In the desert of Huang Chengcheng in the southwest of Cairo, the Egyptian capital, stands a pyramid tomb with a square pyramid, the largest of which is the pyramid of Pharaoh Khufu (about 2589-2566 BC) of the fourth dynasty in ancient Egypt. It is said that once Khufu instructed the chef to prepare a banquet for the guests, a chef accidentally knocked over a box of butter in charcoal ashes. He quickly took out the charcoal ash mixed with butter and threw it away. When he came back to wash his hands with water, he was surprised to find that his hands were particularly clean. When Pharaoh Khufu learned about it, he immediately ordered imitation, and the earliest soap of mankind came out. This is an ancient Egyptian legend about soap.

This legend may come from the narrative in the book Natural History written by Pliny the Elder (23-79), an ancient Roman writer and historian in the 1 th century. The bathing Romans boiled plant ash in water, then added animal fat into plant ash water, and then continuously added peat to stir until it was thick and mushy, so as to scrub the dirt on their bodies.

By 1 180, Bristol, a port city in southwest England, had become the European soap trade center at that time. According to the British historian John Stowe (1525- 1605), there were three kinds of soaps during the reign of Queen Elizabeth I (1533- 1603). The first is coarse soap made of whale oil. The second is sweet soap made of olive oil produced in Seville, a city in southwest Spain, and the third is spotted or gray soap made of butter. History of industrial chemistry. London: Heineman, 1957. . These soaps are all made in plant ash.

Plant ash contains potassium carbonate, and the soap produced by its chemical reaction with animal and vegetable fats is potassium soap, which is viscous semi-solid or liquid, usually yellow-green. It was not until the emergence of Lubran's alkali production method, especially after the successful preparation of sodium hydroxide by electrolytic brine, that a large number of solid washing soaps-sodium soaps used today appeared. Potassium soap is used as a detergent for cars and airplanes.

During the period of 18 13- 1823, French longevity chemist Chevreux (1786- 1889) published the saponification results of glycerol stearate and palmitoyl glyceride, the main chemical components in animal and vegetable fats, and pointed out that sodium stearate or palmitoyl acid was generated by saponification. It is pointed out that soap is a kind of fatty acid salt, which is insoluble in concentrated salt solution, while glycerol is very soluble in salt solution, so soap and glycerol can be separated by adding salt. So the production of soap became a chemical industry. In production practice, animal fat and caustic soda are boiled in a large pot for a period of time, then fine salt powder is poured in, and thick paste emerges from the pot, which is scraped into a mold and cooled into a bar of soap.

/kloc-around 0/870, sodium silicate was first added as a filler and then various spices were added when making soap in Britain. With the increasing demand for soap, more and more animal fat is converted into vegetable oil.

Working people in ancient China used natural products to wash clothes very early, and the earliest ones were plant ash's bath lotion and trona solution. In addition, the roots, leaves and fruits of many plants can be used for washing. Gleditsia sinensis is a common fruit, which contains saponin, which is a neutral polymer compound. It can form lasting foam in hard water and soft water, so that silk and wool fabrics have good luster and feel after washing, but saponin is toxic.

In the 5th century, Jia Sixie, an agricultural scientist in China, wrote The Book of Qi Yao Min, which said that pig pancreas could be decontaminated. This is because there are many digestive enzymes in animal pancreas, which can decompose fat, protein and starch, and have the function of removing dirt. By the end of the Qing Dynasty, washing products such as "osmanthus pancreas" and "rose pancreas" appeared in the market. This is a kind of "soap" created by China, which is made by mixing and grinding pig pancreas, sugar, trona, pig fat and spices, stirring and pressing them into balls or blocks. When European and American soaps were introduced into China, they were named "foreign pancreas". China/KLOC-The "foreign pancreas" appeared in the second half of the 9th century. From 65438 to the early 1960s, British and German businessmen came to China to set up factories to produce soap. The first soap enterprise run by China people was Tianjin Zhonghua Pancreas Company founded by Song Hengchun, which applied for registration in the 29th year of Guangxu reign of Qing Dynasty (1903).

Soap is a detergent, a surfactant and a substance that can reduce the surface tension of liquid. The surface tension of liquid is a force that liquid surface molecules are attracted by internal molecules, which makes the liquid tend to shrink. Water droplets in the air, dew on leaves and dew on grass are all spherical because of surface tension. Dropping a few drops of oil into a small bottle of water, even after covering the lid and shaking violently, the oil is still a small oil bead, which is also due to surface tension. But adding a small amount of soapy water to water containing small oil droplets is a different story. After oscillation, oil and water are no longer separated, but an emulsion similar to milk is formed.

The main chemical component of soap is sodium stearate (C 17H35COONa). It dissociates in water:

As a washing product, soap has served mankind for thousands of years and made great contributions. However, with the progress of human civilization and the needs of society, it is facing more and more challenges.

First of all, the production of soap needs oil, and each soap needs about 100 grams of oil. With the increase of population all over the world, the supply of edible oil is increasingly tight. With the development of industry, the contradiction between supply and demand has become increasingly prominent.

Secondly, when washing clothes with hard water, soap will combine with calcium ions and magnesium ions contained in hard water to generate water-insoluble sediment, which not only wastes soap, but also firmly absorbs in the gaps of fabric fibers, making clothes yellow and hard.

So chemists looked for a substitute for soap, and someone found Turkish red oil. 1834, krum, the owner of British printing and dyeing factory (1795- 1867) sulfonated olive oil with sulfuric acid. Its molecules also contain lipophilic and hydrophilic groups, which have wetting, emulsifying and dispersing effects. Besides dyeing, it is also used for tanning and papermaking, but the washing effect is not obvious.

During World War I, Germany was short of oil. 19 16 years, chemist Fritz Gunther made propane-based naphthalene sulfonic acid and sodium butyl alkyl naphthalene sulfonate, and Nekal A and NekalBX were put into the market as detergent commodities respectively. First of all, Clifton e melon. Detector-soap and synthetic detergent. Chemistry, proposed 65438. . These detergents belong to the short-chain alkyl aryl sulfonate type.

In the early 1930s, long-chain alkyl aryl sulfonates appeared in the American market, and the aryl groups were changed from naphthalene to benzene, that is, alkylbenzene sulfonates, in which both benzene and alkyl groups came from kerosene or light diesel oil. Their molecules also contain hydrophilic groups and lipophilic groups like soap, but unlike soap, their salts with calcium ions and magnesium ions in hard water are soluble in water.

The molecular structure can be represented by the following formula:

Starting from about 1965, all major detergent manufacturers changed their formulations from branched alkylbenzene sulfonates to linear alkylbenzene sulfonates.

Sodium carboxymethyl cellulose has been known in industry for many years. 1936 someone applied for a patent in France to use it as an additive for detergent. But this patent didn't play much role. It was not until World War II that Germany began to use sodium carboxymethyl cellulose as a supplement to detergents because of the shortage of soap. Later, synthetic detergent became a wartime substitute for soap, and detergent was used as an additive, so it was widely used in this industry. Sodium carboxymethyl cellulose is a white powder, which can be dissolved in water to form a viscous solution and can eliminate the redeposition of dirt in the washing process of detergent.

Another important additive of detergent is sodium tripolyphosphate, which can remove calcium ions and magnesium ions from water. However, in recent years, it has been found that it flows into rivers and lakes, which leads to the proliferation of algae, affects the survival of fish and causes water pollution. Therefore, all kinds of phosphorus-free washing powder have come out.

Additives include fluorescent whitening agents, which can absorb ultraviolet rays invisible to the naked eye and then turn them into white visible light, so the washed textiles are particularly white in the sun. Foaming agent can increase foam and absorb oil and dirt in water. Enzymes can decompose and destroy blood, milk stains and gravy at a certain temperature.

Sodium alkylbenzene sulfonate and soap belong to anionic surfactants because they dissociate into an anion with long-chain hydrophobic groups and short hydrophilic groups in water. They are the main categories of surfactants for washing, accounting for 65%~80% of the total output, with the largest dosage and the widest application.

Followed by cationic surfactant, which dissociates into a cation with long-chain hydrophobic groups and short hydrophilic groups in water, can be used for sterilization and disinfection, and can be used as fiber softener, leveler, mildew inhibitor, color fixing agent and antistatic agent in textile printing and dyeing industry.

Thirdly, there are many kinds of nonionic and zwitterionic surfactants. The output of synthetic detergent is increasing year by year, and it is gradually replacing soap.