Shampoos, detergents, cleaning lotions and dishwashing liquids have one thing in common: they clean. But how does that actually work? Why does the grass stain disappear from the white T-shirt when you put some detergent in the washing machine? Why does hair still look greasy after washing if you forget the shampoo in the shower? The answer lies in an ingredient that is common to all detergents and soaps: surfactants. Surfactants are wash-active chemical substances that facilitate the removal of dirt in water.
Surfactants: production and classification
The probably oldest surfactants are soaps. These were already used by the ancient Egyptians and Germanic tribes for cleaning. Thanks to research in chemistry, today there are a wide variety of highly developed surfactants that are tailored to individual areas of application.
They are divided into non-ionic, anionic, cationic and amphoteric surfactants.
- Anionic surfactants have the highest washing power and are therefore primarily used for shampoos or detergents.
- Cationic surfactants are found in hair conditioners, fabric softeners or preservatives.
- Amphoteric surfactants support the action of other surfactants and are thus often used as co-surfactants.
- Non-ionic surfactants are particularly well tolerated by humans and are therefore used for facial cleansing lotions, disinfectants or emulsions.
Natural and synthetic surfactants
It is also possible to distinguish between natural as well as synthetic surfactants. Natural surfactants are those that are made from natural raw materials such as animal and vegetable fats or sugar.
Synthetic surfactants, on the other hand, are based on synthetic raw materials such as benzene, olefins or ethylene oxide.
Surfactants: mode of action
Basically, all surfactants have the same effect: if they are dissolved in water, they can reduce its surface tension. They make the water “softer,” so to speak. Similar to emulsifiers, each molecule of a surfactant has a water-friendly end and an end that is not soluble in water. During the washing process, the insoluble end of the molecule penetrates textile fibers and dirt particles.
The movement during washing, such as the spin cycle in the washing machine or the head massage when using shampoo, first detaches the dirt particles, then breaks them up and dissolves them in the water. In this way, the stains come out of the laundry, grease as well as dust from the hair and the oil from the stove.
Surfactants: environmental impact and compatibility.
Surfactants are pure chemistry and therefore poison for the environment. However, some surfactants are more degradable than others. In Germany, however, a legal regulation on the biodegradability of surfactants has been in force since 1977. This requires a minimum degradability of 80 percent for each type of surfactant.
Some surfactants are poorly tolerated by humans. Particularly in high concentrations, they can irritate mucous membranes, dry out the skin and trigger allergies. So when washing clothes, cleaning and in the bathroom, the rule is: less is more. Organic detergents on a purely vegetable basis are even better.
