The Multi-Purpose Charcoal Filters

Gas masks are great: they help you get through the day should you find yourself in the middle of a toxic gas leak, a forest fire, or your friend's burrito aftermath. What's even more interesting about them is that the masks' filters are nearly the same substance as the material your friend must have grilled his burrito on – they're both charcoal.

Charcoal is used as filter for a wide variety of devices. Its forms also vary: it could appear as solid carbon, foam, powder or even cloth. The most common use of a charcoal filter is to relieve impurities. Using the handy-dandy gas mask as an example, the air you breath inside it must first pass a compartment containing the charcoal filters, eliminating toxic substances (like burrito odor, for example) that might have accompanied the oxygen you're about to inhale. Like gas masks, the filtering systems of air conditioners and exhaust fans also consist of charcoal filters.

But charcoal is not limited to filtering gaseous substances. Charcoal filters are also used for aquariums, coffee machines and even water treatment plants. Alcoholics will be surprised to know that most likely, the booze they're imbibing right now has undergone several layers of filtering. This procedure is called “leaching,” in which solid substances get strained. Don't worry, however, as the filtration doesn't affect the taste.

Technically, the charcoal used in these filters is called activated carbon. This charcoal has been heavily treated with oxygen so that its porosity will increase even more. Did you know that a gram of activated carbon can have as much as two kilometers’ worth of surface area? That's how much impurity activated carbon could hold.

The “filtering” action of charcoal filters is called “adsorb.” Adsorbing is bonding through chemical attraction. Because of the charcoal filter's huge surface area, it can adsorb very large amounts of impurities at any given time. Take note, however, that once all the surface area of the filter is bonded, it will stop adsorbing. At this time, you will have to replace your filter.

Now you know how your gas mask works, why air-conditioning smells good, or why water purifiers have charcoal in them. We all have to give our thanks to the humble charcoal filter.