Surfactants are one of the components used in making detergents to eliminate dirt from clothes, skin and household utensils mainly in bathrooms and kitchens and extensively used in industries. The word surfactant is derived from the word surface active agent.
Surfactants perform their function by separating the interface between oils or dirt and water. The oil and dirt is held in suspension acting in their removal. Surfactants act in this manner because they include hydrophilic group like an acid anion(SO3– or CO2–) and a hydrophobic group like alkyl chain. Water molecules tend to congregate close to the latter.
Soaps were the foremost surfactants and obtained from fats called glycerides since they are esters which are formed by trihydric alcohol, glycerol with fatty acids that have lengthy chain carboxylic acids. Glycerides are hydrolyzed by heating with a solution of sodium hydroxide to make soaps, sodium salts of acids and propane 1,2,3 triol and this process is called as saponification.
Action of Surfactants
- Surfactants consist of hydrophobic and hydrophilic portions.
- The molecules of surfactant are adsorbed on the oil surface and hence remove it from the oil surface.
- The molecules of surfactant surround the oil after it has been removed and prevents it from depositing again.
The glycerides which are used in making surfactants contain unsaturated and saturated carboxylic acids that consist of even number of carbon atoms in the range of 12-20 such as stearic acid, CH3(CH2)16CO2H.
Synthetic surfactants hold one major edge over soaps. Since soaps form insoluble magnesium and calcium salts with magnesium and calcium ions in hard water and clays that exists in the dirt where lot of soap goes in vain in making an insoluble scrum. However, this can be avoided by using a synthetic surfactant. For instance, in anionic surfactants, the carboxylate group is replaced by sulfonate as the hydrophilic component. The corresponding magnesium and calcium salts are soluble in water more than salts of carboxylic acids.
Uses of Surfactants
A vast range of surfactants like Emulsifiers, foaming agents and wetting agents are utilized based on the areas of use. Surfactants minimize the surface tension with respect to the phase and hence lie at the heart of interfacial chemistry. To know more applications of surfactants in daily life and manufacture processes in various industries, you can visit BYJU’S.