Laundry detergent

 ( German Inventions ) 

German chemical companies developed an alkyl sulfate surfactant in 1917, in response to shortages of soap ingredients during the Allied Blockade of Germany during World War I. In the 1930s, commercially viable routes to were developed, and these new materials were converted to their Organosulfate, key ingredients in the commercially important German brand FEWA, produced by BASF, and Dreft, the U.S. brand produced by Procter & Gamble. Such detergents were mainly used in industry until after World War II. By then, new developments and the later conversion of aviation fuel plants to produce tetrapropylene, used in household detergents production, caused a fast growth of domestic use in the late 1940s.

• Water-soluble soils such as sugars, inorganic salts, urea, and perspiration.
• Solid particulate soils such as rust, metal oxides, soot (carbon black), carbonates, silicates, and humus.
• Hydrophobic soils such as animal fats, vegetable oils, sebum, mineral oil, and grease.
• Proteins such as blood, egg, milk, and keratin from skin. These require enzymes, heat or alkali to hydrolyze and denature them into smaller parts before they can be removed by the surfactants.
• Bleachable stains such as wine, coffee, tea, fruit juices, and vegetable stains. Bleaching is an oxidation reaction which turns the colored substance into a colorless one, which either stays on the fabric or may be easier to wash out.

Soils difficult to remove are pigments and dyes, , resins, tar, waxes, and denatured protein.

The earliest builders were sodium carbonate (washing soda) and sodium silicate (waterglass). In the 1930s (sodium phosphates) and (sodium hexametaphosphate) were introduced, continuing with the introduction of (Etidronic acid, ATMP, EDTMP). While these phosphorus-based agents are generally non-toxic they are now known to cause nutrient pollution, which can have serious environmental consequences. As such they have been banned in many countries, leading to the development of phosphorus-free agents, such as polycarboxylates (EDTA, NTA), (trisodium citrate), (sodium silicate), gluconic acid and polyacrylic acid; or ion exchange agents like .

Alkali builders may also enhance performance by changing the pH of the wash. Hydrophilic fibers like cotton will naturally have a negative surface charge in water, whereas synthetic fibers are comparatively neutral. The negative charge is further increased by the adsorption of anionic surfactants. With increasing pH, soil and fibers become more negatively charged, resulting in increased mutual repulsion. The optimum pH range for good detergency is 9–10.5. Alkalis may also enhance wash performance via the saponification of fats.

Builder and surfactant work synergistically to achieve soil removal, and the washing effect of the builder may exceed that of the surfactant. With hydrophilic fibers like cotton, wool, polyamide and polyacrylonitrile, sodium triphosphate removes soil more effectively than a surfactant alone. It is expected that when washing hydrophobic fibers like and , the effectiveness of the surfactant surpasses that of the builder, however this is not the case.

Enzymes are required to degrade stubborn stains composed of (e.g., milk, cocoa, blood, egg yolk, grass), (e.g., chocolate, fats, oils), starch (e.g., flour and potato stains), and cellulose (damaged cotton , vegetable and fruit stains). Each type of stain requires a different type of enzyme: (savinase) for proteins, for greases, α-amylases for carbohydrates, and for cellulose.