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Fabric Stain Removal Guide

Detergent Classification

There are four main classes of detergents, anionic, cationic, nonionic, amphoteric.

Anionic Detergents

Anionic means a negatively charged molecule. In the early days I always remembered this by anionic (a negative). The detergency of the anionic detergent is vested in the anion. The anion is neutralised with an alkaline or basic material, to produce full detergency.

Cationic Detergents

Cation means positively charged. The detergency is in the cation, which can be a substantially sized molecule. Strong acids are used, such as Hydrochloric Acid to produce the Cl anion as the “neutralising” agent, although in essence, no neutralisation takes place in the manufacturing process.

nonionic Detergents

As the name implies, no ionic constituents are present. They are “ionically” inert.

Amphoteric Detergents

These contain both acidic and basic groups in their molecule, and can act as cationic or anionic detergents, depending on the pH of the solution, or as both cation and anion.

Anionic Detergents

Dealing with the common anionic detergents, we can place these detergents into the following main groupings:

Alkyl Aryl Sulphonates

Linear alkyl benzene sulphonate would be the highest quantity used of any detergent in the world, and the alkyl aryl sulphonates as a group would represent more than 40% of all detergent used.

They are cheap to manufacture, very efficient, and the petroleum industry is a starting point for the base raw material. The most important alkyl aryl condensate is DDB (dodecyl benzene). DDB is sulphonated to DDBSA (dodecyl benzene sulphonic acid), and this in turn is used as a detergent base, where it is neutralised with a base, such as sodium hydroxide, monoethanolamine, triethanolamine, potassium hydroxide, etc.

Long Chain (Fatty) Alcohol Sulphates

Made from fatty alcohol’s, and sulphated, these are used extensively in laundry detergents. They can be produced with varying carbon chain lengths, but a C12 - C18 alcohol sulphate is a good choice.

Other groups

Are the olefine sulphates and sulphonates, alpha olefine sulphates and sulphonates, sulphated monoglycerides, sulphated ethers, sulphosuccinates, alkane sulphonates, phosphate esters, alkyl isethionates, sucrose esters.

The anionic detergents are used extensively in most detergent systems, such as dishwash liquids, laundry liquid detergents, laundry powdered detergents, car wash detergents, shampoo’s etc.

Cationic Detergents

These have poor detergency, and are used more for germicides, fabric softeners, and specialist emulsifiers.

You cannot mix cationic and anionic detergents together, as it causes precipitation. However, Witco Chemical Corporation does produce a product - Emcol CC-36 - which can be mixed with an anionic, and these are powerful anti-static products.

The cationic detergents invariably contain amino compounds. The most widely used would be the quaternary ammonium salts, such as cetyl trimethylammonium chloride, a well known germicide.

nonionic Detergents

The vast majority of all nonionic detergents are condensation products or ethylene oxide with a hydrophobe. This group of detergents is enormous, and the permutations endless. They would be the single biggest group of all detergents, and I do not propose going into the endless chemistry of these products.

Amphoterics

These have the characteristics of both anionic detergents and cationic fabric softeners. They tend to work best at neutral pH, and are found in shampoo’s, skin cleaners and carpet shampoo. They are very stable in strong acidic conditions and have found favour for use with hydrofluoric acid.

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