A Common Chemical——Activated Charcoal
7440-44-0, activated carbon
Technically , any form of carbon, not just charcoal, can be used to make activated carbon products, but charcoal is one of the most common sources for activated carbon. Activated charcoal, also called activated carbon(CAS:7440-44-0), is a form of charcoal which has been specially treated to create an especially high surface area. There are a wide range of uses for it, ranging from water filtration to the treatment of poisoning. It is often included in products like filters which can be bought in the store, and it is also possible to buy the substance alone in bulk.
How Does It Work?
Activated charcoal is able to trap these odor-causing chemicals because it adsorbs them instead of absorbing things, which means that certain materials will actually stick to the surface of the activate charcoal and form a film. The odor-causing molecules attach themselves to the huge surface area of the activated carbon and they are unable to escape. The chemical can trap and hold most organic impurities, making it ideal for use in filters. Activated charcoal filters only work as long as there is available surface area that can attract and hold impurities, and once these sites are all occupied, the filter must be replaced. They can be effectively washed, as the liquid can wash away impurities within the porous structure and render it usable. Only certain types of activated carbon filters can be washed effectively, however, and it's important to know the distinction before attempting the washing. A single gram of activated carbon has a surface area in excess of 1,000 square meters, meaning that the activated carbon filter can be used for a long time at moderate absorption rates. The pore size and the way the pores are distributed across the activated carbon itself can greatly affect the amount and type of filtration that can be achieved.
Used As Filters
Activated charcoal filters appear in a variety of places in the home. Home air filtration and built-in faucet water filtration units often employ activated carbon filters for cleaner smelling air and cleaner tasting water. Shoe inserts often use the chemical to kill foot and residual shoe odors.
They are used in labs and factories to purify everything from chemicals to food and drink. Companies harness the filtering power of activated carbon to clean large amounts of water and even distilled spirits.
The flow rate of material through the filter also has a significant effect on the amount of impurities absorbed by the filter. The slower that material moves through the filter, the more effectively it will be able to absorb the impurities passing through it. Of course, activated carbon does have medical uses as well, for much the same reason. In medicine, it is used to treat suspected cases of poisoning. If given in time, it will adsorb the poison before it reaches the intestinal tract, limiting the amount of poison absorbed by the body. The material is also used in gas mask filters and hospital air filters, to adsorb various substances in the air which could be harmful.