Nepedia
Back to Discover
Advanced Reader
💻

Detergent

technology Maturity 5-7 Next article →

A detergent is a cleaning product containing surfactants and other specialized components.

Diskflaskor
Diskflaskor

While people often use the word to mean soap, detergents are usually synthetic compounds. In a scientific sense, a detergent is any surfactant or mixture of surfactants that cleans in dilute solutions. The primary goal of detergency is to remove unwanted substances, known as soils, from a substrate like fabric.

Micelle scheme-en
Micelle scheme-en

Detergents are complex mixtures. They often include water to help application and builders to soften water. They may also contain enzymes to break down proteins, fats, or starches. Fragrances and dyes are frequently added to improve the user's sensory experience.

The most important part of a detergent is the surfactant. Surfactants are molecules with an amphiphilic structure. This means they have two distinct parts. One part is a hydrophilic head, which is polar and attracted to water. The other part is a hydrophobic tail, which is non-polar and avoids water. These tails can be straight or branched hydrocarbons.

Micelle scheme-en
Micelle scheme-en

Because they have these two sides, surfactants can decrease the surface tension of water. This allows water to mix with hydrophobic substances like grease or oil. This dual nature is what makes cleaning possible.

Surfactants work by forming structures called micelles.

Micelle scheme-en
Micelle scheme-en

When surfactant molecules aggregate, they create a tiny sphere. The hydrophobic tails move toward the center to form a core. This core hides from the water. The hydrophilic heads stay on the outside to face the water. These micelles can trap and remove grease, protein, or other soiling particles. The concentration where these micelles begin to form is called the critical micelle concentration (CMC). There is also a cloud point, which is the temperature where micelles aggregate further and the solution becomes cloudy.

Chemists classify surfactants into four main groups based on their electrical charge. Anionic surfactants are the most common type. An estimated 6 billion kilograms of anionic surfactants are produced every year for domestic markets.

Soap&Detergents
Soap&Detergents

A common example is alkylbenzene sulfonates. These are more soluble in hard water than soap is. This is because the sulfonate group is less likely to bind to calcium or magnesium ions. Cationic surfactants have a positive charge and use quaternary ammonium groups. They generally have poor detergency. Non-ionic surfactants have uncharged heads and do not foam much. Finally, amphoteric surfactants have a net zero charge within certain pH ranges.

The history of cleaning shows a long evolution of technology. Humans have used soap as a surfactant since the Sumerian era in 2500 B.C. In the 1860s, sodium silicate was used in American soap-making. In 1876, Henkel sold a sodium silicate product in Germany. By 1907, Henkel launched Persil, the first self-acting laundry detergent. This used sodium perborate as a bleaching agent. During the First World War, a shortage of fats led chemists to create synthetic detergents from coal tar. These early versions were not very effective. It was not until the 1930s that effective fatty alcohol sulphates became available for large-scale production.

Major improvements occurred in the 1940s with the development of "built" detergents. These included phosphate builders to soften water. Builders work through chelation, which manages calcium and magnesium ions. This helps maintain an alkaline pH and keeps soils in solution. After the Second World War, the petrochemical industry provided more materials for synthetic surfactants. Alkylbenzene sulfonates became the most important type during this time. However, the use of phosphates caused nutrient pollution concerns. This led to the development of newer alternatives like zeolite A and NTA. Scientists also moved toward more biodegradable surfactants, such as linear alkylbenzene sulfonates.

Detergents have many important applications beyond the laundry room.

Laundry detergent pods
Laundry detergent pods

They are used in dishwashing liquids, shampoos, and toothpastes. In the automotive industry, detergents are added to fuels at concentrations of about 300 ppm. These help prevent fouling in fuel injectors and carburetors. In science, reagent-grade detergents are used to isolate membrane proteins in cells. They can disrupt cell membranes to help scientists study ion channels and receptors. From cleaning clothes to powering engines, detergents are essential to modern life.

Laundry detergent pods
Laundry detergent pods
676 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (4)
File:Diskflaskor.JPG
Diskflaskor.JPG
File:Micelle scheme-en.svg
Micelle scheme-en.svg
File:Soap&Detergents.png
Soap&Detergents.png
File:Laundry detergent pods.jpg
Laundry detergent pods.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.