How to Titration

Titration is an indirect test for free fatty acids (FFA)

Each titration only takes about 30 seconds although it looks terribly complicated 'on paper'. Titration is done by reacting a small sample of oil with a measured amount of lye, and using pH to tell us when the FFA is all used up.

Why We Titrate

The biodiesel reaction needs alkaline (NaOH) or KOH, as a catalyst  Waste oil contains free fatty acids (FFA), and the free fatty acids will with lye to make soap before the lye has a chance to participate in making biodiesel.

We do a titration to find out how much free fatty acid is present and to find out how much to compensate for it by adding more lye so there's some left for the desired biodiesel reaction.

How to Titrate

The titration performs the lye/free fatty acid reaction on a very small scale, and we use pH to measure it (somebody before us has previously figured out which pH change indicates that this reaction is complete, and it's at pH 8.5, the colour change point of phenolphthalein indicator. Phenol red or Turmeric is close enough and is a store item).

How to Use

The Biodiesel Titration Kit Includes: 

Scale - 5g x 0.01g

Magnet strri hotplat

3x 100mL Graduated Beakers

1000 mL Cylinder 

Small Funnel

2 off 2 ml pipets

2 off 10 ml pipets

2 off 25 ml pipets

Titration Instructions

Dissolve 1 gram of lye in 1 litre of distilled or de-ionized water (0.1% w/v lye solution) (weight to volume).

A blank titration

Sometimes alcohol becomes slightly acidic with age, which would throw off your results. So we test it by performing a blank titration periodically. A blank titration looks just like a regular titration but without the oil. A blank titration neutralises any acids that the isopropyl contained, so you're starting with a 'blank' slate and your real titration only reads the free fatty acids instead of the acids in the isopropyl.

Performing a "Blank Titration"
1. Measure 10 ml isopropyl alcohol into your titration vessel.
2. Add several drops of turmeric indicator solution until the alcohol turns yellow.
OR Add just enough drops of lye solution* until you see a 30 second colour change.

Titrating WVO
1.  To 10 ml. isopropyl alcohol you have neutralized in a "Blank Titration" add 1 ml. WVO
2.  Mix thoroughly (it will turn yellow)
3.  Add a known amount of lye solution until you see a 30 second colour change
4.  Record the amount of lye solution you used
5.  Repeat Steps 1 through 4 until you repeat your results two more times

Add 10 ml of isopropyl to the beaker add a few drops of phenolphthalein, phenol red or bit off Turmeric Swirl. It'll be turn into sort of yellow pink colour then measure an exact 1 ml of oil with a syringe or pipette, into a jar (or beaker) with about 10 ml of isopropyl alcohol. Measure the oil with a different syringe or pipette than the isopropyl. The amount of oil is very crucial, but the isopropyl isn't. You can mix into the same liquids as you did the blank titration on. The liquid will be yellow after you've added the oil. In very cold weather, please warm the oil to 40c

 Add and Measure Lye/Water Solution:
Now, add to this 'beaker', a very small amount of the lye/water drop by drop (or KOH/water) solution that you'd already made- keep adding in tiny increments (and keep track of how much you're adding), and swirling the contents, as you keep adding, it'll start to show a change to pink, but will revert back to yellow as you swirl Once it's uniformly pink and stays that way for at least 30 seconds, stop adding lye/water and count how many millilitres you've added.

Phenol red and phenolphthalein or turmeric will stay pink for different amounts of time- the phenol red will usually turn yellow after a minute, but the phenolpthaleine and turmeric will stay purple.

Now, clear out the beaker and do this again 3 or 4 time. Try to get the same result more than once in a row- it's easy to make mistakes when measuring such small quantities of liquids or take the average reading of three tests you do

Calculate
how much lye/water did you use? This is the point when all the FFA was neutralized by the lye from the lye/water.

Each 1 ml of lye/water corresponds to 1 extra gram of lye you'll need to add when making your litre batch, just to eliminate the free fatty acids in that oil. If your oil takes more than 4 ml of lye or 5 ml of KOH (potassium hydroxide), don't use it until you gain more experience. 'Average' restaurant oil will require about 3 ml on the titration, and really bad fast food grease can take 5 or so, which is completely unusable with NaOH (sodium hydroxide) or KOH (potassium hydroxide) catalyst.

Please note that the titration should be done with the same catalyst you're going to use to make your fuel, use that to make your lye/water mixture, and if you're using NaOH (sodium hydroxide) or KOH (potassium hydroxide), use a gram of that NaOH (sodium hydroxide) or KOH (potassium hydroxide) to make water/NaOH (sodium hydroxide) or KOH (potassium hydroxide) mixture

A biodiesel processor make more than one litre at a time, you still need to know how many litres of oil you're using. Calibrate your processor in litres. To find out how much catalyst to use, you will multiply the following:

For NaOH (sodium hydroxide)
number of litres of oil x (5 grams plus titration results)

Example:

If titration showed 2 ml that translates to 2 extra grams for each litre of oil I'm reacting to make biodiesel. If I'm reacting 100 litres of oil I do the following math:

100 litres oil x (5 grams NaOH (sodium hydroxide) + 2)

100 x 7 = 700 grams NaOH (sodium hydroxide) needed to make biodiesel with this oil

For KOH (potassium hydroxide)
when using KOH, you do the same thing. The titration results with KOH/water will be slightly different than the results you'd get with NaOH in the water. However you still use them the same way = 2 ml on the titration = 2 extra grams of catalyst added to the processor. Using KOH instead of NaOH you also need to use a slightly different 'base' quantity for the reaction itself- 7 grams per litre instead of 5 grams per litre.

Example:

100 litre processor, KOH (potassium hydroxide) catalyst, and titration which showed 3.8 ml for that oil:

100 x (7 grams KOH (potassium hydroxide)   plus 3.8 ml)

100 x 10.8= 1080 grams of KOH (potassium hydroxide) for this particular oil

To confuse matters further, KOH (potassium hydroxide) comes in a variety of purities. You want an 85% or higher I think. However for beginners I recommend just buying the 99% pure adjust your KOH levels to compensate for impurities (i.e. if you've got 90% pure KOH use 10% more of it). Do not adjust the results of the titration! The titration will automatically reflect the impurity level for you. Realistically I don't think all of this is a very big deal, though

Catalyst Quantity:
Many other instructions for making biodiesel use a lot less base catalyst than I list here. That is because the amount of catalyst we home brewers use is a sort of compromise between two desired outcomes.

The biodiesel industry tends to use a lot more (for the catalyst, not the 'titration') - 1% by weight or about 9 grams per litre. The more catalyst you use, the better the quality of the biodiesel (see next month's Energy Self-Sufficiency Newsletter article, which will be about quality testing) up to a point, but the tradeoffs is that more catalyst causes more soap to be produced. So many homebrew recipes recommend 3.5 grams per litre for NaOH or 4.9 grams per litre for KOH, which are tradeoffs to reduce soap formation. Catalyst is not the only factor which influences quality, so people get away with successes and failures using both amounts. Generally if I am working with high-ffa oil (over 4 ml on an NaOH titration, or thereabouts) which is more likely to make 'glop', or if I'm working with oil that tested high in water and which I have not dewatered (see the webpage on testing for water in oil) then I begin to think about compromising and use a smaller quantity of 'base' catalyst (i.e. closer to that 3.5 grams NaOH that others may recommend). I'm not sure yet whether this really helps. If you can keep your titration measurements accurate, though, you'll reduce the variables and make it easier to troubleshoot any problems you may encounter.

Improving Accuracy of Measurements:
If you want to get really accurate with titration, one way to do so is to work with larger amounts of chemicals at a time- 4 ml of oil instead of 1 ml- and to divide the result by whatever percentage you used (i.e. 4 ml of oil will yield an acid number 4 times larger than 1 ml of oil will, so to find out how much extra alkali to add to the litre batch, you divide that number by 4)

You can also make improvements by measuring more than 1 gram of alkali for your initial lye/water or KOH/water solution. It can be done in a variety of ways but I recommend just using 3 litres of distilled water and measuring 3 grams of lye or KOH.

Others recommend adding 10 grams lye to 1 litre of water to make a stock solution, then measuring out 100 ml of stock, and diluting it into a working dilution with 900 ml of water.

More about this titration:
If you're still confused about this stuff, please check out a couple of other people's explanations

Biodiesel refers to a diesel-equivalent processed fuel derived from biological sources (such as vegetable oils) which can be used in unmodified diesel-engine vehicles. It is distinguished from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some diesel vehicles. 

You will need:

• fresh or used vegetable oil (filtered)
• sodium hydroxide   (NaOH) or Potassium hydroxide (KOH)
• methanol
• isopropyl Alcohol (for tests use 99% IPA)
• pipette- or other type of 1 millilitre dropper
• litmus paper available to test for PH level
• plastic or glass measuring cups or beakers, with metric measures and a gram scale
• plastic, glass or stainless stirrers and spoons,
• plastic buckets
• rubber gloves, safety glasses, plastic apron

　Transesterification for Wasted Vegetable Oil (WVO)

        Vegetable Oil: Diesel has a chain of 11-13 carbons, and new vegetable oil has a chain of about 18 but wasted vegetable oil which has been heated has chains of up to 32 carbons. To burn in an engine, the chain needs to be broken down to be similar in length to diesel

         Lye: (Sodium Hydroxide ((NaOH) or potassium hydroxide (KOH) also works) is the catalyst for transesterification. It works by "cracking" the vegetable oil molecules, splitting the triglycerides from the hydrocarbons and shortening the carbon chain. (min of 3.5g or .35% is the standard amount of lye necessary to create a reaction, when using fresh vegetable oil, so you can figure that used vegetable oil will always use more and how powerful of the pump your use)

        Methanol: The amount of methanol needed will also vary, but the ideal is to use the least amount of methanol necessary in order to get the highest yield. The yield is related to completion; so if you get a 90% yield that means that 90% of the fatty acids have been eliminated from the vegetable oil. We have found that the best is to use min of 15% to 20% methanol, based upon the total weight of your batch of oil.
　

       A hydrometer can also be used to check the amount of completion according to density

• Vegetable Oil has a specific density of .910

• Biodiesel has a specific density of .850-.870

Example test

Using WVO

WVO heated in a reactor up to 40-50C degrees

1.    In separate container mix 20% of  Methanol (MeOH)

2.    Add the NaOH/KOH dissolves slowly! It will become extremely hot, and on a larger scale potentially dangerous.

This combined mixture makes Sodium Methoxide.

Add this to the WVO and mix for 40-60 minutes mixing

NOW pump out the oil to second tank let the mixture settle for at least 4-8 hours, check the rate of separation. The cloudy looking free fatty acids, called glycerine, will sink to the bottom and the biodiesel (methyl esters) a translucent liquid, will remain on top. When the separation appears not to be advancing any more stop 

The liquid you have on top now is biodiesel (methyl ester), but before using it you have to remove any remaining soaps or salts which could cause engine damage. The glycerin which has sunk to the bottom of the tank should be pump out disposal off.

Then Washing

Example test 5% water

Methods
the catalyst NaOH/KOH is dissolved into the alcohol Methanol (MeOH) by vigorous stirring in a small tube.

the oil is transferred into the biodiesel reactor oil is heated in a reactor up to 40C degrees and then the catalyst /Methanol mixture is pumped into the oil and the final mixture is stirred vigorously for 1 hours. A successful reaction produces two liquid phases: biodiesel and crude glycerol. Crude glycerol, the heavier liquid will collect at the bottom after several hours of settling. Phase separation can be observed with in 10 minutes and can be complete within 2 hours of settling. Complete settling can take as long as 20 hours.

After settling is complete, water is added at the rate of 5% percent by volume of the oil and then stirred for 5 minutes and the glycerol is allowed to settle again. After settling is complete the glycerol is drained off the biodiesel layer remains.

Washing the biodiesel ester is a two step process which is carried out with extreme care. A water wash solution at the rate of 30 percent by volume of oil and 1 gram of tannic acid /per litre of water or Just add a little 10% phosphoric acid (H3PO4) to the washing water first, 2-3 ml/litre, just to be on the safe side, I don't want any lye floating around  layer very gently. This process is continued until the ester layer becomes clear. After settling the aqueous solution is drained and water alone is added at 30 percent by volume of oil for the final washing.

Washing biodiesel : So it can be washed free of any remaining soaps, salts or free fatty acids.

Bubble washing : The bubble washing technique was the most economical way of washing biodiesel after processing. The pumps use only a few watts of electricity (your mixing motor may use 250 to 300 watts) and you need only use 50 to 75% ratio of water to biodiesel to wash, as opposed to three or four times the volume of water in the more usual mixing wash metho

Very slowly add water to the bottom of the tank, Use the Bubble wash method, Use one-third the volume of water as the amount of biodiesel to be washed. Make sure both the water and biodiesel are roughly the same (room) temperature, then put in the aquarium stone and start the air pump. Let it bubble for 3-4 hours minimum. Turn the pump off and let the mixture settle for half an hour. The water will fall to the bottom, turning completely white, and the fuel you made will be much lighter in colour now. Drain the water off, repeat the procedure two more times. Remove the biodiesel from the tank, taking care not to get any water with it then allow mix to settle. When the water has cleanly separated from the biodiesel, drain or pump the water out from the bottom. Repeat until the discarded rinse water reaches ph level of 6-7 and no soap bubbles appear.

If the liquid is cloudy, there is water being retained in the fuel, and it will need to be reheated slowly to evaporate out the water. Any white substances forming at the bottom or any bubbles forming at the surface is a sign of soaps and should be removed or the liquid should be re-washed. The cleaned biodiesel are now a homemade version of biodiesel and are ready to go into your diesel tank.

It is recommended to use a percentage of diesels with your homemade fuel at least 20% or more.

OR

Mixed washing the biodiesel: add 30% water to the tank turn the pump on mixed very gently for 1-3 min first time. then  2 rd add 30% water to the tank mixed for 3-6 min. 3 rd add 30% water to the tank mixed for 5-10 min then spray dry the oil　

Spray washing the biodiesel: Water is sprayed miser at low velocity on top of the tank of biodiesel. The water will wash away any excess alcohol and catalyst. It will emulsify somewhat with the biodiesel. The less this is agitated the better as agitation will cause more emulsification and less useful biodiesel. Let this sit for 24-48 hours until the water has settled.