Surfactants in Laundry Detergents
A surfactant is the working molecule in a detergent mixture, or in a soap. In general surfactant molecules are long carbon chain molecules which attract water molecules, on the one end, and yet repel water molecules on the other end. There are numerous possibilities in how the surfactant molecule may be formed chemically. And, the chemical structure of surfactants will influence the manner in which that surfactant can interact with water, with minerals in the water and with the oil and dirt on the laundry. Later in this series there will be a description of how a surfactant in a laundry detergent actually works to clean the laundry but for now we will just look at the types of surfactants that may be used in the detergent and cleaning business.
Industry is always on the search for a more effective, cheaper alternative to current surfactants that are in use. At the level of laundry itself, there are several specific types of surfactants that are used. These chemical compounds are used for particular purposes. There are four main classes of surfactants used in laundry detergents. These are:
- Anionic Surfactants
- Cationic Surfactants
- Non-ionic Surfactants
- Amphoteric/Zwetterinic Surfactants
These classes of surfactant are defined according to the type of charge that the water loving head of the surfactant molecule carries. Anionic surfactants ( the most commonly used surfactants) have negatively charged water loving heads, cationic surfactants have positively charged heads, nonionic surfactants have only an electrical tendency to their water loving heads, not a full charge. Amphoteric Surfactants polar heads slip from positively charged to negatively charged depending upon the conditions.
There are many possible formations of the long carbon chain that will be attached to the water loving head of any of these types of surfactants. The nature of the carbon chain in the surfactant can have a big influence upon how well it performs its laundry functions (not all or which are cleaning) and, perhaps more importantly, what happens to the surfactant when it enters the home or the environment.