Modern detergent was born from a wartime shortage of soap fats
Soap has washed clothes since Sumerian times, around 2,500 BC. But when the First World War left Germany short of fats, chemists turned to coal tar for substitutes. Those early efforts cleaned poorly, yet they began a line of synthetic cleaners that pushed soap out of laundries across the developed world by the 1950s.
Every detergent relies on surfactants, molecules with a water-loving head and a long oil-loving tail. That split personality lowers water's surface tension and lets grease mix with water. The molecules cluster into tiny spheres called micelles, tails inward, which trap oil, protein and grime; they start forming at a threshold known as the critical micelle concentration. Most products add builders to soften water, enzymes to digest proteins, fats or starches, and dyes or scents. The name comes from the Latin detergere, to wipe off.
Synthetic surfactants have an edge in hard water. The workhorse alkylbenzene sulfonates bind calcium less readily than soap does, so they form less scum. Surfactants fall into four families by electric charge: anionic types are the most common, with an estimated 6 billion kilograms made each year for household markets, while cationic ones clean poorly, non-ionic ones foam little, and zwitterionic ones carry balanced charges.
The commercial story runs largely through Germany. In 1876 Henkel sold a sodium silicate product as a universal detergent, and in 1907 it added the bleach sodium perborate to create Persil, sparing people the chore of scrubbing laundry by hand. Sulfating fatty alcohol produced an effective detergent in 1928, and Henkel began selling such products in 1932. Procter and Gamble launched Dreft in the United States in 1933, but sales stayed sluggish until phosphate builders arrived in the early 1940s. Post-war petrochemicals then supplied cheap raw material.
Success brought problems. Phosphates fed nutrient pollution, and branched alkylbenzene sulfonates lingered in rivers because microbes struggle to break them down. Manufacturers moved to linear versions, phosphate substitutes such as zeolite A, and gentler sugar-based surfactants, along with tablets, gels and pods. Detergents also work far from the laundry: about 300 parts per million in fuel keeps carburettors and injectors clean, and purified laboratory grades pry membrane proteins such as ion channels out of cells for study.
Source: Detergent
