THE HISTORY OF CLEANING PRODUCTS

The origins of personal cleanliness go back into prehistoric times.  Since water is essential for life, the earliest prehistoric people must have lived near water and thus must have known something about its cleaning properties, even if only for rinsing mud off their hands.  Early evidence of a soap-like material in recorded history was found in clay cylinders (dated about 2800 B.C.), during excavation of ancient Babylon.  Inscriptions say the inhabitant’s boiled fats with ashes, but do not say what the “soap” was used for.  Such materials were later used as a pomade or hairdressing.

Soap got its name, according to ancient Roman legend, from Mount Sapo, where animals were sacrificed.  Rain washed a mixture of melted animal tallow and ashes down into the clay along the edge of the Tiber River.  Women found that applying this clay mixture to their laundry made their wash cleaner with much less effort.  The ancient Germans and Gauls also are credited with discovering a substance called soap, made of goat’s tallow and ashes.  As Roman civilization advanced, so did bathing.  The first Roman baths, with water from their aqueducts, was built about 313 B.C.  The Baths became centers of luxurious, often decadent living.  By the second century A.D., the physician, Galen, recommend soap for both medicinal and washing purposes.  After the fall of Rome and the decline of bathing habits, Europe felt the impact of filth upon public health.  This lack of personal cleanliness and associated unsanitary living conditions contributed heavily to the great plaques of the Middle Ages, and especially to the Black Death of the 14^th century. 

French chemist, Nicolas Leblanc, provided a major step toward large-scale commercial soap making.  His process (patented in 1791) used common salt to produce soda ash (sodium carbonate), the active ingredient in ashes that combines with fat to form soap.  The process provided quantities of good, inexpensive soda.  In the mid-1800s the Belgian chemist, Ernest Solvay, invented the ammonia process, which also used common salt to make soda.  Solvay’s process further reduced the cost of soda and increased both the quality and quantity of soda available for manufacturing soap.

However, the breakthrough in soap technology came in 1811. The French chemist, Michel Eugene Chevreul, discovered that soap contained several different fatty acids. His studies of these fatty acids and of glycerin established the scientific basis for both fat and soap chemistry. Further study indicated that the fat molecules used for soapmaking were actually triglycerides: one molecule of glycerin chemically combined with three molecules of fatty acids, so named because they were found in fat. Each fat has its own distinctive combination of three fatty acid molecules with the glycerin molecule. The process of converting fats into soap by treating them with an alkali is called saponification (soapmaking). In one method of soapmaking, this may be done directly by boiling fat and alkali under controlled conditions. The fat and alkali react to form soap and glycerin.

Now, for a closer look at soap. The carboxylate end of the soap molecule is attracted by water. This is the water-loving (hydrophilic) end. Mean while the hydrocarbon chain is both repelled by water and simultaneously attracted to oil and grease in dirt. This is the water-hating (hydrophobic) end. To understand how soap works, let's assume that we have oily, greasy dirt on clothing. Water alone will not remove this dirt. One important reason for this is that the oil and grease in the dirt repel the water molecules. Now, let's add soap. The soap's water-hating portion is repelled by water but attracted to oil in dirt. Meanwhile, the water-loving portion is attracted to the water molecules. These opposing forces loosen the dirt and suspend it in water. Washing machine agitation and hand rubbing help pull the dirt free. Basically, soapmaking consists of several steps: selecting the fat or oil to be used, processing to produce the soap, removing the

by-products, and then formulating and finally processing the soap to produce the finished products that we use.  The fats and oils selected determine the quality and performance of a soap product. Virtually every animal fat and vegetable oil source has been used to make soap. Incidentally, fats and oils have basically the same molecular structure. Generally fats are solids, while oils are liquids at room temperature.

Although soap is a good cleaning agent, its effectiveness can be reduced when used in hard water. Mineral salts, mostly those of calcium (Ca) and magnesium (Mg), but sometimes iron (Fe) and manganese (Mn), cause the "hardness" in hard water and react with soap to form an insoluble curd known as a precipitate.  In contrast, detergents have excellent resistance to hard water minerals. Technically, any cleansing agent is a detergent.  However, in popular usage, washing and cleaning agents with a composition other than soap but clean by the same mechanisms as soap are called detergents. The first detergents were developed in Germany during World War I because of a shortage of fats and oils for making soap.

Household detergent production in the United States started in the early 1930s, but it was not until after World War II that their use soared. The wartime shortage of fats and oils spurred further development of detergents, as did the Navy's need for a cleaning agent that would work in the mineral-rich hard seawater. The most widely used replacement for fats and oils today is crude oil, which contains hydrocarbons. Scientists working on detergent development found that these hydrocarbons could be used for the hydrocarbon end of a new soap-like material. This hydrocarbon end is repelled by water but attracted to oil in dirt. Also needed was a substitute for the water-seeking end of the soap-like molecule: one that would not form curds and that would work in hard water  Scientists found that a sulfuric acid molecule reacts with a hydrocarbon from petroleum. This reaction produces a new acid similar to a fatty acid. A second reaction adds an alkali to the acid to produce what is known as a detergent's surfactant (surface active) molecule. These surfactants are less sensitive than soap to the hardness minerals in water, and most detergent surfactants will not form an insoluble residue.

The breakthroughs in the development of household detergents come in 1946: the first built detergent (containing a surfactant phosphate builder combination) was introduced in the United States. Phosphate builders vastly improved detergent performance, making them suitable for heavy duty cleaning. By 1953, sales of detergents had surpassed that of soap in the United States. Now detergents have largely replaced soap-based products for laundering and home care.  Soap and detergent surfactant molecules work in similar ways to loosen dirt. Substantial numbers of these molecules team up in an effective group to form a micelle. With their bodies anchored in oily dirt, they loosen, surround, and in effect suspend the dirt until it can be rinsed away.

Increased detergent use in the early 1950s coincided with some widely publicized foaming incidents even though foaming on rivers and streams existed long before detergents were introduced. Detergent foaming was an aesthetic problem.  It did not pose a threat to humans or fish nor did it contribute to taste or odor problems.  Phosphates become a basic builder in heavy-duty laundry detergents because of their effectiveness, reasonable cost, and safety for use with appliances, fabrics, and humans.  In fact, phosphates are essential to all living things. This is the basis of the problem: 

phosphates nourish plant growth in lakes and streams. Lakes age naturally, becoming filled with plants and silt, forming marshes and finally, solid land. This aging process normally takes thousands of years, but man's activities greatly speed up the process. This is known as cultural eutrophication. In an effort to reduce cultural eutrophication, many detergent manufactures have reduced the phosphate content in laundry detergents through reformulation. Many scientists and engineers advocate adequate municipal wastewater treatment: removing nutrients, including phosphates. Such treatment plants can remove phosphates at a cost 5 to 10 times less than it cost consumers to use phosphate-free products.