Lye (Catalyst)

Lye is the catalyst used for transesterification. It works by “cracking” the vegetable oil molecules, splitting the triglycerides from the hydrocarbons and shortening the carbon chain of 3.5gm or 0.35% is the standard amount of lye necessary to create a reaction, when using fresh vegetable oil. Due to the presence of a very small quantity of FFA we add an additional 0.3 to 0.4 grams in order to neutralize completely.


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 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 15% to 20% methanol, based upon the total weight of batch of oil.

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


• Weight 6 kg of vegetable oil (refined sunflower oil) and pour it into the reactor for preliminary heating to temperature of about 60-70°C.
• In separate container, dissolve 22.8grams of NaOH (3.8grams per liter of oil, got by 3.5grams stoichiometric equivalent and 0.3grams for neutralizing FFA) in 1.2L methanol (200ml per liter of oil) add the NaOH slowly. This combined mixture makes sodium methoxide.
• Add this to the vegetable oil. Provide rigorous mixing with the use of a stirrer.
• The cloudy looking free fatty acids, called glycerine, will sink to the bottom and the methyl ester- a translucent liquid, will remain on top.
• When the separation appears not to be advancing any more, stop mixing.
• Let the mixture settle overnight. Meanwhile another batch can be started as the reactor is not being used.
• The liquid on top is methyl ester, but before using it any remaining soaps or salts which could cause engine damage have to be removed.
• The glycerin which has sunk to the bottom can be used in production of cosmetics

Representative APR 391%

Let's say you want to borrow $100 for two week. Lender can charge you $15 for borrowing $100 for two weeks. You will need to return $115 to the lender at the end of 2 weeks. The cost of the $100 loan is a $15 finance charge and an annual percentage rate of 391 percent. If you decide to roll over the loan for another two weeks, lender can charge you another $15. If you roll-over the loan three times, the finance charge would climb to $60 to borrow the $100.

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