Detergent is one of the most common household items. Unless you’re a nudist, and favor living without clothes or don’t mind
walking around in dirty, solid clothes that smell awful, a detergent is a real need. But how does a detergent work, really? To understand how a detergent works, then you will also need to know how surfactants work.
Why surfactants? Detergents are made up of several components, surfactants being one of them. Detergents are different from soap, as soaps do not contain surfactants. There’s a reason why bathroom soap you use for washing yourself will not be able to fully clean a cloth in the same way a detergent does. The chemistry behind how surfactants work is also the chemistry behind how a detergent does its job, which is to clean your clothes.
Surfactants basically work through significantly lowering the surface tension of a liquid, and in the case of detergents, water. Water, by itself, cannot clean stains, especially organic stains, which have oil in them. Water’s surface tension does not allow the oil and the water to interact, thus the saying “water and oil do not mix.” With the said surface tension lowered through the addition of the detergent / surfactant into the mix, the water becomes, in a sense, “wetter”, because it spreads itself more an is much looser than it was in it’s normal state.
To understand how surfactants work, you also need to understand a process called adsorption (which is not a typo, and is different from absorption), where the atoms and molecules collect on top of the water. The whole process is catalysed by surfactants. The collected atoms and molecules manifest itself on the surface of the water as a film of sorts, which is visible to the naked eye – something you’ll notice in water mixed with detergent