Detergent

Detergent- one of the most important helpers in our daily life.

Detergent is one of the most important daily products that we use to carry out laundry. We use detergent to clean our clothes because greasy stain and organic solid cannot be removed by pure water itself.

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It is a common myth that many believe that the more detergent they use, the cleaner their clothes will be. But that is not how a laundry detergent works. In fact, all laundry detergent leave a residue on clothing, which will be absorbed by our skin and cause certain ill effects like skin or eye irritation. As a result, being a wise consumer should be more alert in choosing the suitable detergent by understanding more about the components in detergent and how detergent actually works to perform such a clean and bright appearance for our clothing.

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 What is detergent?

Generally, detergent is known as a substance that helps removing the dirt or stain. It is an effective cleaning product due to the fact that it contains one or more surfactants. A surfactant is an organic chemical that tends to reduce the surface tension of a liquid in which it is dissolved. These surfactants are able to perform well under different types of conditions. Detergents are commonly found in powdered form or concentrated solutions. Detergents, similarly to soap, are amphiphilic: partially hydrophilic (soluble in water) and partially hydrophobic (soluble in oil). By having such dual nature, it facilitates the mixture of hydrophobic compounds (like grease and oil) with water. 

Structure of the anionic detergent sodium dodecyl sulfate (SDS), showing the hydrophilic and hydrophobic regions.

Chemical classification of detergents

Basically, detergents are classified into four main groups. There are anionic, cationic, non-ionic and amphoteric detergents. The classification depends on the electrical charge of the surfactants.

Anionic detergents

Anionic means a negatively charged molecule. These detergents are named so because a major part of their molecules are anion. Anionic part of molecule plays a role in cleansing action. Anionic surfactants are used in household cleaner and laundry. For instance, linear alkylbenzene sulfonates is a typical anionic surfactant used in detergent.

Cationic detergents

Cation means positively charged. The reason the detergents are cationic is because a large part of their molecule are cations and cationic part is involved in cleansing action. Cationic surfactants are often used in fabric softeners. For example, quaternary ammonium salts is one of the cationic surfactants used in detergent.

Nonionic detergents

As the name implies, these detergents do not contain any ions. They are “ionically” inert. Since they do not ionize in solution, they are resistant to water hardness. Nonionic surfactants are commonly used in laundry as well. For instance, alcohol ethoxylates are widely used.

Amphoteric detergents

Amphoteric detergents contain both acidic and basic groups in their molecule. Hence, they have the ability to be anionic and cationic in solution, depending on the acidic or alkalinity of water. But they tend to work best at neutral pH. The usage of this type of detergent is mainly for personal cleaning because of their stability and mildness. The major amphoterics are imidazolines and betaines.

Ingredients used in detergents and its functions

Ingredients	Functions	Examples of organic chemicals in the ingredients of detergents
1. Alkalis	- to increase alkalinity in order to get rid of acidic, fatty and oily soils. - make builders and surfactants more efficient	Ethanolamines - an organic chemical compound used in raw material of in the production of detergents
2. Antiredeposition agents	- to prevent soil from depositing after removal during washing	Carboxymethyl cellulose - one of the most versatile hydrocolloids used  - its various properties makes it useful in many industrial applications
3. Biological enzymes	- to break down fat and protein molecules in food stains	Lipase  - enzyme that catalyzes the hydrolysis of fats Protease - enzyme that carries out proteolysis
4. Bleach	- to help whiten and brighten - to remove stains	Tetraacetylethylenediamine - an organic chemical used as a peroxide bleach activator in household detergents
5. Hydrotropes	- to prevent liquids product from separating into layers	Ethyl alcohol - a colorless flammable liquid
6. Preservatives	- to protect against natural effects of product aging, e.g., decay, discoloration, oxidation and bacterial attack	Butylated hydroxytoluene - a lipophilic, organic compuond, chemically a derivative of phenol   - useful for antioxidant properties. Ethylenediamine   - an organic compound in colorless liquid with an ammonia-like odour
7. Solvents	- to carry out cleaning without leaving residues - to prevent separation or deterioration of ingredients in liquid products	Ethanol - a volatile, flammable, colorless liquid with a slight chemical odour - miscible with water - a good general purpose solvent Isopropanol - a colorless, flammable chemical compound with a strong odor - a structural isomer of propanol
8. Stabilizers	- to prevent the formation of foam which in excess that will affect the performance of automatic washing machines.	2-Butoxyethanol   - organic compound which has colorless liquid and a sweet, ether-like odor - derives from the family of glycol ethers and is a butyl ether of ethylene glycol - a relatively nonvolatile, inexpensive solvent of low toxicity

The cleansing action of detergent

Step 1: Action of detergent on dirt

When detergent is mixed with water, it lowers the surface tension of water and wets the dirty surface. The hydrophilic part (head) of detergent ion dissolve in water. The hydrophobic part (tail part) of detergent ions dissolve in the layer of grease.

Step 2: Dirt being surrounded by detergent ions

When water is agitated slightly, it helps to loosen the grease and lift the grease off the fabric surface.

Step 3: Lifting dirt from cloth

On further agitation during cleaning, the oily dirt is lifted up from the surface since the density of oil is less than water. 

Step 4: Emulsifying dirt in water

When water is shaken, the grease will be emulsified when it breaks into smaller droplets. These greasy droplets repel one another because they can carry the same charge. Therefore, the grease is suspended in the solution. When the cloth is rinsed with water, the droplets will be washed away and leaving the cloth clean.

References:

Websites

http://www.encyclopedia.com/topic/detergent.aspx

http://www.sigmaaldrich.com/technical-documents/articles/biofiles/detergent-properties.html

https://en.wikipedia.org/wiki/Detergent

http://www.cleaninginstitute.org/clean_living/soaps__detergents_chemistry.aspx

http://www.slideshare.net/apoorvjndl/soaps-and-detergents-42434087

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