Welcome to Brainstuff from how Stuff works dot com where smart happens. This podcast is brought to you by Audible dot com, the Internet's leading provider of spoken word entertainment. Get a free audio book download of your choice when you sign up today. Log on to audible podcast dot com slash brain Stuff today for details. I am Marshall brain with today's question. What is activated charcoal and why
is it used in filters? Charcoal is carbon. Activated charcoal is charcoal that has been treated with oxygen to open up millions of tiny pores between the carbon atoms. These pores give the charcoal amazing surface area, maybe a thousand square meters or more per gram of charcoal. The word ads orb is important here. When a material adds orbs something, it attaches to it by chemical attraction. The huge surface
aery of activated charcoal gives it countless bonding sites. When certain chemicals pass next to the carbon surface, they attached to the surface and they get trapped. Activated charcoal is good at trapping other carbon based impurities organic chemicals in other words, as well as things like chlorine, many other chemicals are not attracted to carbon at all. Sodium nitrates,
things like that so they pass right through. This means that an activated charcoal filter will remove certain impurities while ignoring others. It also means that once all the bonding sites are filled and activated charcoal filter stops working. At that point, you have to replace the filter. Do you have any ideas or suggestions for this podcast? If so, please send me an email at podcast at how stuff works dot com. For more on this and thousands of other topics, go to how stuff works dot com