Saturday, July 13, 2013

Detergents




Detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions". Commonly, "detergent" refers to alkylbenzenesulfonate, a family of compounds that are similar to soap but are more soluble in hard water, because the polar sulfonate (inorganic, hydrophilic) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water.


Detergent acts as a cleansing agent. In that sense soap is also a detergent. But the word detergent usually refers to a water-soluble cleansing agent that combines with impurities and dirt to make them more soluble and differs from soap in not forming a scum with the salts in hard water. The surfactants used for detergents are less sensitive than soap to the hardness minerals in water and most will not form a film. The mineral salts react with soap to form an insoluble precipitate known as soap film or scum. Soap film does not rinse away easily. It tends to remain behind and produces visible deposits on clothing and makes fabrics feel stiff (hard). It also attaches to the insides of bathtubs, sinks and washing machines. This reduces the amount of soap available for cleaning.
The surfactants used in detergents can be engineered to perform well under a variety of conditions. A detergent contains an active agent called surfactant that wets the fabric, emulsifies oily matter, solubilizes grime and keeps the soil in suspension. Detergent surfactants are made from a variety of petrochemicals (derived from petroleum) and/or oleochemicals (derived from fats and oils).

A good detergent should have the following properties. It should be:
1.      able to soften water completely
2.      completely soluble in water
3.      non-corrosive to surfaces (metals and buildings)
4.      non-toxic and biodegradable
5.      economical in use
It should have:
6.      good wetting or penetrating ability
7.      emulsifying ability on fat
8.      dissolving ability on food solids
9.      deflocculating, dispersing or suspending ability
10.  good rinsing properties
11.  scale and rust removing properties

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