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<\/a>Two fish and one scoop of chips for me, and the leftover oil for my car, thanks.<\/p><\/div>\n
Ingredients:<\/p>\n
- \n
- 1 litre of filtered vegetable oil plus 1 mL for titration<\/li>\n
- 200 mL of methanol (this is the hardest ingredient to get hold of)<\/li>\n
- 10 mL isopropyl alcohol (for titration)<\/li>\n
- sodium hydroxide (caustic soda \u2013 try a hardware store)<\/li>\n
- water (for the titration)<\/li>\n<\/ul>\n
First comes the titration.\u00a0 Mix up the caustic soda: 1 gram to 1 litre of water.\u00a0 To work out how much caustic soda solution you need, put 10 mL of isopropyl alcohol and 1 mL of oil in a beaker.\u00a0 Use an eyedropper to add the caustic soda 1 mL at a time. Check the pH using litmus paper or one of those testers you get at swimming pool supply places after every mL of caustic soda. When the pH gets to between 8 and 9, you\u2019ve hit the right spot.\u00a0 Count the number of mL of caustic soda you used and use the following formula to calculate how much you\u2019ll need to make your biodiesel: number of mL + 3.5 = N<\/i>. N is the number of grams of caustic soda you\u2019ll need for your batch of oil.\u00a0 Use leftover caustic soda solution for cleaning the drains or making soap (and for goodness sake, label the container with a large warning label!)<\/p>\n
Put your vegetable oil into one container and your methanol into another.\u00a0 Put N grams of caustic soda in a dish.\u00a0 Now you\u2019re ready to get started.\u00a0 Make sure that the containers you use are a lot bigger than the amount of oil you\u2019re working with in case things foam up when reacting. \u00a0In the article I read, the people used 3-litre plastic bottles for mixing the oil and caustic soda\/methanol solution to avoid problems with fumes, shaking the mixtures gently to stir them. \u00a0You may or may not need to warm the oil gently \u2013 some of the many websites about making biodiesel say you do need to but others don\u2019t.<\/p>\n
Step 1 is to stir the caustic soda into the methanol.\u00a0 Stir well but don\u2019t breathe the fumes in.\u00a0 Don\u2019t touch the container, either, as this reaction gives off heat.<\/p>\n
Step 2 is to carefully add the oil to the soda\/methanol mixture.\u00a0 Stir well again.\u00a0 Be prepared for the mixture to react.\u00a0 (My eyebrows went up when I read this instruction \u2013 all the soapmaking recipes I\u2019ve read, which also involve caustic soda and fat, tell you to add the caustic soda solution to the oil).<\/p>\n
In Step 3, you leave the mixture to settle.\u00a0 Leaving it overnight is best.\u00a0 When you come back the next morning, you\u2019ll find a layer of glycerine down the bottom and the biodiesel up the top.\u00a0 The longer you leave it, the better.<\/p>\n
Step 4 is the tricky bit: separating the glycerine from the biodiesel.\u00a0 Let the glycerine dry out a bit and use it for soap.\u00a0 The biodiesel goes into your fuel tank.<\/p>\n
If you use too much caustic soda, you\u2019ll end up with soap, which isn\u2019t a total disaster!<\/p>\n
If you try this, let us know how you get on.<\/p>\n
Happy driving,<\/p>\n