Cleansing Action of Detergent

Explain the Cleaning Action of Detergent | Mechanism of Cleansing Action of Detergent

Cleansing Action of Detergent


Cleansing Action of Detergent

Cleansing action of detergents is due to their capacity to reduce the surface tension of water, emulsify oil or grease, and retain it in suspension in water.

Synthetic detergent have the same type of molecular structure as soap i.e. a tadpole like molecule having two parts. First part is a long chain hydrocarbon part (hydrophobic, insoluble in water but soluble in oil and grease) and second part is a short ionic part SO3Na or SO4Na (hydrophilic, soluble in water but insoluble in oil and grease). Thus the cleansing action is exactly similar to that of soaps whereby the formation of micelles followed by emulsification occurs. The only difference is that detergents work with hard water also.


When the detergent is added to dirty clothes having grease and oily substances, the greasy and oily dirt particles attach themselves to the hydrocarbon part and ionic part remains attached to the water. When the dirty clothes are agitated in a detergent solution, the dirt particles attached to the hydrocarbon part molecule get washed away in water and the clothes get cleaned.
Cleansing Action of Detergent

However synthetic detergents can lather well even in hard water because they are soluble in sodium or potassium salts of sulphonic acid or alkyl hydrogen sulphate and similarly form soluble calcium or magnesium salts on reacting with the calcium ions or magnesium ions present in water. This is a major advantage of the cleansing property of detergents over soap.


1. Why is detergent better than soap in cleansing action?

Detergents and soaps are both surfactants, which means they have a hydrophilic (water-loving) and a hydrophobic (water-hating) end. This allows them to dissolve both water and oil-based dirt and grime, and then rinse them away. However, detergents have several advantages over soaps that make them better for cleansing action.

Detergents are more effective at removing dirt and grime because they have a stronger hydrophilic end, which allows them to bind more tightly to water molecules. This means that they can more effectively dissolve and remove dirt and grime from surfaces.

Detergents are more effective in hard water. Soaps form insoluble salts with calcium and magnesium ions in hard water, which can make them less effective at cleaning. Detergents, on the other hand, do not form these salts, so they can be used effectively in hard water.


Detergents are more versatile and can be used to clean a wide variety of surfaces, including fabrics, dishes, and floors. Soaps, on the other hand, are not as effective on some surfaces, such as fabrics.

Detergents are less likely to irritate the skin. Soaps can be harsh on the skin, especially if they are used frequently. Detergents, on the other hand, are less likely to cause irritation.

In short we can say that detergents are a better choice than soaps for cleansing action because they are more effective at removing dirt and grime, more effective in hard water, more versatile, and less likely to irritate the skin.