Becky Schapiro, 14, of Cleveland, Ohio, for her question:
WHEN WERE DETERGENTS DEVELOPED?
A detergent is a substance that cleans soiled surfaces. Soap is a type of detergent. But the word "detergent" usually refers only to synthetic detergents, which have a different chemical makeup than soap.
A German scientist named Fritz Gunther gets the credit for developing the first synthetic surfactant for use in detergents in 1916. Industries used his product, but it was too harsh for household use.
In 1933, the first household detergents based on synthetic surfactants were introduced in the United States, but the shortage of fats and other chemical raw materials during World War II slowed the further development of such products.
After the war, several soap companies began to produce detergents based on synthetic surfactants. Since then, the chemical industry has developed a variety of detergents for almost every cleaning job.
Before 1965, detergents in sewage sometimes caused surface foam on rivers and streams. Most detergents contained a synthetic surfactant called alkylbenzene sulfonate (ABS), which did not break down completely in sewage treatment systems.
In 1965, after more than 10 years of research, a detergent surfactant was developed in the industry called linear alkylbenzene sulfonate (LAS). Bacteria quickly break down LAS molecules and so detergents using it do not cause foam.
In the early 1970s, scientists noticed that chemicals called phosphates, which were used as detergent builders, contributed to water pollution. When phosphates and other chemicals enter rivers and lakes, they overfertilize simple water plants called algae.
Over fertilization increases the growth of these plants, which causes the oxygen supply in the water to be used up. Fish cannot live in such water, and so they die. Their bodies pollute the rivers and lakes, which also become choked by the algae. So phosphates have been banned.
After a number of state and local governments banned the sale of detergents that contained phosphates, manufactuers developed several phosphate substitutes.
People in the United States use an average of almost 31 pounds of detergents and soaps each year. These products are manufacturered in bars, flakes, grains, liquids and tablets.
Detergents are used to wash dishes and laundry, to scrub floors, to clean walls and windows and to do many other household jobs.
Industry uses detergents as cleaners, lubricants, softeners and polishers.
Detergents clean soiled material in much the same way as do soaps. The cleaning process consists of wetting the soiled material thoroughly, removing particles of dirt from the soiled material and suspending or holding the dirt particles in the water until they are rinsed away.