Detergent
Detergent is a compound, or a mixture of compounds, intended to assist cleaning. The term is often used to differentiate between soap and other chemical surfactants used for cleaning purposes.
Composition
Detergents, especially those made for use with water, often include different components such as:
- Surfactants to 'cut' grease and to wet surfaces
- Abrasive to scour
- Substances to modify pH or to affect performance or stability of other ingredients, acids for descaling or caustics to destroy dirt
- Water softeners to counteract the effect of "hardness" ions on other ingredients
- oxidants (oxidizers) for bleaching and destruction of dirt
- Non-surfactant materials that keep dirt in suspension
- Enzymes to digest proteins, fats, or carbohydrates in dirt or to modify fabric feel
- Ingredients that modify the foaming properties of the cleaning surfactants, to either stabilize or counteract foam
- Ingredients that affect the aesthetic properties, such as optical brighteners, fabric softeners, colors, perfumes, etc.
- Washing agents may contain soap for the purpose of reducing foam rather than cleaning fabric.
Detergent Choice
There are several factors which dictate what compositions of detergent should be used—namely the material to be cleaned, the apparatus to be used and tolerance for dirt. For instance, all of the following are used to clean glass. The sheer range of different detergents which can be used demonstrates the importance of context in the selection of an appropriate glass-cleaning agent.
- A chromic acid solution is used to get glass very clean for certain precision-demanding purposes, namely in analytical chemistry,
- A high foaming mixture of surfactants with low skin irritation—for hand washing of drink glasses in a sink or dishpan,
- Any of various non-foaming compositions—for glasses in a dishwashing machine,
- An ammonia-containing solution—for cleaning windows with no rinsing,
- Ethanol or methanol in Windshield washer fluid is used for a vehicle in motion
Terminology
Sometimes the word "detergent" is used in distinction to "soap". For a while during the infancy of other surfactants as commercial detergent products, the term "syndet", short for "synthetic detergent" was promoted to indicate this, but never caught on very well, and is incorrect in any event because soap is itself synthesized via saponification of glycerides. The term "soapless soap" also saw a brief vogue. Unfortunately, there is no accurate term for detergents not made of soap other than "soapless detergent" or "non-soap detergent".
Also, the term "detergent" is sometimes used for surfactants in general, even when they are not used for cleaning. As can be seen above, this too is terminology that should be avoided as long as the term "surfactant" itself is available.
Technically, plain water, if used for cleaning, is a detergent. Probably the most widely used detergents other than water are soaps or mixtures composed chiefly of soaps. However, not all soaps have significant detergency. Often the word "soap" is used to indicate any detergent, especially those that have characteristics similar to those of soap.
Ecological impact of use
While effort has been made to reduce their negative effect upon the environment, the results have been mixed.
See also
http://chemistry.about.com/od/howthingswork/f/detergentfaq.htm
Sources
- Much of the information of this page was derived from: Detergents guide