Making biodiesel from waste vegetable oil is done by adding lye (NaOH) and methanol to waste vegetable oil to separate the free fatty acids, producing glycerol (soap and methanol) as a bi-product. It is suprisingly not so difficult to make biodiesel on a personal scale even for nonchemists. Homebrewed biodiesel can easily offer respite to visiting fuel stations for anyone inspired. Home processing kits can be 5-gallon bathtub style to primo automated self contained made-to-order units.
By demonstrating the titration test and processing a 1-liter batch in a soda bottle we hope to demystify the steps required to successfully make homebrewed biodiesel for anyone starting out. These are common test batch practices and basic techniques that are utilized by even the most seasoned bio makers. But before we begin,...our "we are not experts, yet disclaimer." Though we have made biodiesel repeatedly - pouring through many web sites, rereading a couple books and picking brains.
We dumpster dove much of our processor set-up, scoured our small town hardware stores and ordered stuff over the internet that we had never heard of before to assemble our very basic bio adventure. A growing network of information is available on the internet with site after site sharing their knowledge, recipes and experiences with links to suppliers of materials and kits for homebrewing. Some of our favorite sources so far have been journeytoforever.org, biodieselcommunity.org and some youtube.com videos.
After reading as much as you like, to understand the process truly its hands-on. Repeated titrations and
1-liter test batches are a must to familiarize yourself with all its variables. The learning curve is immediate with gratifying ahas. Good methodology to suit your space develops with these small batches. Somewhere between 5 and 20 batches, you'll be saying a cohesive rock on! This one's going into the tank! And once you get a handle on the process of converting waste vegetable oil to biodiesel, you will be directed to the style of processor that will suit your future needs.
Step 1 - Titration - is the process of testing the used oil to determine the free fatty acid content. Virgin oil has a Free Fatty Acid (FFA) content of less than 0.1%. More free fatty acids are formed when the oil is used for cooking. By finding ph - acid-alkaline level of used oil you can determine the amount of extra lye needed for a complete reaction to remove the free fatty acids from the oil to produce biodiesel. (pH7 is neutral, lower values are increasingly acidic, higher than 7 is alkaline).
Materials used in titration -
*For good practice maintain a measuring device/funnel/stirrer for each different liquid that you can label and reuse without risk of cross contamination. for example our labeled droppers (oil, lye/h20) rest independently in glass jars on a shelf for reuse saving time, water and handling.
- lye (NaOH) and distilled water solution (made ahead simply by dissolving 1 gram of lye into 1 liter of room temperature distilled water - this is used as a reference tester for the titration process in small quantity so this diluted lye water liter will last through many many titrations.) Store your premixed lye/water solution in clean labeled glass jar(s) that you can easily dip a graduated syringe into and measure in increments of milliliters.
- waste vegetable oil, 1-milliliter
- phenolphthalein - an indicator, 2 drops
- isopropyl alcohol, 10 milliliters
- clean glass jar (jelly size)
- measuring cylinder (10ml.), graduated droppers (in milliliters - 1 each for alcohol and oil)
- stirrer, wood or plastic
Performing titration - wearing rubber gloves, eye protection and common sense..
- Mix 10 milliliters of isopropyl alcohol with 1 milliliter of waste vegetable oil in a clean glass jar standing in hot water. Stir until oil dissolves in alcohol.
- Add 2 drops of phenophthalein and stir.
- Add lye/water a few drops at a time keeping track of the amount. Stir as you go. solution will turn pink and hold for 10 seconds when you have reached the desired ph level. (it will change a fleeting pink that disappears with stirring until you have reached the ph range of 8-9.)
- Take the # of milliliters derived from the titration and add 3.5 (the amount of lye needed for virgin oil) this total is the number of grams of lye you will need to process 1 liter of the waste vegetable oil into biodiesel.(and this total is simply multiplied by the # of liters of waste vegetable oil to be processed in future larger batches.)
World Famous Dr Pepper Technique - Now with the results from titration, you are ready to make a small 1 liter test batch of biodiesel using what is known as the "world famous dr pepper technique," with a quick wash method. See www.biodieselcommunity.org/makingasmallbatch/
(We have also quickly drank soda we normally wouldn't for these test batch containers. Maine has 5 cents redemption, so you cant easily find them on the side of the street.)
But first...the standard warnings!
The process includes chemicals and personal responsibility with safety precautions are necessary.
Wear eye protection, rubber gloves long sleeves, trousers, and full shoes. Methanol is poisonous and can be absorbed through the skin as well as inhalation or consumption and it is also flamable. Lye can cause severe burns. And on the flip note, these are readily available products used daily - methanol is sold to fuel model airplanes and sold as HEET brand antifreeze and in gallon jugs piled on pallets in front of our local gas station next to the ashtrays, an additive for diesel engines. Lye is an every-day drain cleaner.
Materials and equipment for test batch -
- 1 liter of waste vegetable oil
- lye(NaOH) - 3.5 grams plus x
- methanol - 200 milliliters
- a clear 2-liter soda bottle with top, clean and dry
- measuring cup/graduated cylinder to measure out 200 milliliters methanol
- a scale that measures in increments of partial grams
- a glass jar with sealing lid (pasta sauce size) to mix methanol and lye
- 2 funnels
Processing waste vegetable oil -
- Heat oil to 212° f to remove water.(if water is present the oil will spit and pop)
- While oil is cooling, mix 200 milliliters of methanol with the required amount of lye, determined in the titration process to form the methoxide. Cap immediately and always use a glass container for this step because the lye will eat through plastic as it dissolves in the methanol) dissolve lye in the methanol by swishing it around in the jar.
- After oil has cooled to 130° f (methanol evaporates at 148° f so it is imperative to begin processing under that temperature) pour oil into a 2 liter bottle using a funnel.
- Add the lye/methanol mixture to oil and cap.
- Gently roll contents around for 20 minutes and then let it rest for 24 hours. Within minutes glycerine and methanol will settle to the bottom with biodiesel on top and the dark brown color
Shake test -
Before washing you can check the quality of your reaction with a shake test. Pour off approximately biodiesel and add room temperature water in a smaller clear soda bottle and shake vigorously. If your reaction wasn't complete...the contents will congeal and turn creamy cloudy. If the reaction was good your biodiesel will maintain a golden color and the water will remain separate and it will start settling out as soon as the bottle is resting.
After reassurance through a shake test of your product, it is ready to "quick wash" -
- Pour off the remaining biodiesel into another 2 liter container slowly to maintain the separation leaving as little of it remaining with the glycerol as possible without pulling any of the glycerol with it.
- Add 500 milliliters of body temperature water and gently rotate bottle end for end for one minute and let it sit to separate which should begin immediately. that is the first wash. Let it settle 15 minutes.
- Repeat process by pouring off the biodiesel into another container carefully separating it from the water remaining. add 500 more milliliters of water shaking a bit more vigorously with each successive wash and let settle. With each washing the water becomes clearer.
- Repeat the wash process a total of three to five times and separate biodiesel from its last bath water into a container. It is fully washed when the water that separates reads a neutral of ph7. It will have lightened in color and after a day or two of drying (lid off) it will clear completely. (You should be able to read newsprint through it easily.)
Final notes - Biodiesel making can be messy very easily. Think containment for unavoidable drips and spills when setting-up your work area - plastic sheeting, cardboard, kitty litter, etc. Label everything and keep a notebook of your progress and all the questions that will arise. Stressing, these instructions are written with brevity, there's lots more stuff we could ramble on with.
Check out our budding biodiesel site at www.ganlanmeng.cn
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