Have you ever been in a situation in your house, bedroom,…perhaps , dorm room…and someone accidentally spills something on the carpet? I mean how many countless times does your “responsible” mother spill her red wine everywhere during one of her shows (Dancing with the Stars, Desperate Housewives, The Bachelor, etc.)? Or how about the number of times you return home and see that your loveable golden retriever puppy left you a “treat” on your new Kerastan carpet? Or even more likely (and surely more applicable to you fratstar college kids)—the number of occasions your college roommate had a bit too much to drink and, well, couldn’t find the trash can quick enough? Lucky you, there is a quick remedy to save your carpet: SpotShot Carpet Stain Remover.
Most cleaning agents work according to one of four mechanisms. These mechanisms employ either “like” solvents, surfactants, oxidizing agents, or “whiteners.” First, the stain remover may contain a certain solvent capable of dissolving the stain, which is based on the popular solubility aphorism “like dissolves like.” For instance, if your child accidentally wipes his greasy hands all over your carpet, the resulting grease stain will contain a bunch of hydrocarbons. In order to dissolve this grease stain, you would remove it by using an inorganic solvent containing hydrocarbons, since like dissolves like. On the other hand, you might have a stain as a result of, say, butter, which is an organic substance. As a result, you would want to remove the stain using an organic solvent, such as tetrachloroethylene. This technique, based on picking a solvent similar to your stain, is the same technique implored in dry cleaning.
A second approach—and the most frequently used in stain removers—employs surfactants, such as detergents, wetting agents, emulsifiers, foaming agents, and dispersants. Soap is a common surfactant, but stain removers often use sulfonates (pictured left), which are salts of sulfonic acid. Surfactants are usually organic, amphiphilic compounds. Amphiphilic molecules contain both hydrophobic groups and hydrophilic tails, so that they contain both a water-insoluble and a water-soluble component. Thus, a surfactant molecule contains a long, hydrophobic tail with a small, polar head. The hydrocarbon tail can surround (i.e. dissolve) the grease stain, and the polar ends dissolve in water. As a result, these surfactant molecules can interact with each other, forming a micelle around a “stain” molecule (pictured below). This micelle is water-soluble and gets washed away. In this process, which is called emulsification, stains are thus removed via the formation of micelles by surfactant molecules around inorganic (or organic) stain molecules.
A third mechanism stain removers might use involves “eating the stain.” By using oxidizing agents, such as chlorine bleach or peroxides, stain removers can break the bonds holding the long-chain stain molecules together. The products of this oxidation reaction are water-soluble and can be washed away more easily by the solvent. In food-related stains, biological and enzyme detergents work well since they release enzymes that act as catalysts to speed up the chemical digestion of the proteins and fats in these stains.
Lastly, the fourth approach (and certainly a “shortcut” or “last resort” for stain removers) essentially hides the stain from eyesight. They employ detergents like bleach that disrupt the bonds between chromophore molecules, which absorb light at specific wavelengths, re-emitting it as visible light to produce “color.” In this case, the optical properties of the stain molecule are changed and seem to be “colorless.” So with this technique, although we may say that the stain left from dog doo on your living room carpet has been “removed,” the dog doo is actually still there: it just is no longer visible. Comforting…it makes you think twice about lying down on that carpet of yours, huh?
In sharing these stain-removing properties with you, I hope you have had some sort of “common sense science” revelation. We often overlook simple everyday items and how they might function. However, it is important to realize that these seemingly simple items function scientifically—whether chemically, biologically, physiologically, or physically—and that we can benefit from understanding the scientific principles that they employ, no matter how basic or how intricate they may seem.