Glossary of Biodiesel Terms

Air Polishing: A final process in the production of Biodiesel. Air polishing is done by bubbling dry air through biodiesel to remove water or haziness, also known as air drying.
Biodiesel: An environmentally safe, low polluting fuel for most diesel internal combustion and turbine engines. Can be mixed with petroleum fuel and stored anywhere petroleum is. Made from fresh or waste vegetable oils that are a renewable energy source. Biodiesel is relatively safe and easy to process.
Bubble Wash: A method of final washing of biodiesel through air agitation. Biodiesel floats above a quantity of water. Bubbles from an air supply are injected into the water causing the bubbles to rise. At the water/biodiesel interface, the air bubbles carry water up through the biodiesel by surface tension. As the bubble reaches the surface and breaks, the water is freed and percolates back down through the biodiesel again. Simple diffusion causes water-soluble impurities in the biodiesel to be picked up in the water and removed.
Catalyst: A substance that accelerates the rate of a chemical reaction without being consumed in the reaction. In biodiesel production NaOH and KOH are the catalyst for transesterfication.
Crude Glycerin: The waste byproduct of the biodiesel making process. It is primarily made up of about 1/3rd Glycerin, 1/3rd Salts & Methanol and 1/3rd Unidentifiable Sludge.
Emulsification: To emulsify, to form an emulsion.
Emulsion: A suspension of small drops of 1 liquid in a 2nd with which the 1st will not mix. Emulsions can be formed either by mechanical agitation, or by chemical processes. Unstable emulsions will separate with time or temperature. Stable emulsions will not separate.
Flash Point: Is a measure of a fuel's flammability. More specifically, Flashpoint is the temperature where enough vapor is produced to create a flammable mixture. Fuels with higher Flashpoints are less flammable. Biodiesel is known to have a very high flash point. According to ASTM limits Biodiesel must have a flash point minimum of 130 C (266 F), while Diesel (D2) is required to have a Flashpoint above 52 C (125 F).
Free Fatty Acids (FFA): Fatty acids not attached to alcohol molecules like glycerin in vegetable oil or methanol in biodiesel. In the single stage base method of making biodiesel, FFAs are converted to soap. In an acid esterfication stage the FFA is converted directly to biodiesel.
Glycerin: A primary component of soap and has many uses in industry.
Isopropyl Alcohol: Also known as isopropanol, 2-Propanol and propan-2-ol. It is the main ingredient in rubbing alcohol and is used in titrating WVO. It is also used as a dewatering additive for gasoline.
KOH: Potassium Hydroxide also known as Caustic Potash. Used to make biodiesel from methanol, KOH (Methoxide) and vegetable oil.
Lye: NaOH also known as Sodium Hydroxide also known as Caustic Soda. A common chemical used in many industries.
Methanol: Methyl Alcohol - CH3OH – A common chemical used in many industries. Good solvent and a component of gasohol. Burned in top fuel eliminator dragsters, toy airplane engines and race go-carts. Lethal if consumed (see MSDS Sheets from Supplier). Used to make methoxide in biodiesel production. Methanol absorbs water from the air, so keep the container closed tightly.
Methoxide: Sodium Methoxide when made with Lye or also known as Potassium Methoxide when made with KOH. An organic salt, in its pure form a white powder. In biodiesel production, "methoxide" is a product of mixing methanol and sodium hydroxide or potassium hydroxide, yielding a solution of sodium methoxide or potassium methoxide in methanol, and a significant amount of heat. Sodium Methoxide or Potassium Methoxide in methanol is a liquid that will cause burns with contact with skin. Rinse with Vinegar thoroughly then with water and seek medical attention immediately. Highly explosive. Making sodium methoxide or potassium hydroxide is the most dangerous step when making biodiesel. Carefully consider the safety of the design of your equipment and workspace before producing, and wear protective clothing and a respirator when handling. Use immediately as methoxide loses reactive properties with time.
Mist Wash: A method of removing water-soluble impurities by spraying a fine mist of water over the top of biodiesel. As the small droplets of water fall into and through the biodiesel they attract any water-soluble impurities and collect on the bottom of the tank.
NaOH: Sodium Hydroxide, lye, caustic soda (Red Devil Drain Cleaner). A metallic base. Strongly alkaline and extremely corrosive. Mixing with fluids usually causes heat, and can create enough heat to ignite flammables (such as methanol), so add slowly. For biodiesel, this is one of the main reactants. Make sure you are purchasing "anhydrous sodium hydroxide." Anhydrous means it's dry, and water turns biodiesel into soap. Store this product in an airtight container to prevent NaOH from absorbing water and CO2 from the air. Store separately.
PH: A measure of acidity and alkalinity of a solution on a scale with 7 representing neutrality. Lower numbers indicate increasing acidity, and higher numbers increasing alkalinity. Each unit of change represents a tenfold change in acidity or alkalinity. pH is mathematically found by taking the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity. The units are gram equivalents per liter of the solution.
Processor (also see reactor): The vessel used to hold the WVO, methanol and catalyst while it chemically reacts and changes WVO into biodiesel.
Reactor (also see processor): The vessel used to contain the reaction converting WVO into biodiesel.
SVO: The abbreviation for Straight Vegetable Oil. Not recommended to run in diesel engines. SVO over time will polymerize the metal surfaces in a diesel engine resulting in an eventual catastrophic engine failure. SVO will not start engine, and will coke in the injectors as a hot engine cools. Many unknowingly or mulishly call SVO, biodiesel.
Titration: Applied to biodiesel, titration is the act of determining the acidity of a sample of WVO by the addition of a known base to the sample while testing with pH solution for the desired neutral pH=7 reading. The amount of base needed to neutralize an amount of WVO determines how much base to add to the entire batch.
Transesterfication: Process of creating esters from vegetable oil and sodium methoxide or potassium methoxide. Products are Crude Glycerin and Biodiesel if done properly.
Viscosity: How a liquid is resistant to flow; "thickness" or "thinness". In relationship to making Biodiesel, Methanol has a low viscosity, while vegetable oil has a high viscosity.
WVO: Waste Vegetable Oil. WVO is the usual feedstock for the making of biodiesel. WVO is collected from restaurants and other institutions that fry food products.