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How is powdered activated carbon used?

How much do you know about powdered activated carbon?
How much do you know about powdered activated carbon?
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The use of activated carbon is pretty straightforward: it boils down to combining infinitesimal grains of carbon with contaminated things you want decontaminated -- water, air, metals or the human body.

The great thing about carbon (other than giving birth to diamonds) is that it naturally binds to organic toxins. So if you add some carbon to contaminated water, the icky particles will cling to it -- then you scoop it out, leaving clean, drinkable H2O behind. If you’ve ever had water from a Brita filter, you’ve benefited from activated carbon.

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So what is activated carbon? Carbon is "activated" by steaming it at temperatures up to 1800 degrees Fahrenheit, creating lots of tiny pores and pockets. The powdered form takes this a step further, grinding the carbon into granules that are less than a millimeter in size.

The vital term is surface area. On a brick of carbon, only the molecules on the outside are available to bind to toxins. But if it's full of nooks and crannies, many more molecules are exposed and can be put to good use. In powdered form, that number skyrockets: One gram of powdered activated carbon can have a surface area of 500 square meters.

Activated carbon is often used to treat water.
Activated carbon is often used to treat water.
Michael Blann/Thinkstock

One of the most common uses for activated carbon is treating water. It acts as a sort of buffer, removing harmful toxins from wastewater, groundwater and drinking water. It even improves taste and odor.

It cleans the air you breathe, too: PAC is often built into air purifiers to adsorb volatile chemicals. (A note on adsorb vs. absorb: the latter indicates that one substance fully mixes with another; adsorb refers to two substances that bind together on a superficial level.)

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Did you know that carbon binds to certain kinds of toxins?
Did you know that carbon binds to certain kinds of toxins?

Activated carbon comes into play in the emergency room as well. Carbon binds to toxins and prevents them from being absorbed into the stomach and intestines. So when someone overdoses on alcohol or drugs, doctors and paramedics can administer activated carbon and save a life.

Institutions like the Alliance for Collaborative Research in Alternative Fuel Technology are working to expand the uses of activated carbon. One idea is that it could be used to as a sort of sponge to store natural and hydrogen gases. Gas would be attracted by Van der Waals forces to the carbon, making for a low-pressure, low-temperature method of storage and transportation.

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