Glossary

Acid
a classification of substances that liberate hydrogen ions in water, and are normally sour and corrosive, with a pH lower than 7. A compound or atom that donates protons.

Alcohol
a large classification of organic compounds containing one or more hydroxyl groups attached to carbon atoms.

Aliphatic
any non-aromatic organic compound having an open chain structure.

Alkali
a classification of substances that liberate hydroxide ions in water, to form caustic and corrosive solutions which turn litmus paper blue, with a pH higher than 7, for example sodium Hydroxide. A compound that reacts with or neutralizes hydrogen ions.

Anhyrdous
without water, dry. Liquids and solids (powders) are sold as "anhydrous" when they have been processed to remove water from the end product. Transesterification of biodiesel must be an anhydrous process or funny things hapen. Water in the vegetable oil causes either no reaction or cloudy biodiesel, and water in lye or methanol renders it less useful or even useless, depending on how much water is present. Either let your vegetable oil settle for 2-3 days before using and drain the water off the bottom, or heat the oil and boil off the water. Store lye and methanol in (separate) air-tight containers.

Aromatic
any organic compound containing de-localised electrons in a ring structure - e.g. benzene, benzoic acid.

ASTM
American Society for Testing and Materials - an international voluntary standards organization that develops and produces technical standards for materials, products, systems and services.

Base
a classification of substances which when combined with an acid will form a salt plus water, usually producing hydroxide ions when dissolved.

Bubble Wash
A method of final washing of biodiesel through air agitation. Biodiesel floats above a quantity of water. Bubbles from an aquarium air pump and air stone 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. Simple diffusion causes water soluble impurities in the biodiesel to be extracted into the water. As the bubble reaches the surface and breaks, the water is freed and percolates back down through the biodiesel again.

Carbon chain
the atomic structure of hydrocarbons in which a series of carbon atoms, saturated by hydrogen atoms, form a chain. Volatile oils have shorter chains. Fats have longer chain lengths, and waxes have extremely long chains.

Carboxyl
Carboxylic - the uni-valent acid radical (-COOH), present in most organic acids, this making them bio-degradable.

Catalyst
a substance which without itself undergoing any permanent chemical change, facilitates or enables a reaction between other substances.

Cetane Number
Measure of fuel ignition characteristics. Like the octane number used for gasoline, the higher the value, the better the fuel performance. A higher cetane number correlates with improved combustion, improved cold starting, reduced noise, white smoke, HC, CO and particulate emissions particularly during early warm-up phase. The EPA uses this parameter as a measure of aromatic content in fuel. Typical Cetane numbers around the world are as follows: Europe: 43 - 57, average 50 U.S. lower, minimum 40, average 43.

Cloud point
The temperature at which the first wax crystals appear and a standardized ASTM test protocol is used to determine this temperature.

Colloid
A stable system of small particles dispersed in something else. A multi-phase system in which one dimension of a dispersed phase is of colloidal size. Colloids are the liquid and solid forms of aerosols, foams, emulsions, and suspensions within the colloidal size class. Milk and smoke are both colloids. Colloidal size is typically.001 micron to 1 micron in any dimension. Dispersions where the particle size is in this range are referred to as colloidal aerosols, colloidal emulsions, colloidal foams, or colloidal suspensions.

Emulsion
a usually unstable dispersion of two liquids which do not normally mix (they are immiscible). Emulsions can be formed either by mechanical aggitation, or by chemical processes. Unstable emulstions will separate over time or temperature, stable emulsions will not separate.

Ester
a classification of organic compounds occurring naturally as oils and fats, produced by replacing the hydrogen of an acid by an alkyl, aryl, radical. A compound of an organic acid bonded via an ester bond to an alcohol. Any of a large group of organic compounds formed when an acid and alcohol is mixed. CH3COOCH3 (Methyl acetate) is the simplest ester. Biodiesel is often described as a Fatty Acid Methyl Ester (FAME).

Ethanol
C2H6O or CH3-CH2-OH - An organic alcohol also called ethyl alcohol, formed when fermenting sugars or glycerin. Ethanol is also a great solvent.

FAME
Fatty Acid Methyl Ester, a commonly used chemical term for biodiesel.

Fat
a classification of natural esters of glycerol, and fatty acids existing as solids at room temperature.

Fatty Acid
a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated.

Flash Point
the lowest temperature at which it can form an ignitable mix with air.

Free Fatty Acids
fatty acid hydrocarbon chains detached from other molecules, like glycerol.

Hydrocarbon
a compound of hydrogen and carbon, often occurring as long atomic chains in which each carbon atom is attached to two hydrogen atoms forming a long chain. They store a great deal of energy.

Hydrogenation
a chemical reaction in which unsaturated bonds between carbon atoms are reduced by attachment of a hydrogen atom to each carbon. When the process is carried to completion it converts unsaturated fatty acids to saturated ones. Changing the degree of saturation of the fat changes important physical properties such as melting point, which is why the liquids become semi-solid. Since partially hydrogenated vegetable oils are much less expensive than most other fats with similar characteristicts, and because they have other desirable characteristics leading to longer shelf life, they are the predominant fat used in most commercial baked goods.

Hygroscopic
The tendency of something to absorb water (usually from humidity in the air). Biodiesel absorbs water to about 1200 parts per million (PPM). Methanol and NaOH are also hygroscopic. Keep containers closed.

Indicator
a substance which changes colour at a given stage in or as a result of a chemical reaction. Phenolphthalein is commonly used in titrations measuring the acidity of vegetable.

Iodine #
Standard natural oil assay to measure the degree of unsaturation (or the number of double bonds present) in vegetable oils and fats.

Kerosene
Dodecane (Kerosene) C12H26 commonly used mineral fuel oil used as aviation fuel and central heating consisting of many hydrocarbons containing molecules with about 10 to 16 carbon atoms.

Life-cycle analysis
a total valuation of a process, in which all the inputs and outcomes of a reaction are fully considered.

Lipid
a classification of organic compounds, including fatty acids, oils, waxes and steroids, that are insoluble in water but soluble in organic solvents. They consist of a polar head with one to three non polar tails. A triglyceride is a type of lipid, the glycerin being the head and the ester chains being the tails.

Methanol
CH3OH - A volatile colourless alcohol, derived originally as wood alcohol, used as a racing fuel and as a solvent. Also called methyl alcohol. Lethal if consumed. Used to make methoxide in biodiesel production. Methanol absorbs water from the air, so keep the container closed tightly, and purchase methanol which is known to be dry (anhydrous) or is 99.9% pure.

Methoxide
Na O-CH3 Sodium Methoxide - Sodium Methylate. An organic salt, in pure form a white powder. In biodiesel production, "methoxide" is a product of mixing methanol and sodium hydroxide, yielding a solution of sodium methoxide in methanol, and a significant amount of heat. Sodium Methoxide in methanol is a liquid that kills nerve cells before you can feel the pain. Rinse with water and seek medical attention immediately. Also highly explosive. Making sodium methoxide 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.

Organic
compounds that contain carbon, which are often created as a result of a life process.

Oxidation
burning in oxygen, normally highly exothermic (heat releasing), but also any increase in oxidization state, (i.e. loss of electrons). Results in the formation of an oxide, rusting or corroding. Various materials, such as copper and brass, may oxidize in the presence of vegetable oil or biodiesel.

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.

Pour point
The temperature at which the fuel is no longer pumpable.

Rape Seed Oil
Food grade oil produced from rape seed is called Canola oil. Canola is a name taken from "Canada oil" due to the fact that much of the development of the oil was performed in Canada. Another early term for this oil is Colza. Makes good biodiesel.

Saponification
The reaction of an ester with a metallic base and water. The making of soap. This happens sometimes when you use too much lye in a biodiesel reaction... No worries - you can re-react the resulting top layer of unreacted liquid, and if you wish you can turn the semi-solid bottom layer into soap by adding more lye (make sure you know how much to add...).

Saturated
a fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain. Saturated fats tend to be solid at room temperature. Diets high in saturated fat correlate in some studies with an increased incidence of atherosclerosis and coronary heart disease.

Sodium Hydroxide
NaOH, 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.

Suspension
A dispersion of a solid in a gas, liquid, or solid

Tallow
One of the harder organic fats derived from animal carcasses, made by rendering the internal body fat found within the abdominal cavity under the backbone and surrounding the kidneys. This material was greatly used in manufacture of soap and candle wax.

Transesterification
The process of making biodiesel by the separation of the three hydrocarbon chains from a lipid triglyceride to form glycerol, and biodiesel. It is the process of exchanging the alkyl group of an ester by another alcohol. These reactions are often catalyzed by the addition of an acid or base. Acids can catalyse the reaction by donating an electron to the alkyl group, thus making it more reactive, while bases can catalyse the reaction by removing an electron from the alcohol, thus making it more reactive.

Triglyceride
natural fats and oils, composed of glycerin and three fatty acid chains.

ULSD
Ultra low Sulphur Diesel. A type of diesel fuel promote in recent years in an attempt to reduce atmospheric pollution but at the expense of engine wear.

Unsaturated
a fat or fatty acid containing double or occasionally triple bonds. Many vegetable oils contain fatty acids with one of more double bonds in them. Fat molecules are monounsaturated if each contains one double bond, and polyunsaturated if each contain more than one.

Viscosity
the ability of a fluid to respond to movement. A high viscosity will resist movement, and a low viscosity will flow quickly. This is not necessarily the same as density. Viscosity is normally measured comparatively by the time a given volume of liquid will pass through a pipe of fixed diameter. Methanol has a low viscosity, while vegetable oil has a high viscosity.

WVO
Waste Vegetable Oil. The oil we collect from restaurant grease traps etc, which is the main constituent of our fuel.