Laundry detergent, or washing powder, is a substance which is a type of detergent that is added when one is washing laundry to help get the laundry cleaner. Laundry detergent has traditionally been a powdered or granular solid, but the use of liquid laundry detergents has gradually increased over the years, and the popularity of liquid detergent now rivals that of solid detergent. Some brands also manufacture laundry soap in tablets and dissolvable packets, so as to eliminate the need to measure soap for each load of laundry. In some countries where washing clothes by hand is more popular, detergent bars are more popular. Recently, environmentally friendly detergents have enjoyed a surge in popularity.

Detergent molecules are long and the detergents can mold into different forms of matter so they can be asymmetrical: one end attracts long pieces of dirt while the other end attracts water, which is how detergent lifts dirt from wet clothes. A key ingredient in both solid and liquid laundry detergents is a surfactant. A surfactant is a substance which, when added to water, significantly reduces the surface tension of the water, enabling water to wash surfaces better. There are many different types of organic compounds which can function as surfactants. Many surfactants are thick, viscous liquids; however, some are soft, waxy or greasy solids. Soap nuts are a natural laundry detergent that grow on sapindus trees, which contain a surfactant called saponin. These saponins reduce the surface tension of water, thus giving a chemical free laundry detergent which has been used for centuries in countries such as India and Nepal. Soap nuts are now becoming more popular in North America & can be purchased in many online stores if you Google soap nuts.

Surfactants typically have somewhat longer molecules which may or may not have an electric charge. Surfactants with uncharged molecules are non-ionic surfactants. Surfactants with positively charged molecules (or ions) are cationic surfactants. Surfactants with negatively charged molecules (or ions) are anionic surfactants. Surfactants with both positively and negatively charged part in the same molecule are zwitterionic surfactants. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have been used in laundry detergents. The use of cationic and anionic surfactants together is incompatible in the same detergent. The usual content of surfactants in a typical detergent is about 8-18%.

Laundry detergents may have ingredients to help control the pH of the wash water. For example, solid detergents usually contain sodium carbonate (soda ash) or sodium bicarbonate to maintain pH by neutralizing any acidic materials that may enter the wash water.

In the 1960s, detergent manufacturers waged an advertising battle over who had the longest lasting suds, and detergent compounds quickly appeared in the waterways. Suds began to appear in streams, rivers, lakes, and at the foot of Niagara Falls, where piles of discolored detergent foam rose eight feet high.

Detergents also contain phosphate additives to soften the water and thereby improve the effectiveness of the detergent molecules. It was noted that between 1940 and 1970 the amount of phosphates in city wastewater increased from 20,000 to 150,000 tons per year.

With the increase in phosphates, algal blooms grew splendidly on the excess phosphorus and consumed most of the oxygen in the waters, killing fish and plants.

As part of the switch to go green and protect the environment, by 2008, almost all liquid laundry detergent will be sold in small bottles and in concentrated form, which supposedly helps protect the environment by introducing less plastic into it. Some stores around the US are already carrying concentrated laundry detergent while some in the Northeast and Midwest States are only carrying the small bottles that are used for High Efficiency Washers.

Soap nuts are a natural alternative to laundry detergent that have been used in India and Nepal for centuries. They are actually not nuts at all, but a fruit of the sapindus tree. With no added chemicals or preservatives, soap nuts are one of the best environmentally friendly alternatives to commercial laundry detergents. They can be purchased in many online stores.

Source: Wikipedia (All text is available under the terms of the Creative Commons Attribution-ShareAlike License)