopropyl alcohol and put it into a cup (we will call this the alcohol storage cup)
  2. Measure 50 milliliters of the Alkali solution and put into another cup (we will call this the alkali cup)
  3. From your reactor (after it has been drained of 1 liter of its oil from the bottom of the tank and boiled/settled) remove 50 milliliters of  oil and put into a cup (your oil cup) - I usually heat the oil cup in the microwave for about 5 or 6 seconds to get it about 100 degrees farenheight  temperature for testing.

Titration cup

  1. Remove 10 millileters of the alcohol from your alcohol storage cup and place it into your fourth cup - (this is your titration cup)
  2. In your titration cup, add 3 drops of PH indicator and stir.
  3. Use a pipette or syringe or (empty eye drop bottle) suck up some of the alkali solution from your alkali cup (get it ready in hand to use)
  4. Take your titration cup (that has its 10ml of alcohol and 3 drops of ph indicator in it) and start swirling it in a circular motion.  Slowly add 1 drop of the alkali solution while continually swirling.  Keep slowly adding drops of alkali until you see a quick color change then -  STOP adding alkali solution!!! It should only take 1 or 2 drops of alkali solution - you'll see a quick flash of redish/pinkish color then back to clear!  (You have just performed a BLANK titration in your titration cup.-now the tiration cup is  ready to do our titration!)
  5. Using a clean pipette, remove1 milliliter of Waste Vegetable oil (from the oil cup)  and place that 1ml of oil into your titration cup. (stir it like crazy to make sure its mixed into the titration cup sufficiently - sometimes I'll suck in some of the titration cup's alcohol into the pipette i'm using for the oil to make sure every bit of oil is cleaned out of the pipette and resides in the titration cup.

Difficult part:

Here's where a good accurate digital pipette will really make your life easier - but you can do this with cheapo plastic pipettes and syringes instead if you're good with keeping track.  I've even heard of "counting drops" of solution from a recycled "Clear Eyes eyedrops bottle" to determine fluid amounts - but haven't tried it yet.

  1. Fill a syringe with 4ml of alkali solution.  When filling the syringe, leave a small air gap before you start sucking it into the syringe.  Look at the curve at the bottom of the air bubble and when that curve reaches 4ml, you've got 4 milliliters of alkali.
  2. Take your titration cup (still with its contents in step 5 above) and slowly add alkali solution from your syringe - drop by drop while all this time, stirring the mess together with a glass stirring stick.  When your solution first changes to pink, it will immediately go away with stirring this is your first "False indication" slow down on the addition of alkali because you're getting close!
  3. While really slowly adding alkali one drop then another in between longer stirring -  your solution will stay pink while your stirring and not go away!  STOP adding alkali and look at where your air bubble's curve is.
  4.  Perform a Math calculation of  (4 minus how much alkali you have left in the syringe) to determine what your titration value is!

Example:  If your syringe (or pipette) has 5 markings in between each of its ml graduations, each marking is worth .2 ml  {1ml/5graduations = 0.2ml per graduation}  So, if your bubble's bottom curve is exactly at the 3rd mark in between 0 and 1 ml, that means you have 0.6 ml left of alkali in the syringe or pipette.  Since you started with 4ml, {4 - .6}= 3.4  (In this case your titration value would be 3.4)

Easy now!:

I do the titration 3 times - each time just washing out and completely drying my 4th cup (titration cup)  to ensure my titration value stays consistent (to make sure I haven't breathed too many alcohol fumes) haha

Use this titration value for determining the amount of lye you'll need to add to your reaction, and plug this value into myTitration calculator here:   Matts Recipe Calculator